Foreword This report has been prepared by ESMAP consultant Mr. Carlos Madureira, from Electricidade de Portugal, during an ESMAP mission to Angola from January 23 to February 23, 1990. The mission consisted of Messrs Michel Del Buono, Mission Leader; Kurt F. Schenk, Power Specialist, Deputy Mission Leader; Ms. E. Battaglini, Economist; Messrs. J. Baptists, Power Engineer/Econornist; C. Alves da Cruz and C. Ferreira da Silva, Hydro Plant Specialists; C. Madureira, Power Systems Planner; P. Bemardin, Accounting, Organizational and Institutional Expert; L Rivera, Financial Analysis; G. Selleri, Hydro Plant Planning and Construction Expert; A. Corsini, Thermal Generation and Transmission Line Expert; G. Brambilla and M. Scarfi', Electric Distribution Experts; Ms. M. Kronen, Environmental Expert. The report analyses the Northern, Central and Southern Electric Power System of Angola. It provides least-cost power development plans including the impact of Capanda. of these three separate systems. It also evaluates the potential benefits from interco~ection The 1990 mission was followed by another ESMAP mission in early June 1991 which reviewed and revised many of the conclusions and recommendations of the 1990 mission in the light of the recent peace agreement of May 1991. The cooperation by the Government of Angola, particularly the Secretariat of Energy and Water (formerly the Ministry of Energy and Petroleum); the electric utilities ENE, SONEFE, EDEL and CELB (now incorporated within ENE); and GAMEK, in charge of the development of the River Kwanza, is gratefully acknowledged. Funding for this project has been provided by UNDP (United Nations Development Program) and SIDA (Swedish International Development Agency). The Blue Cover Report entitled: "Angola: Power Rehabilitation and Technical Assistance -Priorities for Investment and Technical Assistance in the Electric Power Sector", was published in October 1991. The p r e s e n t r e p o r t r e f e r s t o t h e p a r t i c i p a t i o n o f i t s a u t h o r i n the Mord Bank Mission t h a t v i s i t e d Angola f r o m JAN.25 to FEB. 2 4 , 1990; according t o the R e f e r e n c e Terms f r o m 90.01.19, the main task attributed to the author was that of the e s t a b l i s h m e n t o f t h e Least-Cost Expansion P l a n f o r t h e Northern E l e c t r i c G e n e r a t i n g System o f Angola. W i t h t h e purpose o f i d e n t i f y i n g t h e problems and coliecting t h e maximum i n f o r m a t i o n , c o n t a c t s w i t h t h e M i n i s t r y o f Energy and O i l (MEP) t h e e l e c t r i c i t y u t i l i t i e s ENE, SONEFE and EDEL, b e s i d e s GAMEK, were e s t a b l i s h e d , namely: MEP EngQ R U I T I T 0 ( G a b i n e t e T B c n i c o ) ENE EngQ QUELHAS MOTA ( D i r e c t o r - G e r a l ) EngQ JOAO SIMAO ( A r e a de Estudos e P r o j e c t o s ) Eng9 JOSE REIS ( A r e a de Estudos e P r o j e c t o s ) EngQ LUIS MOURAO ( A r e a de E x p l o r a ~ Z I oe M a n u t e n ~ Z o ) EngQ AMOR BELO MARTINS ( A r e a de E x p l o r a q 3 0 e M a n u t e n ~ B o ) EngQ VICTOR C O R R E I A ( A r e a de ExploraqZio e Manuten~Zio) EngQ HORACIO SANTOS (R.A.H.L.) EngS M A R I A CAROLINA SANTOS (R.A.H.M.) SONEFE EngP PAUL0 MATOS ( D i r e c t o r - G e r a l ) EngQ GUERREIRO COELHO ( D i r e c ~ B oT h c n i c a ) EngQ HELEN0 DUARTE ( A r e a de Estudos e P r o j e c t o s ) EngQ JOAO SANCHES ( A r e a de E x p l o r a ~ Z i oe Manutensgo) EngQ JOSE M A R I N H O ( A r e a de E x p l o r a ~ B oe Manutenqiio) EngP EDUARDO NELUMBA ( A r e a de E x p l o r a ~ i i oe Manuten~Bo) Dra COMINGAS FERREIRA ( D e p a r t . de F i n a n ~ a se P l a n i f i c a ~ Z i o ) EDEL EngQ S I LVA NET0 ( D i r e c t o r - G e r a l ) EngQ LUCAS DA SILVA ( A r e a de E x p l o r a ~ B oe Manutensgo) EngQ V I C T O R FONTES ( G a b i n e t e de P l a n i f i c a @ o ) GAMEK EngQ HENRIQUE GUERRA (Chefe do Departamento T h c n i c o ) The r e p o r t i s made up by t h r e e c h a p t e r s : - t h e f i r s t chapter shows an a p p r a i s a l of the present s i t u a t i o n o f t h e E l e c t r i c System i n Angola; - i n t h e second c h a p t e r , t h e Least-Cost Expansion P l a n o f the N o r t h e r n E l e c t r i c G e n e r a t i o n System o f Angola, w i t h i n t h e h o r i z o n o f year 2015, i s g i v e n , as w e l l as an a n a l y s i s on the i n t e r e s t i n the establishment o f the interconnection o f t h e N o r t h e r n E l e c t r i c System t o t h e C e n t r a l and Southern E l e c t r i c Systems. - i n t h e t h i r d c h a p t e r , t h e expansion p l a n s o f t h e C e n t r a l and Southern E l e c t r i c Systems a r e e s t a b l i s h e d , within the h o r i z o n of t h e y e a r 2005, a t t h e h y p o t h e s i s t h e y w i l l remain i s o l a t e d , l i k e t h e y a r e today. TABLE OF CONTENTS Pane s i a 1 .I - --------- STRUCTURE .................................................. 1.2- THE ELECTRIC GENERATING SYSTEM OF ANGOLA (EG.S.A.) 1.3- ................................................. THE NORTHERN ELECTRIC GENERATION SYSTEM (N.EG.S.) ................................................. THE SOUTHERN ELECTRIC GENERATING SYSTEM (S.EG.S.1 2 - LEAST-COST EXPANSION PLAN (L.C.E.P.) OF THE N.EG.S. 10 2.1- ----------------- B A S I S HYPOTHESIS 10 ............................. 2.2- ESTABLISHMENT OF THE L.C.E.P. 13 2.2.1- METHODOLOGY 2.2.2- ANALYSIS OF THE RESULTS 2.2.3- COST ESTIMATES AND INVESTMENT PLANS 2.2.4- LONG RUN MARGINAL COSTS (L.R.M.C.) 2.2.5- CONCLUSIONS AND RECOMMENDATIONS 2.3.1- IMPACT ON THE L.R.M.C. OF THE N.EG.S. 20 2.3.2- ECONOMICAL ANALYSIS 22 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS CHAPTER 1 - The E l e c t r i c System o f Angola i s composed, besides several i s o l a t e d systems, by t h e N o r t h e r n System, whose main potential i s found i n the r i v e r Kwanza, the Central System, including the r i v e r Catumbela b a s i n , and t h e S o u t h e r n System, i n c l u d i n g t h e r i v e r Cunene b a s i n . A t t h e b e g i n n i n g o f 1990 t h e E l e c t r i c System o f Angola i t was i n a s i t u a t i o n o f generalised rupture: - C o n c e r n i n g t h e h y d r o power s t a t i o n s . Mabubas (17.8 M W ) , at t h e N o r t h e r n System, and Lomaum ( 3 5 MW), a t t h e C e n t r a l System, were t o t a l l y u n a v a i l a b l e . . B i 6 p i o (14.4 MW), at the Central System, and M a t a l a ( 2 7 . 2 MW), a t t h e S o u t h e r n System, were i n precarious conditions. . additionally, a t the l a r g e s t power s t a t i o n o f Angola, Cambambe ( 4 x 45 MW), i t i s n e c e s s a r y t o c a r r y o u t t h e o v e r h a u l i n g and t h e r e p a i r o f t h r e e o f i t s f o u r u n i t s . - Concerning t h e thermal u n i t s . t h e gas t u r b i n e o f Bi6pio ( 2 2 . 8 MW) and t h r e e o f the f o u r d i e s e l u n i t s , w i t h t h e u n i t a r y c a p a c i t y o f 5 MW, of L o b i t o , a t t h e C e n t r a l System, were t o t a l l y u n a v a i l a b l e . . one o f t h e two d i e s e l u n i t s , w i t h unitary capacity o f 5 . 7 5 MW, of Namibe, a t t h e S o u t h e r n System, a l s o was unavai l a b l e . So, i n r e l a t i o n t o t h e i n s t a l l e d c a p a c i t y a r e o n l y a v a i l a b l e 73% a t t h e N o r t h e r n System, 24% a t t h e C e n t r a l System and 37% a t t h e S o u t h e r n System a s w e l l as a t t h e whole o f t h e i s o l a t e d systems; in a d d i t i o n o t h e r equipments such as s u b s t a t i o n s and t r a n s m i s s i o n l i n e s were u n a v a i l a b l e . I t i s recommended w i t h a b s o l u t e p r i o r i t y t o c a r r y o u t t h e restoring o f a l l t h e u n a v a i l a b l e g e n e r a t i n g c e n t r e s and o t h e r equipments above referred, being v i t a l t o r e c k o n upon a l l t h e u n i t s o f Cambambe a t t h e end o f 1992, i n o r d e r t o meet t h e demand o f e n e r g y and c a p z c i t y a t t h e N o r t h e r n System. CHAPTER 2 - The Least-Cost Expansion P l a n f o r t h e N o r t h e r n System o f Angola was e s t a b l i s h e d : - f o r t h e p e r i o d between 1993 and 2015; - f o r two s c e n a r i o s o f t h e demand e v o l u t i o n : a H i g h S c e n a r i o c o r r e s p o n d i n g t o t h e I n t e r m e d i a t e S c e n a r i o d e f i n e d by t h e W B Mission o f 1987 o n l y a d j u s t e d f r o m t h e a c t u a l value v e r i f i e d i n 1989 onwards; a Low S c e n a r i o d e f i n e d i n t h e scope o f t h e p r e s e n t m i s s i o n ; - based on t h e f a c t t h a t i t i s n o t p o s s i b l e t o r e a l i z e t h e h e i g h t e n i n g o f t h e Cambambe dam and t h e c o n s t r u c t i o n o f t h e second power s t a t i o n b e f o r e a b o u t t h e year 2010. So, i n view o f t h e advanced c o n d i t i o n o f t h e works a t t h e h y d r o p r o j e c t of Capanda t h i s was c o n s i d e r e d as t h e f i r s t c a n d i d a t e t o t h e system e x p a n s i o n , although i t as been contemplated a t six a l t e r n a t i v e s , r e s u l t i n g o f two demand e v o l u t i o n s c e n a r i o s and t h e following three situations: ALTERNATIVE I-Observance o f t h e c o n s t r u c t i o n s c h e d u l e as i t was (ALT.1) e s t a b l i s h e d by GAMEK, w i t h t h e c o n c l u s i o n o f t h e dam, w i t h 110 m e t e r s o f h e i g h t , t i l l t h e end o f 1992,but i n s t a l l i n g t h e f i r s t u n i t o n l y when necessary f o r t h e system, what happens a t 1996, f o r t h e H i g h S c e n a r i o (ALT.I.A), and a t 1998, for t h e Low Scenario (ALT.1.B). ALTERNATIVE 11- Corresponding t o t h e s c h e d u l e o f GAMEK, having (ALT.11) i n o p e r a t i o n t h e f i r s t u n i t a t t h e b e g i n n i n g o f 1993 and t h e second u n i t a t t h e m i d d l e o f 1993. ALTERNATIVE 111 - Construction o f a l o w e r dam, w i t h 91 m e t e r s o f (ALT.111) height, t i l l t h e end o f 1992, but i n s t a l l i n g the f i r s t u n i t o n l y as r e f e r r e d a t A l t e r n a t i v e I. By means o f t h e u t i l i z a t i o n o f t h e VALORAGUA model ( w h i c h e n a b l e s t o s i m u l a t e t h e o p t i m i z e d o p e r a t i o n o f a mixed h y d r o - t h e r m a l electric system u s i n g a t i m e - s e r i e s of t h e i n f l o w s t o t h e h y d r o power s t a t i o n s ) t h e f i r m g e n e r a t i o n s and c a p a c i t i e s o f Capanda f i t t e d w i t h one, t w o , t h r e e o r f o u r u n i t s ( w i t h t h e u n i t a r y c a p a c i t y o f 130 M W ) were e v a l u a t e d , b e i n g p o s s i b l e i n t h i s manner t o d e f i n e t h e commissioning d a t e s f o r t h o s e u n i t s . S i m i l a r l y , t h e o p p o r t u n i t y dates f o r t h e h e i g h t e n i n g o f t h e Capanda dam and f o r t h e commissioning o f t h e two u n i t s o f 130 MW each one t o be i n s t a l l e d in a first phase a t t h e second power s t a t i o n o f Cambambe, as w e l l as t h e o p p o r t u n i t y date f o r the heightening a t the Capanda dam a t ALTERNATIVE 111, were defined. Thus, several flows concerning the generations of Capanda and of the second power station of Cambambe were established, as well as the flows concerning the corresponding costs. It was used a constant prices system referred to the end of 1989, the discount rates of 10, 12 and 15% an'd a period of life of 50 years. Discounting those flows to the beginning of 1990, the levelized generating costs which are identified as the Long Run Marginal Costs from Capanda, from the second power station of Cambambe and from the set Capanda-Cambambe were computed. The results point out that the minimum levelized generating costs are found for the ALT.1 which is consequently considered the best option for the Expansion Plan for the Northern System; the commissioning dates for the four units of Capanda are from 1996 to 2009, at the High Scenario, and from 1998 to 2017, at the Low Scenario. So, the heightening of the Cambambe dam and the construction of its second power station results so far that its execution becomes very questionable. Thus, it is recommended the research of better alternatives by means of the achievement prefeasibility studies, with a satisfactory technical and budgetary characterization, concerning some hydro projects whose dimension seems to be more adjusted to the scale of the electric system of Angola, such as: Middle Kwanza River Basin - Zenzo I1 Queve River Basin - Caivole and Cachoeiras do Binga Longa River Basin - Quissula, Cassongo, Lungo and Murimbo Lastly, and using again the VALORAGUA model which allows the study of several systems interconnected by a simplified network, it was analized the interest in the establishment of the interconnection of the Northern Electric System to the Central and Southern Systems, by means of a transmission line at 220 kV from Cambambe to Lubango, passing through Gabela and Bi6pio with a length 570 km. The transit of the surplus of power existing until about 2025 at Northern System to the Central and Southern System enables important savings of fuel consumption besides to postpone large investments at the Central and Southern System, so that the interconnection results justifiable under a strictly economic viewpoint. However it is recommended the analysis of the problem under a technical point of view, specially concerning its contribution for the reliability of the Northern, Central and Southern Systems operation. CHAPTER 3 - The Expansion P l a n s o f t h e C e n t r a l and Southern E l e c t r i c Systems a t t h e h y p o t h e s i s o f r e m a i n i n g i s o l a t e d were e s t a b l i s h e d : - f o r t h e H i g h S c e n a r i o o f t h e demand e v o l u t i o n , c o n s i d e r e d a t t h e p r e c e d i n g c h a p t e r , f o r t h e a n a l y s i s on t h e i n t e r e s t o f t h e i n t e r c o n n e c t i o n , i n o r d e r t o a l l o w a v a l i d comparison o f t h e results; - f o r t h e p e r i o d between 1995 and 2005, b e i n g assumed t h a t a t 1995 a1 1 t h e equipments t o t a l on p a r t i a l l y u n a v a i l a b l e a t t h e p r e s e n t s h o u l d be r e h a b i l i t a t e d . The r e s u l t s p o i n t o u t t o t h e n e c e s s i t y t o i n s t a l l two new t u r b i n e s , e v e n t u a l l y b u r n i n g n a t u r a l gas, a t t h e a r e a o f Benguela - Lobito, w i t h t h e c a p a c i t i e s of 25 MW, a t 1997, and 30 MW, a t 1998, i n o r d e r t o t h e u t i l i z a t i o n o f t h e gas t u r b i n e s , a t t h e C e n t r a l System, w i l l remain between 1200 and 1600 h o u r s , w i t h i n t h e s t u d y p e r i o d . I n addition t o this, and c o n c e r n i n g t h e C e n t r a l System h y d r o component, t h e power s t a t i o n o f Lomaum must be u p r a t e d w i t h t h e two pre-existing u n i t s with the capacity o f 10 MW each one, after complete r e h a b i l i t a t i o n , from 1996 onwards, and t h e Cacombo dam must be f i n i s h e d a t 1999, although t h e r e s p e c t i v e power station ( 2 x 12 M W ) o n l y be necessary a t 2003; a t t h e Southern System w i l l be needed t o i n s t a l l a power s t a t i o n a t t h e Gove dam ( 2 x 1 5 M W ) f r o m 1998 onwards and an a d d i t i o n a l u n i t o f 15 MW a t 2002. For a c o n s t a n t p r i c e s system r e f e r r e d t o t h e end o f 1939, t h i s program c o m p a r a t i v e l y t o t h e h y p o t h e s i s w i t h t h e i n t e r c o n n e c t i o n s i g n i f i e s an i n c r e a s e o f i n v e s t m e n t s , d i s c o u n t e d t o t h e b e g i n n i n g o f 1995, r e a c h i n g amounts between 152 and 170 M. USD, a t t h e C e n t r a l System, and between 33 and 40 M. USD a t t h e Southern System, which p o i n t s o u t t h e i n t e r e s t on t h e c o n s t r u c t i o n o f t h e t r a n s m i s s i o n l i n e f o r t h e i n t e r c o n n e c t i o n o f t h e N o r t h e r n System t o t h e C e n t r a l and Southern Systems. However, i f t h a t i n t e r c o n n e c t i o n w i l l n o t be t e c h n i c a l l y a d v i s a b l e , i t i s recommended t o s t u d y t h e i n t e r c o n n e c t i o n o f t h e C e n t r a l and t h e Southern Systems, t h r o u g h a t r a n s m i s s i o n l i n e Gove - Huambo due t o t h e s h o r t d i s t a n c e between t h e s e two p l a c e s ; i n such case, and as consequence o f t h e l o w e r p o t e n t i a l o f t h e r i v e r Catumbela r e l a t i v e l y t o t h e r i v e r Cunene, i t i s suggested t h e s t u d y o f t h e i n t e g r a t i o n o f t h e h y d r o p r o j e c t o f Jamba I a Mina (130 MW; 580 GWh), on t h e r i v e r Cunene, w h i c h p r o b a b l y c o u l d a v o i d o r d i f f e r f o r many years t h e c o n s t r u c t i o n o f t h e Cacombo dam, on t h e r i v e r Catumbela. 1 - PRESENT SITUATION OF THE POWER SYSTEM I N ANGOLA 1-1- --------- STRUCTLIRE B a s i c a l l y t h e s t r u c t u r e o f Angola's Power System i s composed by t h e f o l l o w i n g companies: - ENE (Empresa Nacional de E l e c t r i c i d a d e ) I t i s a S t a t e e n t e r p r i s e , e s t a b l i s h e d i n 1980 w i t h t h e intention of becoming t h e o n l y n a t i o n a l power u t i l i t y i n charge o f g e n e r a t i o n , t r a n s m i s s i o n and d i s t r i b u t i o n a t medium v o l t a g e a l l over t h e c o u n t r y . Nowadays, however, th.is enterprise just operates t h e C e n t r a l and t h e Southern Systems, and some i s o l a t e d systems i n s e v e r a l p r o v i n c e s , besides being r e s p o n s i b l e f o r t h e d i s t r i b u t i o n a t low v o l t a g e a l l over t h e c o u n t r y , w i t h the e x c e p t i o n o f t h e areas of Luanda and of s e v e r a l l o c a l municipal bodies (Comissariados) who a r e r e s p o n s i b l e f o r t h e d i s t r i b u t i o n a t low v o l t a g e and may a l s o be owners o f small d i e s e l u n i t s ; - SONEFE (Sociedade Nacional de Estudos e Financiamento de Empreendimentos U l t r a m a r i n o s ) I t operates t h e N o r t h e r n System, t h e l a r g e s t i n t h e c o u n t r y , i n c l u d i n g t h e area of Luanda and t h e p r o v i n c e s o f Bengo, N o r t h and South Kwanza and Malange, being i n charge o f g e n e r a t i o n , t r a n s m i s s i o n and t h e d i r e c t supply o f about 300 customers a t h i g h ( 6 0 k V ) and medium v o l t a g e . - EDEL (Empresa de E l e c t r i c i d a d e de Luanda) It i s i n charge of d i s t r i b u t i o n a t low v o l t a g e i n t h e area of Luanda. - CELB (Companhia E l e c t r i c a do L o b i t o e Benguela) I t i s i n charge of d i s t r i b u t i o n i n t h e p r o v i n c e o f Benguela. 1.2- .................................................. THE ELECTRIC GENERATING SYSTEM OF ANGOLA (EG.S.A.) A t the beginning o f 1990 t h e EG.S.A. was b a s i c a l l y composed, besides s e v e r a l i s o l a t e d systems, by t h r e e independent systems who s u p p l y t h e p r i n c i p a l c e n t e r s o f consumption: - t h e N o r t h e r n System - who s u p p l i e s t h e a r e a o f Luanda and i s o p e r a t e d by SONEFE. I t uses t h e h y d r o p o t e n t i a l o f t h e r i v e r Kwanza, where t h e power s t a t i o n o f Cambambe (180 M W ) is l o c a t e d , and o f t h e r i v e r Dande, where t h e power s t a t i o n of Mabubas ( 1 7 . 8 M W ) i s l o c a t e d , and two gas t u r b i n e s i n Luanda (56.8 MW), t o t a l i z i n g an i n s t a l l e d c a p a c i t y o f 254.6 MW ( T a b l e 1 f r o m ANNEX 1, pag. 1 ) ; - t h e C e n t r a l System - who s u p p l i e s t h e areas o f Benguela, L o b i t o and Huambo and i s o p e r a t e d by ENE. I t uses t h e h y d r o p o t e n t i a l o f t h e r i v e r Catumbela, where t h e power s t a t i o n s o f Lomaum (35 M W) and B i d p i o (14.4 M W ) a r e l o c a t e d , and t h e thermal u n i t s a t B i 6 p i 0 , one gas t u r b i n e (22.8 M W ) and two d i e s e l u n i t s ( 3 MW), a t Lobito, four d i e s e l u n i t s (20 M W ) i n s t a l l e d i n a railway carriage, and a t Huambo, one gas turbine (10 M W ) and s i x d i e s e l u n i t s ( 4 . 9 MW), t o t a l i z i n g an i n s t a l l e d c a p a c i t y o f 110.1 MW ( T a b l e 1 from ANNEX 1, pag. 1 ) ; t h e Southern System - who s u p p l i e s t h e a r e a s o f Lubango and Namibe and i s o p e r a t e d by ENE. I t uses t h e h y d r o p o t e n t i a l o f t h e r i v e r Cunene, where t h e r e g u l a t i n g r e s e r v o i r o f Gove and t h e power s t a t i o n o f M a t a l a (27.2 M W) are located, and i I the diesel u n i t s a t Lubango ( 3 . 6 MW), Namibe (11.5 MW), i Tombwe ( 1 . 6 MW), Jamba (5.7 M W ) and Saco (2.9 MW), I ! t o t a l i z i n g an i n s t a l l e d c a p a c i t y o f 52.5 MW ( T a b l e 1 f r o m ANNEX 1 , pag. 1 ) ; m The main i s o l a t e d systems a r e t h o s e o f Cabinda, Uige and B i e and i n t h e province o f Lunda-Norte t h e system b e l o n g i n g t o t h e m i n i n g company ENDIAMA (Empresa N a c i o n a l de Diamantes de Angola) and was m a i n l y used t o support diamond m i n i n g a c t i v i t i e s ( T a b l e 1 f r o m ANNEX 1 , pag 2 ) . . On t h e whole t h e E G . S . A . i s i n a s i t u a t i o n can be c o n s i d e r e d o f ., 7 generalized rupture, r e s u l t i n g n o t o n l y because none hydro power s t a t i o n was b u i l t a f t e r 1974 b u t m a i n l y due t o a l o n g s e r i e s o f sabotage a c t i o n s o v e r a l m o s t a l l hydro p l a n t s , w i t h exception o f Cambambe; i n t h i s case, however, t h e sabotage has f a l l i n g upon t h e t r a n s m i s s i o n l i n e Cambambe - Luanda, l e a d i n g t o severe p e r i o d s o f i n t e r r u p t i o n o f t h e e l e c t r i c i t y supply t o t h e c a p i t a l , f o r c i n g t h e i n t e n s i v e u t i l i s a t i o n o f t h e gas t u r b i n e s o f Luanda and consequently i t s i n e v i t a b l e premature e r o s i o n . Others sabotage a c t i o n s , f a l l i n g upon e i t h e r on s u b s t a t i o n s o r on - t r a n s m i s s i o n l i n e s , have added t o t h e worsening o f t h e s i t u a t i o n o f t h e Angola's E l e c t r i c System. From 1980 onwards, an e f f o r t was made i n o r d e r t o overcome t h i s s i t u a t i o n with the installation of two gas t u r b i n e s i n Luanda, in 1980 and 1985, one i n Huambo, i n 1981, and s e v e r a l d i e s e l u n i t s in L o b i t o and o t h e r i m p o r t a n t c e n t e r s . However, due t o t h e d e f i c i e n t maintenance, l a c k o f t e c h n i c a l a s s i s t a n c e and e x t r a spare p a r t s and the i r r e g u l a r i t y o f f u e l supplies, such d e c i s i o n s d i d n o t succeed i n s o l v i n g t h e problem. The gas t u r b i n e o f Huarnbo r e s t e d u n a v a i l a b l e in February 1985, t h a t o f B i 6 p i o i n 1988 and t h r e e d i e s e l u n i t s o f L o b i t o i n 1989. So, i n s p i t e o f t h e r e s t o r i n g a t o p e r a t i o n o f t h e gas t u r b i n e o f Huambo, i n t h e C e n t r a l System o n l y 27 MW, o f t h e 110 MW installed, a r e a v a i l a b l e , w h i l e i n t h e Southern System o n l y 19 MW, o f t h e 5 3 MW i n s t a l l e d , are available. O f the t o t a l i n s t a l l e d c a p a c i t y o f about 462 MW, i n t h e power s t a t i o n s o f ENE and SONEFE, o f which: - 287 MW i n hydro u n i t s ; - 102 MW i n gas t u r b i n e s ; - 73 MW i n d i e s e l u n i t s , o n l y were a v a i l a b l e about 248 MW, i n t h e b e g i n n i n g o f 1990, t h a t i s t o say, 54% o f t h e t o t a l , as t h e f o l l o w i n g t a b l e shows: HYDRO THERMAL TOTAL PEACK AT SYSTEM 1989 Instal. Avai 1. Instal. Avai 1. Instal. Avai 1. (a) NORTHERN 197.8 135.0 56.8 50.0 254.6 185.0 111 CENTRAL 49.4 10.8 60.7 15.8 110.1 26.6 15 SOUTHERN 27.2 13.6 25.3 5.7 52.5 19.3 10 ISOLATED 12.9 1.1 31.7 15.6 44.6 16.7 N.A. TOTAL 287.3 160.5 174.5 87.1 461.8 247.6 (a) Related t o generation; reflects d i s t i n c t levels o f suppressed demand. The suppressed demand I s estimated at about 12% i n the Northern System, 30% i n the Central System and 25% I n the Southern System. Source: SONEFE, ENE and Table 1 from ANNEX 1. H y d r o e l e c t r i c i t y has always been t h e main source o f s u p p l y , remaining i t s c o n t r i b u t i o n between 80-98% o f t h e t o t a l g e n e r a t i o n . In 1989, i n s p i t e o f t h e hydro u n a v a i l a b i l i t i e s , t o t a l a t t h e s t a t i o n of Lomaum and p a r t i a l a t t h e s t a t i o n o f Mabubas, t h a t c o n t r i b u t i o n was o f 89.5% (755 G W h o f hydro g e n e r a t i o n t o 884 G W h o f t.he t o t a l ) , b e l o n g i n g t o t h e s t a t i o n o f Cambambe t h e l a r g e s t p o r t i o n , 662 GWh, which means 87.7% o f a l l hydro g e n e r a t i o n and 78.4% o f the t o t a l generation (Table 2 from ANNEX 1 , pag. 3 ) . Luanda, the largest center o f consumption, belongs t o t h e N o r t h e r n System which, h a v i n g generated 695 G W h i n 1989, was t h e r e s p o n s i b l e f o r 82.4% o f t h e t o t a l g e n e r a t i o n ( T a b l e 3 from ANNEX 1, pag. 4 ) . 1.3- ................................................. THE NORTHERN ELECTRIC GENERATION SYSTEM (N.EG.S.) The N.EG.S. i s operated by SONEFE and is composed by the f o l l o w i n g generating centres: HYDROELECTRIC POWER PLANTS . CAMBAMBE, on t h e r j v e r Kwanza, whose3dam c o n t r o l s a b a s i n w i t h an c area o f 115,500 km , b e i n g o f 728 m / s t h e average f l o w o f t h e r i v e r on t h e s i t e o f t h e dam, i n t h e p e r i o d o f 20 yejars 1953/1972, i n which t h e minimum f l o w on t h e r i v e r was 130 m / s , v e r i f i e d i n October. T h i s power s t a t i o n , t h e l a r g e s t o f Angola, has an i n s t a l l e d c a p a c i t y o f 180 MW, f i t t e d w i t h f o u r u n i t s , wAth a nominal c a p a c i t y o f 45 MW and a t u r b i n i n g r a t e d f l o w o f 65 m / s each one. I t i s a r u n - o f - r i v e r t y p e power s t a t i o n , w i t h a d a i l y r e g u l a t i n g c a p a b i l i t y . The f i r m c a p a c i t y a t 100% o f t h e t i m e is 90 MW, r e s u l t i n g t h e n a f i r m energy o f 790 GWh; however, a t peak hours, t h e f i r m c a p a c i t y can reach 135 MW. Since t h e i n i t i a l p r o j e c t , and when t h e l e v e l o f t h e consumption would be j u s t i f i a b l e a h e i g h t e n i n g o f 20 meters o f t h e dam was f o r e s e e n , i n o r d e r t o i n c r e a s e t h e i n s t a l l e d c a p a c i t y t o 4x65=260 MW, s i m u l t a n e o u s l y w i t h t h e c o n s t r u c t i o n o f t h e i n l e t works o f a second power s t a t i o n t o be b u i l t l a t e r , f i t t e d with four units w i t h a nominal c a p a c i t y o f 110 MW each one. ~ e a n w h i ' l e , w i t h t h e c o n s t r u c t i o n o f t h e h y d r o e l e c t r i c power p l a n t o f Capanda, t h e above mentioned h e i g h t e n i n g o f t h e dam and t h e construction o f a second power s t a t i o n i n Cambambe w i l l be postponed f o r many years, assuming t h e p o s s i b i l i t y o f f i n d i n g a better alternative. Concerning t h e p r e s e n t c o n d i t i o n o f t h e g e n e r a t i n g u n i t s ( u n i t s 1 and 2 i n s t a l l e d i n 1963 and u n i t s 3 and 4 i n s t a l l e d i n 1973), a l l of them need an u r g e n t o v e r h a u l i n g and r e p a i r i n o r d e r t o be a t p e r f e c t o p e r a t i o n c o n d i t i o n s u n t i l t h e end o f 1992; t h e t o t a l r e h a b i l i t a t i o n , i n c l u d i n g g e n e r a t i n g u n i t s , power s t a t i o n and s u b s t a t i o n , i s e s t i m a t e d a t 9.38 m i l l i o n s o f USD. A f t e r t h e r e p a i r o f a l l u n i t s , t h e f i r m energy w i l l be 1080 GWh, more 100 G W h r e s u l t i n g from t h e r e g u l a t i o n induced by t h e r e s e r v o i r o f Capanda s i n c e t h e b e g i n n i n g o f 1993, and t h e f i r m c a p a c i t y a t 100% of t h e t i m e w i l l be 135 MW. The power s t a t i o n generated 662 G Wh i n 1989, which means 87.7% o f a l l h y d r o g e n e r a t i o n and 78.4% o f total generation i n the country. . MABUBAS, on t h e r j v e r Dande, whose c Jam c o n t r o l s a b a s i n w i t h an km , b e i n g o f T a r e a o f 7,490 30.5 m / s t h e average f l o w o f t h e r i v e r on t h e s i t e o f t h e dam. The power s t a t i o n , l o c a t e d 54 km a t n o r t h e a s t o f Luanda, was t h e f i r s t h y d r o e l e c t r i c power s t a t i o n b u i l t t o s u p p l y e l e c t r i c i t y t o Luanda and i t i s f i t t e d w i t h f o u r u n i t s , two i n s t a l l e d i n 1953 and t h e o t h e r two i n 1959, b e i n g t h e t o t a l i n s t a l l e d c a p a c i t y 2x3.0+2x5.9=17.8 MW. The power s t a t i o n i s o u t o f s e r v i c e s i n c e 1986 and a l l the h y d r o e l e c t r i c scheme needs a deep r e h a b i l i t a t i o n because, due t o t h e f a c t o f b e i n g embarrassed t h e g a t e s o f t h e s p i l l w a y and t h e bottom d i s c h a r g e , d u r i n g f l o o d p e r i o d s t h e water a l r e a d y passed o v e r t h e dam and a l s o was l a t e r a l l y s p i l l e d f r o m t h e channel of d e v i a t i o n t o t h e power s t a t i o n , severally deteriorating i t s foundation. I n t h e second quarter o f 1989 the power s t a t i o n generated 1.3 Gwh. THERMAL POWER STATION OF LUANDA W i t h an i n s t a l l e d c a p a c i t y o f 56.8 MW, i t i s f i t t e d w i t h two gas t u r b i n e s b u r n i n g J e t B f u e l , t h e f i r s t h a v i n g been i n s t a l l e d i n 1980 C and t h e second i n 1985, w i t h r e s p e c t i v e l y 25.6 and 31.2 MW o f nominal . . c a p a c i t y . A t t h e p r e s e n t c o n d i t i o n t h e v a l u e s o f 20 and 30 MW, r e s p e c t i v e l y , must be c o n s i d e r e d as f i r m c a p a c i t y . The g e n e r a t i o n o f t h e power s t a t i o n i n 1989 was 32.1 GWh. On t h e whole, t h e N.EG.S. generated 695 G Wh I n 1989, t h a t i s , 82.4% o f t h e t o t a l e l e c t r i c i t y g e n e r a t i o n o f Angola ( T a b l e 3 from ANNEX 1, page 4 ) , h a v i n g t h e maximum peak r e l a t e d t o t h e g e n e r a t i o n reached 11 1 MW. i 1.4- ................................................ THE CENTRAL ELECTRIC GENERATING SYSTEM (C.EG.S.) The C.EG.S. i s operated by ENE, i n t o which a f t e r t h e independence was i n c o r p o r a t e d HEAD ( H i d r o E l e c t r i c a do A l t o Catumbela, who was in charge o f g e n e r a t i o n and t r a n s m i s s i o n ) , b e i n g CELB t h e r e s p o n s i b l e f o r t h e d i s t r i b u t i o n i n t h e p r o v i n c e o f Benguela. The system s u p p l i e s t h e two most i m p o r t a n t r e g i o n s o f Angola a f t e r Luanda, concerning p o p u l a t i o n and i n d u s t r i a l development, w i t h the transmission lines r u n n i n g a p p r o x i m a t e l y p a r a l l e l t o t h e r a i l w a y of Benguela, and i t i s composed by t h e f o l l o w i n g g e n e r a t i n g c e n t r e s : HYDROELECTRIC PLANTS Both l o c a t e d on t h e r i v e r Catumbela a r e t h e f o l l o w i n g : . LOMAUM, whose dam c o n t r o l s a b a s i n w i t h an a r e a o f 8,296 km2, b e i n g 5he average f l o w o f t h e r i v e r on t h e s i t e o f t h e dam o f 86.3 m / s , i n t h e p e r i o d of 20 yeass 1953/1972, and t h e dryness f l o w w i t h 95% o f p r o b a b i l i t y o f 8m / s . The power s t a t i o n has an i n s t a l l e d capacity o f 35 MW, being f i t t e d w i t h two u n i t s , i n s t a l l e d i n 1964, w i t h a nominal c a p a c i t y o f 10 MW each one, and one u n i t , i n s t a l l e d i n 1972, w i t h a nominal c a p a c i t y o f 15 MW. The power s t a t i o n , o f t h e r u n - o f - r i v e r t y p e and o n l y w i t h a d a i l y regulating capability, i s o u t of o p e r a t i o n s i n c e 1983, period wherein was t a r g e t o f sabotage ( a s w e l l as t h e s u b s t a t i o n o f A l t o Catumbela), t h e i r penstocks h a v i n g been d e s t r o y e d which caused t h e f l o o d o f t h e power s t a t i o n and t h e d e s t r u c t i o n o f t h e c o n t r o l and p r o t e c t i o n systems. Before t h e r e f i t t i n g o f t h e t h r e e u n i t s a l r e a d y i n s t a l l e d i n t h e power s t a t i o n , i t i s foreseen with p r i o r i t y the i n s t a l l a t i o n o f two new u n i t s w i t h a nominal c a p a c i t y o f 15 MW each one, i n o r d e r t o be ready t o s t a r t o p e r a t i n g u n t i l t h e end o f 1992; t h e t o t a l r e h a b i l i t a t i o n o f t h e penstocks and t h e power s t a t i o n is e s t i m a t e d a t 62.3 m i l l i o n s o f USD, b e i n g t h e c o s t o f t h e new g e n e r a t i n g u n i t s e s t i m a t e d a t 5.3 m i l l i o n s o f DM. The r e s t o r i n g o f t h e t h r e e former u n i t s r e q u i r i n g r e p a i r w i l l be made l a t t e r i n a p r o p e r t i m e . r . BIOPIO, downstreay o f Lomaum, whose dam c o n t r o l s a b a s i n w i t h an area o f 15,550 km , b e i n g thegaverage f l o w o f t h e r i v e r on t h e s i t e o f t h e dam o f 117.3 m /s, i n the period o f 20 years 195341972, and t h e dryness f l o w w i t h 95% o f p r o b a b i l i t y o f 20 m /s. The power s t a t i o n has an i n s t a l l e d c a p a c i t y o f 14.4 MW , being f i t t e d w i t h f o u r u n i t s , i n s t a l l e d i n 1957, w i t h a nominal c a p a c i t y o f 3.6 MW each one. The power s t a t i o n , of the r u n - o f - r i v e r t y p e and o n l y w i t h a d a i l y r e g u l a t i n g c a p a b i l i t y , has nowadays o n l y t h r e e u n i t s i n o p e r a t i o n , h a v i n g generated 42 Gwh i n 1989 , t h a t i s , 51% o f t h e t o t a l g e n e r a t i n g o f C.EG.S. (83 GWh, i n c l u d i n g t h e power s t a t i o n s o f t h e p r o v i n c e s o f B i b and Moxico: Table 3 from ANNEX 1, pag.4). I n view o f t h e a n t i q u i t y of t h e f o u r u n i t s , more t h a n t h i r t y years, and t h e i r p r e s e n t c o n d i t i o n , t h e i r replacement by f o u r new u n i t s w i t h t h e same nominal c a p a c i t y of those i s f o r e s e e n as v e r y l i k e l y , as w e l l as t h e t o t a l r e h a b i l i t a t i o n o f t h e power s t a t i o n , what i s e s s e n t i a l t o assure u n t i l t h e end o f 1994, being i t s c o s t e s t i m a t e d a t 13.65 m i l l i o n s of USD. THERMAL POWER STATIONS . BICJPIO, where, i n 1974, was i n s t a l l e d a t u r b i n e b u r n i n g g a s o i l , w i t h a c a p a c i t y o f 22.8 MW and, i n 1982, two d i e s e l u n i t s w i t h a nominal c a p a c i t y o f 1.5 MW each one. A t t h i s moment a l l these u n i t s are out o f operation. . HUAMBO, where, i n 1981, was i n s t a l l e d a t u r b i n e b u r n i n g g a s o i l , w i t h a nominal c a p a c i t y of 13.5 MW t h a t , however, due t o t h e a l t i t u d e where i t i s l o c a t e d (1800 m), has an o u t p u t o f o n l y 10 MW. I t r e s t e d o u t o f o p e r a t i o n i n 1985, h a v i n g been r e s t o r e d r e c e n t l y . There a r e s t i l l f o u r d i e s e l u n i t s o f 0.8 MW each one, i n s t a l l e d i n 1953, and two new u n i t s , i n s t a l l e d i n 1986, w i t h a nominal c a p a c i t y of 0.85 MW, each one. P r e s e n t l y , o n l y one o f t h e u n i t s o f 0.8 MW i s a v a i l a b l e . . LOBITO, where, i n 1986, were ' i n s t a l l e d f o u r d i e s e l u n i t s o f 5 MW each one; however a t t h i s moment o n l y one o f t h e u n i t s is a v a i 1a b l e . As r e s u l t o f t h e u n a v a i l a b i l i t i e s o f t h e gas t u r b i n e o f B i 6 p i o and o f t h e t h r e e d i e s e l u n i t s o f L o b i t o , t h e g e n e r a t i o n o f C.EG.S., who had reached 108.5 G Wh i n 1987 ( i n c l u d i n g 5.0 G W h of t h e power s t a t i o n o f t h e p r o v i n c e of B i 6 and 0.5 G Wh o f Moxico) f e l l down t o T- 104.1 G W h i n 1988 and 83.0 G Wh i n 1989, meaning now 'only 9.8% o f t h e . ., t o t a l g e n e r a t i o n o f Angola; i n 1989 t h e peak o f t h e system, r e l a t e d t o g e n e r a t i o n , was around 15 MW, due t o t h e p r e s e n t s i t u a t i o n o f suppressed demand e s t i m a t e d a t 30%. The S.EG.S. i s operated by ENE and i s composed by t h e following generating centers: HYDROELECTRIC POWER PLANTS HATALA, on t h e r i 2 e r Cunene, whose dam c o n t r o l s a b a s i n w i t h an area o f 28,037 km , b e i n g t h e 2verage f l o w o f t h e r i v e r on t h e s i t e o f t h e dam o f 147.2 m / s i n t h e p e r i o d o f 20 years 1953/1972. The power s t a t i o n has as an i n s t a l l e d c a p a c i t y o f 27.2 MW s i n c e 1959, b e i n g f i t t e d w i t h two u n i t s w i t h a nominal c a p a c i t y o f 13.6 MW each one, b u t s i n c e 1984 i t works w i t h one u n i t out o f operation. The power s t a t i o n s u f f e r e d s e r i o u s l y d u r i n g s e v e r a l f i r e s and, i n consequence, the generators, the c o n t r o l - r o o m and t h e power c a b l e s a r e damaged. So, i t needs an u r g e n t r e h a b i l i t a t i o n f o r which a program a l r e a d y e x i s t s , going on a t t h i s moment t h e i n s t a l l a t i o n of a new u n i t w i t h t h e same nominal c a p a c i t y o f t h e o l d e r ones, and t h e n t h e r e p a i r o f t h e two o l d e r u n i t s . The power s t a t i o n i s t h e most i m p o r t a n t power p l a n t o f t h e S.EG.S., having generated, i n 1989, 43.2 GWh, that i s , 88.3% o f t h e t o t a l g e n e r a t i o n of t h i s system ( T a b l e 3 from ANNEXE 1, pag. 4 ) . Upstream of M a t a l a i s l o c a t e d t h e Gove dam, o f the e a r t h - f i l l t y p e , a l s o on t h e r i v e r Cunene, b e l o n g i n g t o t h e M i n i s t r y qf Construction, c o n t r o l l i n g . a b a s i n w i t h an a r e a o f 4,811 km , b e i n g g t h e average flow o f the r i v e r on t h e s i t e o f t h e dam 56.1 m / s , i n the period o f 20 years 1953/1972. Concluded i n 1974, i t was b u i l t t o i r r i g a t e an agea o f 93000 ha and above a l l t o assure a r e g u l a t e d f l o w o f 80 m / s a t Matala; however, this d u t y has n o t been s a t i s f a c t o r i l y c a r r i e d o u t y e t , due t o t h e i r r e g u l a r working o f t h e e x i s t i n g discharge. I n t h e f u t u r e , when the level o f consumption i s j u s t i f i a b l e , t h e scheme w i l l be completed w i t h a power s t a t i o n , f i t t e d w i t h three generating u n i t s w i t h a nominal c a p a c i t y of 15 MW each one, remaining one u n i t as a r e s e r v e . Both M a t a l a and Gove have s e r i o u s problems concerning s a f e t y . The 29 g a t e s o f t h e s p i l l w a y of t h e M a t a l a dam cannot be open because t h e y a r e embarrassed due t o t h e s h i f t i n g s o c u r r e d i n the s t r u c t u r e ; t h e same happens t o t h e t h r e e gates o f t h e s p i l l w a y o f Gove dam, as a r e s u l t o f sabotage i n 1986. Furthermore s e r i o u s p e r c o l a t i o n problems remain a t t h e Gove dam. I t i s u r g e n t t o open t h e s p i l l w a y g a t e s o f t h e Gove dam i n o r d e r t o a v o i d , i n t h e occurrence o f a s e r i o u s f l o o d , n o t o n l y t h e r i s k o f t h e water pass over t h e dam and consequently i t s d e s t r u c t i o n , b u t a l s o d i s a s t r o u s damages a t t h e dam and power s t a t i o n o f Matala; t h i s c o u l d endanger t h e s u p p l y o f energy t o t h e a l l Southern System and p u t t h e l i f e o f t h e p o p u l a t i o n l i v i n g downstream i n s e r i o u s r i s k . Consequently i t i s v i t a l and u r g e n t t h a t ENE p u t t h e n e e d f u l s o l u t i o n s f o r t h e s e s e r i o u s problems a f f e c t i n g t h e dams o f Matala and Gove i n p r a c t i c e , a t t h e p r e s u p p o s i t i o n t h a t t h e l a s t one c o u l d be under i t s r e s p o n s i b i l i t y and a d m i n i s t r a t i o n , which is j u s t i f i a b l e once i t i s i n t e n d e d t o b u i l d a power s t a t i o n t h e r e i n t h e f u t u r e , as i t was mentioned above. THERMAL POWER PLANTS . NAMIBE, w i t h an i n s t a l l e d c a p a c i t y of 11.5 MW f i t t e d w i t h two d i e s e l u n i t s w i t h t h e nominal c a p a c i t y o f 5.75 MW each one, i n s t a l l e d i n 1980, i t i s t h e o n l y a l t e r n a t i v e o f supply t o t h e Southern System i n t h e case o f M a t a l a ' s u n a v a i l a b i l i t y . P r e s e n t l y o n l y one u n i t i s o p e r a t i n g , h a v i n g generated 3.2 G Wh i n 1989. - . Lubango, w i t h an i n s t a l l e d c a p a c i t y of 3.6 MW i n d i e s e l units w i t h t h r e e o f nominal c a p a c i t y o f 0.4 MW each one and t w e l v e of 0,2 MW each one. Presently a l l the u n i t s are out o f operation, t h e g e n e r a t i o n h a v i n g been i n 1989 o f 2.5 GWh. On t h e whole, t h e S.EG.S. generated o n l y 49 G W h i n 1989, which means 5.8% o f t h e t o t a l g e n e r a t i o n o f Angola ( T a b l e 3 f r o m ANNEX 1, pag. 4 ) ; i n 1989 t h e peak o f t h e system, r e l a t e d t o g e n e r a t i o n , was - around 10 MW, due t o t h e p r e s e n t s i t u a t i o n of suppressed demand L e s t i m a t e d a t 25%. 2 - LEAST-COST EXPA NSION PLAN (L.C.E.P.) CF THE N.EG.S. ) 2.1- ----------------- BASIS HYPOTHESIS The L.C.E.P. of the N . E G . S . was established with base on the following pressuppositions: A - Plan Horizon: year 2015, starting in 1993 r B - Initial composition of the generating system: . two gas turbines in Luanda with available capacities of 20 and 30 MW, respectively; . hydro power station of Cambarnbe, with four generating units totally rehabilitated until the end of 1992, assuring from this date onwards a capacity of 3x45=135MW at 100% of the time, remaining one unit as reserve; . hydro power station of Mabubas unavailable. C - Projects candidates to the system expansion: . the hydroelectric project of Capanda: in view of the present phase of its construction, on the river Kwanza upstream of Cambarnbe, even though under a economical viewpoint, its integration on the system is away from the optimal path of its expansion, this project was considered as unavoidable; however it has been considered in different alternative hypothesis, namely concerning the schedule of the commissioning dates of the four units with a nominal capacity of 130 MW each one, totalizing an installed capacity of 520 M W ; . the heightening of Cambambe dam: around 20 metres, as had always been foreseen, the installed capacity increasing from 4x45=180 MW to 4x65=260 M W ; however, this work, for which is expected a time of five years, requires a previous observation campaign about the present condition and the behaviour of the structure that forces the installation of equipments of measure, d u r i n g a record period of time with statistical meaning which is estimated at three or four years; so it is not possible to consider the heightening of the dam finished before 8 or 9 years, at least, and this if an immediate decision is taken. Therefore this action is only considered feasible after the construction of Capanda; . the construction of a second power station at Cambambe, fitted with generating units with 130 M W of nominal capacity; . due to its small dimension and the kind of problems that affect all the scheme, the reintegration of the hydro power station of Mabubas in the N.E.GS. was not considered. v D - C h a r a c t e r i s a t i o n o f t h e h y d r o e l e c t r i c power p l a n t s : On Tables 1 and 2 from ANNEX 2, t h e monthly i n f l o w s t o t h e h y d r o e l e c t r i c power p l a n t s o f Capanda and Cambambe, during a p e r i o d o f 20 years from 1953 t o 1972, a r e .shown; e q u a l l y , the i n f l o w s t o t h e r e s t o f t h e hydro power p l a n t s t h a t w i l l be c i t e d i n t h e p r e s e n t r e p o r t .(Cacombo, Lomaum, B i 6 p i 0 , Gove and M a t a l a ) a r e g i v e n on Tables 3, 4 , 5 , 6 and 7 from t h e same ANNEX 2. On Tables 8 , 9 and 10 t h e c h a r a c t e r i s a t i o n o f t h e r e s e r v o i r s , t h e corresponding h e i g h t s o f e v a p o r a t i o n and t h e c h a r a c t e r i s a t i o n o f t h e power s t a t i o n s a r e r e s p e c t i v e l y shown. E - Scenarios o f t h e demand e v o l u t i o n : On t h e c o n t a c t s e s t a b l i s h e d w i t h t h e a d m i n i s t r a t i o n s o f t h e e n t e r p r i s e s r e s p o n s i b l e f o r t h e o p e r a t i o n o f t h e N o r t h e r n System (SONEFE) and t h e C e n t r a l and Southern Systems (ENE) t h e f a c t was emphasised t h a t a t t h e p r e s e n t c o n t e x t o f l i v i n g i n Angola i t i s p r a c t i c a l l y i m p o s s i b l e t o c a r r y o u t medium and l o n g range expansion p l a n s , due e s s e n t i a l l y t o t h e f o l l o w i n g f a c t o r s : - conscience of t h e e x i s t e n c e of a suppressed demand o f an unknown b u t s i g n i f i c a n t magnitude, - i n e x i s t e n c e o f a c r e d i b l e census o f t h e p o p u l a t i o n , - i n e x i s t e n c e o f s t a t i s t i c s about t h e economic a c t i v i t y i n t h e country. Consequently, the estimates concerning t h e evolution of consumption a r e done o n l y f o r t h e s h o r t range ( 1 o r 2 y e a r s ) and t h e y a r e j u s t based on s e n s i b i 1i t y c r i t e r i o n s . B a s i c a l l y , t h e e x i s t i n g p l a n s about t o be c a r r i e d o u t concern t h e r e h a b i l i t a t i o n o f t h e e x i s t i n g equipments which a r e a t inadequate condition o f operation. So, more t h a n t h e i n c e r t i t u d e o f t h e i n s t a l l a t i o n o f a s t a b l e peace on t h e c o u n t r y i n a near f u t u r e , t o e s t a b l i s h s c e n a r i o s o f t h e e l e c t r i c i t y demand e v o l u t i o n a t any range becomes extremely vulnerable. Anyhow, and f o r t h e s t u d y purposes, two s c e n a r i o s o f electricity demand e v o l u t i o n , a t t h e l e v e l o f g e n e r a t i o n , were considerea: . t h e H I G H SCENARIO- equivalent t o the I n t e r m e d i a t e Scenario o f t h e m i s s i o n o f 1987, a d j u s t e d f r o m t h e a c t u a l value v e r i f i e d i n 1989 (695.2 GWh) u n t i l 2000; f r o m t h i s year onwards t h e growth r a t e s o f 7,0% u n t i l 2005, 6,0% u n t i l 2010 and 5,0% u n t i l 2015 were assumed; .the L O W SCENARIO - the I n t e r m e d i a t e Scenario defined in the scope o f t h e p r e s e n t m i s s i o n . DEMAND EVOLUTION SCENARIOS a ) Y E A R HIGH O L W a ) T a b l e 11 f r o m ANNEX 2 These two s c e n a r i o s were subsequently extended i n o r d e r t o a l l o w a b e t t e r a n a l y s i s o f t h e a l l o c a t e d g e n e r a t i o n s by Cambambe and Capanda t i l l t h e l i m i t o f t h e i r g e n e r a t i n g c a p a b i l i t i e s , which a t t h e H i g h S c e n a r i o o c c u r s i n t h e year 2024 f o r a g e n e r a t i o n l e v e l o f 6600 GWh, w h i l e a t t h e Low S c e n a r i o such s i t u a t i o n i t i s o n l y reached about t h e year 2030. F - R e l a t i v e l y t o t h e h y d r o power p r o j e c t o f Capanda t h e following a l t e r n a t i v e h y p o t h e s i s were considered. A l t e r n a t i v e I-Observance o f t h e c o n s t r u c t i o n schedule as i t was (ALT.1) e s t a b l i s h e d by GAMEK ( G a b i n e t e do M6dio Kwanza) w i t h t h e c o n c l u s i o n o f t h e dam,with the t o t a l h e i g h t as d e f i n e d a t t h e p r o j e c t , "HIGH CAPANDA", until the end of 1992, but without the installation of any generating unit; the c o r r e s p o n d i n g c o s t e s t i m a t e i s shown on Table 12 f r o m ANNEX 2. * H e i g h t o f t h e dam about 110 meters. Alternative I1 - Corresponding t o t h e schedule o f GAMEK i n which (ALT.11) t h e U n i t 1, a t t h e b e g i n n i n g o f 1993, and t h e U n i t 2 i n , t h e m i d d l e o f t h e same year, a r e considered i n o p e r a t i o n ; t h e corresponding c o s t e s t i m a t e is shown on Table 13 f r o m ANNEX.2. A l t e r n a t i v e 111- C o n s t r u c t i o n o f a lower dam w i t h t h e s p i l l w a y a t (ALT.111) t h e e l e v a t i o n o f 920.0,* "LOW CAPANDA", u n t i l t h e end o f 1992 b u t w i t h o u t t h e i n s t a l l a t i o n o f any generating u n i t ; t h e corresponding c o s t e s t i m a t e i s on Table 14 from ANNEX 2. * H e i g h t o f t h e dam about 91 meters. Each one o f t h i s a l t e r n a t i v e s was considered a t t h e h i g h and low s c e n a r i o s above mentioned, resulting i n the total six a l t e r n a t i v e s which were s t u d i e d f o r t h e l o n g range expansion o f t h e N.EG.S., c h a r a c t e r i s e d as f o l l o w s : UNITS U1 and U2 i n 1993. ALT.1.A - H i g h Capanda ; H i g h Scenario no ALT.1.B - ; Low no ALT.1I.A - ; High Yes ALT.1I.B - ; Low Yes ALT.II1.A - Low Capanda ; H i g h no ALT.II1.B - ; Low no 2.2.1- METHODOLOGY The e s t a b l i s h m e n t o f the L.C.E.P. was based on the following methodology : A - U t i l i s a t i o n o f the "VALORAGUA" model f o r the simulation o f the optimized operation of a mixed hydro-thermal electricity g e n e r a t i n g system. The model i s o f the s t a t i c type, t h a t i s t o say, i s employed each t i m e t o one o n l y c o n f i g u r a t i o n o f t h e system, c o r r e s p o n d i n g t o a c e r t a i n stage ( y e a r ) o f t h e system e v o l u t i o n (ANNEX 2A). r B - W i t h base on s i m u l a t i o n s c a r r i e d o u t w i t h t h e VALORAGUA model u s i n g a s e r i e s o f monthly i n f l o w s t o t h e h y d r o power p l a n t s f o r a p e r i o d o f 20 years f r o m 1953 t o 1982, f o r stages around t h e years 1995, 2000, 2005, 2010 and 2015, (4. was p o s s i b l e t o e v a l u a t e t h e f i r m c a p a c i t i e s and g e n e r a t i o n s by Capanda w i t h one, two, t h r e e o r f o u r i n s t a l l e d u n i t s , t h e c o r r e s p o n d i n g increments due t o t h e h e i g h t e n i n g o f . t h e Cambambe dam and t h e corresponding v a l u e s i m p u t a b l e t o t h e new u n i t s (U5 and U6) t o be i n s t a l l e d a t t h e new power s t a t i o n o f Cambambe. I n t h e n e x t t a b l e these v a l u e s a r e shown: FIRMED FIRM GENERATION CAPACITY (GWh) (MW) Capanda Unit 1 1195 ( 7 9 5 ) 125 ( 9 5 ) Unit 2 2170 (1450) 250 (180) Unit 3 2350 365 Unit 4 2450 2492** 2935** 2790** 445 Cambambe 4 Units 1080 135 heightning 1385 195 Unit 5 1955 32 5 Unit 6 2440 455 ( * * ) The increments r e s p e c t i n g t h e v a l u e 2450 GWh a r e those v e r i f i e d i n t h e power s t a t i o n o f Cambambe b u t imputable t o t h e r e g u l a t i o n induced by t h e Capanda r e s e r v o i r ; they were computed f r o m s i m u l a t i o n s w i t h Cambambe w i t h o u t Capanda upstream, w i c h l e d t o t h e v a l u e s of f i r m g e n e r a t i o n s o f Cambambe shown on t h i s t a b l e . (...) Values f o r t h e ALT.'s 1II.A and 111.6 b e f o r e t h e h e i g h t e n i n g o f t h e Capanda dam. . -. T (*) I n t h i s study f i r m g e n e r a t i o n energy and f i r m c a p a c i t y a r e d e f i n e d as: Firm generation - t h e p r o d u c i b l e energy i n c r i t i c a l year, t h a t i s , t h e year w i t h 95% o f p r o b a b i l i t y t o t h e overpassed ( i n t h e p r e s e n t case, t h e year 1958); Firm capacity - the available capacity a t t h e month o f t h e c r i t i c a l year w i t h h i g h e r l o a d ( i n t h e p r e s e n t case, December 1958). C - S t a r t i n g w i t h ALT.'S l . A and 1.6, and by comparing t h e f i r m g e n e r a t i o n and t h e f i r m c a p a c i t y o f Cambambe and Capanda w i t h t h e demand o f g e n e r a t i o n and c a p a c i t y from 1993 onwards, the o p p o r t u n i t y t i m e s o f t h e commissioning dates f o r t h e f o u r g e n e r a t i n g u n i t s o f Capanda, o f t h e h e i g h t e n i n g o f t h e Cambambe dam and o f t h e new g e n e r a t i n g u n i t s o f a second power s t a t i o n t o be b u i l t i n Cambambe, were d e f i n e d . I t was f i x e d t h e f o l l o w i n g c r i t e r i o n : f r o m t h e commissioning date o f the f i r s t u n i t o f Capanda onwards, t o assure t h e peak o n l y w i t h t h e f i r m hydro c a p a c i t y , b e i n g assumed however, a d e f i c i t till the l i m i t o f 10%. Nevertheless i t was always k e p t , within the study's horizon, a c a p a c i t y o f 50 MW i n s t a l l e d i n gas t u r b i n e s i n Luanda as emergence r e s e r v e , which e v e n t u a l l y c o u l d c o n t r i b u t e t o s h o r t e r those d e f i c i t s . This w i l l lead t o the replacement, i n a convenient date, o f t h e p r e s e n t t u r b i n e s by two new ones o f 25 MW each, b u r n i n g g a s o i l o r n a t u r a l gas. The ALT.'s 1 I . A and l I . B d i f f e r from de former j u s t because t h e y c o n s i d e r i n o p e r a t i o n t h e u n i t s 1 and 2 o f Capanda i n 1993, in s p i t e o f t h e f i r m g e n e r a t i o n and f i r m c a p a c i t y o f these u n i t s b e i n g o n l y c o n s i d e r e d when necessary f o r t h e system, as founded i n ALT.'s 1 . A and 1 . 8 . The system expansion i s s i m i l a r t o t h e former a l t e r n a t i v e s from t h e commissioning date o f U n i t 3 of Capanda onwards. A t ALT.'s 1II.A and 111.8 the o p p o r t u n i t y times o f the commissioning dates f o r t h e U n i t s 1 and 2 o f Capanda, o f t h e h e i g h t e n i n g o f Cambambe dam and t h e commissioning d a t e f o r t h e U n i t 3 o f Capanda, were searched, b e i n g t h e expansion f r o m t h i s d a t e onwards s i m i l a r t o t h e former a l t e r n a t i v e s . D - On Tables 15, 16, 17, 18,. 19 and 20 o f ANNEX 2 t h e system expansion i s presented i n accordance w i t h i t s foreseen e v o l u t i o n , f o r t h e s i x c o n s i d e r e d a l t e r n a t i v e s , as i t i s shown on t h e two s e t s o f f i v e columns having t h e t i t l e s , r e s p e c t i v e l y , GWh and MW. I n t h e s e t o f t h r e e columns w i t h t h e t i t l e "GENERATION (GWh)/ /WITHOUT INTERCONNECTION", t h e g e n e r a t i o n s a l l o c a t e d on t h e N o r t h e r n System network by t h e power s t a t i o n s o f Capanda and Cambambe a r e shown, which, when h i g h e r t h a n t h e r e s p e c t i v e f i r m g e n e r a t i o n , a r e t h e g e n e r a t i o n s a t t h e average o f t h e twenty h y d r o l o g i c a l regimes s i m u l a t e d . 2.2.2- ANALYSIS OF THE RESULTS From t h e a n a l y s i s o f t h e Tables 15, 16, 17, 18, 19 and 20 o f ANNEX 2 i t i s v e r i f i e d t h a t i s t h e f o l l o w i n g t h e l o n g range expansion i n o r d e r t o meet t h e demands o f c a p a c i t y and g e n e r a t i o n ( e x c e p t f o r ALT.11 i n which was considered t h e commissioning d a t e f o r t h e u n i t s U1 and U2 of Capanda i n 1 9 9 3 , accordingly the schedule o f GAMEK): HIGH SCENARIO, JAM SCENARIO ALT.1.A ALT.1I.A ALT.II1.A ALT.1.B ALT.1I.B ALT.III.0 1993 U1, U2 U1, U2 1996 U1 U1 1998 U2 U1 U1 1999 U2 2002 I U2 2004 U2 2005 U3 U3 U3 2007 2009 U4 U4 U4 1 201 1 I I I U3 U3 U3 201 3 U5 U5 U5 2017 U6 U6 U6 U4 U4 U4 201 9 202 1 U5 I U5 1 U5 1 2025 U6 U6 U6 Ul,U2,U3,U4 - Generating u n i t s o f Capanda U5,U6 - Generating u n i t s o f t h e second power s t a t i o n o f Cambambe ( - H e i g h t e n i n g o f Cambambe dam I- H e i g h t e n i n g o f Capanda dam See Table 2 1 from ANNEX 2 . I n conclusion: - f r o m t h e commissioning date o f t h e U3 o f Capanda the three a l t e r n a t i v e s a r e s i m i l a r f o r t h e same s c e n a r i o ; - passing f r o m t h e High Scenario t o t h e Low Scenario i t i s v e r i f i e d that: . t h e commissioning d a t e o f U1 moves f r o m 1 9 9 6 t o 1 9 9 8 . t h e commissioning d a t e o f U2 moves from 1 9 9 9 t o 2 0 0 4 a t t h e ALT.1, b u t f r o m 1 9 9 8 t o 2 0 0 2 a t t h e ALT.111 . t h e h e i g h t e n i n g o f Capanda dam a t t h e ALT.111 moves from 2 0 0 2 t o 2007. . t h e commissioning d a t e o f U 3 moves f r o m 2 0 0 5 t o 2 0 1 1 . t h e commissioning d a t e o f U 4 moves f r o m 2 0 0 9 t o 2 0 1 7 . t h e h e i g h t e n i n g o f Cambambe dam moves from 2 0 1 1 t o 2 0 1 9 . t h e commissioning d a t e o f U 5 moves f r o m 2 0 1 3 t o 2 0 2 1 . t h e commissioning d a t e o f U6 moves f r o m 2 0 1 7 t o 2 0 2 5 - a t t h e H i g h S c e n a r i o new g e n e r a t i o n c e n t r e s a r e r e q u i r e d f r o m t h e year 2 0 2 0 onwards. 2.2.3- COST ESTIMATES AND INVESTMENT PLANS The c o s t e s t i m a t e s c o n c e r n i n g t h e A L T . ' s I,I 1 and I11 ccns:derea f o r t h e power p l a n t o f Capanaa,which a r e snown on T a b i e s 1 2 , 13 and 14 f r o m ANNEX 2, were e l a b o r a t e d f o r a system o f prices r e f e r r e d t o t h e end o f 1989, as w e l l as t h e e s t i m a t e s c o n c e r n i n g the heightening of Cambambe dam and t h e c o n s t r u c t i o n o f a new power s t a t i o n i n t h i s h y d r o scheme; I n a f i r s t phase, i t w i i i be f i t t e d w i t h two u n i t s , w i t h t h e nominal c a p a c i t y o f 130 M k each one, whose c o s t r e a c h t h e f o l l o w i n g amounts in m~llions of USD ( p a g . 2 2 and 23 f r o m ANNEX 2 ) . Heightening o f Cambambe dam ...............................180.0 New power s t a t i o n (13 phase: 2x130 MW) - C.C. ...... 151.0 - EQ. ...... 177.0 328.0 TOTAL .......... 508.0 M.USD C.C. - C i v i l construction EQ. - Equipment On t a b l e s 22, 23, 24, 25, 26 and 27 from ANNEX 2, the corresponding investment p l a n s , as w e l l as t h e c o r r e s p o n d i n g o p e r a t i o n and maintenance c o s t s ( i n accordance w i t h t h e t i m i n g o f t h e c o m m i s s i o n i n g d a t e s o f t h e d i f f e r e n t g e n e r a t i n g u n i t s and o f t h e h e i g h t e n i n g of t h e dams, as t h e y were p r e s e n t e d on t a b l e s 15, 16, 17, 18, 19 and 20 and summarized on T a b l e 21 of t h e same annex) a r e shown i n d e t a i l . On t h e same t a b l e s 22 t o 27 a r e a l s o p r e s e n t e d t h e f l o w s o f the g e n e r a t i o n s a l l o c a t e d by Capanda and t h e second power s t a t i o n o f Cambambe a t t h e h y p o t h e s i s w i t h o u t interconnection o f the N o r t h e r n System t o t h e C e n t r a l and S o u t h e r n Systems ( f r o m t a b l e s 15 t o 20 o f ANNEX 2 ) . 2.2.4- LONG RUN MARGINAL COSTS (L.R.M.C.) The L.R.M.C. f r o m Capanda a r e d e f i n e d as t h e l e v e l i z e d g e n e r a t i n g costs during i t s l i f e t i m e , w h i c h i s assumed t o be o f 50 y e a r s f r o m t h e c o m p l e t i o n o f t h e dam c o n s t r u c t i o n ( e n d o f 1 9 9 2 ) . So d i s c o u n t i n g , t o t h e b e g i n n i n g of 1990, t h e f l o w s p r e s e n t e d on t a b l e s 22 t o 27 f r o m ANNEX 2, u s i n g t h e d i s c o u n t r a t e s o f 10, 12 and 15%, i t i s p o s s i b l e t o compute t h e L.R.M.C. f r o m Capanda, f r o m Cambambe ( c o n c e r n i n g o n l y t h e second power s t a t i o n ) and f r o m the set Capanaa-Cambambe, at the hypcthesis w 1 t!7ou: interconnection. Such v a l u e s a r e shown on t a b l e s 2 8 , 2 9 , 30, 31, 3 2 and 3 2 ircm ANNEX 2 ; a t t h e b o t t o m o f T a c l e 21 from ANNEX 2 a r e surnmerlzec those values ( i n cents of USD p e r kWh) for tne set Capanda-Cambambe, j o i n t l y w i t h t h e c o r r e s p c n a i n g t o t a l d i s c a u n t e c c o s t s ( i n M . U S D ) , f o r ' t h e sqx a l t e r n a t i v e s . L o o k i n g o n l y a t t h e Capanda c o s t s i t i s v e r i f ~ e d t h a t t h e minimum c o s t s c o r r e s p o n d t o t h e ALT.111 (LOW CAPANDA u n t i l 2002 o r 2007 according t o the s c e n a r i o s ) ; however, the corresponding generetion i s lower t h a n t h a t o f t h e ALT.l resulting for this a l t e r n a t i v e t h e minimum l e v e l i z e d g e n e r a t i n g c o s t s . C o n s e q u e n t l y i t i s c o n s i d e r e d t h a t t h e L.C.E.P. f o r the Ncrthern E l e c t r i c System c o r r e s p o n d s t o t h e ALT.1 with the followins L.R.M.C. ( i n c e n t s o f USD/kWh): DISCOUNT RATE CAPANDA H 12.59 17.86 28.67 L 18.10 26.91 46.16 CAMBAMBE H 5.98 7.68 10.92 L 5.54 7.11 9.98 CAPANDA + L 1 1 . 6 4 16.99 CAMBAMBE H - High Scenario L - Low S c e n a r i o 2.2.5- CONCLUSIONS AND RECOMMENDATIONS The L.C.E.P. for t h e N.E.G.S. corresponds t o t h e b e s t s t r a t e g y f o r t h e development of t h e hydro p r o j e c t o f Capanda which c o n s i s t s on t h e ALT.1 l e a d i n g t o t h e minimum g e n e r a t i o n c o s t s p e r kwh (between 12.59 c e n t s o f USD, f o r t h e d i s c o u n t r a t e o f 10% and t h e H i g h S c e n a r i o , and 46.16 c e n t s o f USD, f o r t h e d i s c o u n t rate o f 1 5 % and t h e Low S c e n a r i o ) . Capanda h y d r o p r o j e c t , j o i n t l y w i t h t h e p r e s e n t power s t a t i o n o f Carnbambe, i s enough t o meet t h e demand on t h e N o r t h e r n system t i l l 2010, a t t h e High Scenario, o r till 2018 a t t h e Low Scenario. I n t h i s c o n t e x t t h e h e i g h t e n i n g o f Cambambe dam and i t s secona power s t a t i o n a r e v e r y q u e s t i o n a b l e because t h e y a r e o n i y p u t in p e r s p e c t i v e a t t h e y e a r s 2011 o r 2019, a c c o r d i n g t h e scenarios. ' h i s r a i s e t h e q u e s t i o n o f t o know i f i t would be j u s t i f i a b l e to , e a l i z e t h o s e works a t a moment when t h e dam i s a l r e a d y more t h e n 0 y e a r s o l d and s u g g e s t t h e r e s e a r c h of b e t t e r a l t e r n a t i v e s . So, i t i s recommended t h e achievement o f p r e f e a s i b i l i t y s t u d i e s , with a satisfactory t e c h n i c a l and b u d g e t a r y c h a r a c t e r i z a t i o n , c o n c e r n i n g some h y d r o p r o j e c t s whose d i m e n s i o n seems t o be more adequate t o t h e s c a l e o f t h e e l e c t r i c systems o f Angola, such as, f o r instance: M i d d l e Kwanza B a s i n - Zenzo I 1 ( 1 5 0 MW; 670 GWh) Queve Basin - Caivole ( 7 0 MW; 325 GWh) and C a c h o e i r e s do B i n g a (195MW; 960 GWh) Longa Basin - Quissula ( 1 1 0 MW; 538 GWh), Cassongo (110 MW, 517 GWh), Lungo ( 5 0 MW; 233 Gwh) and Murimbo ( 1 7 0 MW; 818 GWh) 2.3.1- IMPACT ON THE L.R.M.C. OF THE N.EG.S. W i t h t h e hydro power p l a n t s o f Cambambe and Capanda i n operation surplus of'generations are v e r i f i e d i n t h e Northern System c o m p a r a t i v e l y t o t h e demand, even i n t h e High Scenario, u n t i l t h e year 2025. This f a c t suggests an a n a l y s i s on t h e i n t e r e s t o f t h a t system i n t e r c o n n e c t i o n t o t h e C e n t r a l and Southern Systems which would be m a t e r i a l i z e d by means o f a t r a n s m i s s i o n l i n e o f 220 k V , from t h e s u b s t a t i o n o f Cambambe t o Lubango, passing through Gabela and B i o p i o ; w i t h a t o t a l e x t e n s i o n o f 570 Km and a p e r i o d of c o n s t r u c t i o n o f 4 years i t s t e c h n i c a l c o s t , a t p r i c e s o f t h e end o f 1989, i s e s t i m a t e d a t 102.6 m i l l i o n s o f USD* (see Map o f ANNEX 2 ) . The s t u d y was performed o n l y f o r t h e h y p o t h e s i s o f t h e High Scenario o f power demand i n t h e t h r e e systems t o which corresponds t h e e v o l u t i o n presented on T a b l e 1 from ANNEX 3 ; once more t h e VALORAGUA model was used, which a l l o w s t h e a n a l y s i s o f several mixed hydro-thermal systems, i n t e r c o n n e c t e d by a t r a n s m i s s i o n network w i t h a s i m p l i f i e d r e p r e s e n t a t i o n (ANNEX 2A), h a v i n g been analysed t h e systems s t a g e s f o r t h e years 1996, 2005 and 2015. The s t u d y was c a r r i e d o u t on t h e p r e s u p p o s i t i o n t h a t a l l t h e equipment o f g e n e r a t i o n nowadays u n a v a i l a b l e , or a t precarious c o n d i t i o n s o f o p e r a t i o n , would be r e h a b i l i t a t e d i n o r d e r t o g e t ready, f r o m 1994 onwards: - a l l t h e thermal g e n e r a t i o n equipment, namely, t h e gas turbines o f Biopio.(22.8 M W ) and Huambo (10 MW), and the diesel units of L o b i t o (20.0 M W) and Namibe (11.5 MW); - t h e h y d r o e l e c t r i c power p l a n t (H.P.P.) o f Lomaum f i t t e d w i t h t h e two new u n i t s w i t h t h e nominal c a p a c i t y o f 15 MW each one and t h e former one w i t h t h e same nominal c a p a c i t y as a reserve; - t h e H.P.P. of B i o p i o f i t t e d w i t h f o u r u n i t s w i t h a nominal c a p a c i t y of 3.6 MW each one, completly r e h a b i l i t a t e d , o r new ones w i t h t h e same c a p a c i t y , remaining one as reserve; - t h e H.P.P. of Matala f i t t e d w i t h one new u n i t o f a nominal c a p a c i t y of 13.6 MW and t h e two former u n i t s , o f t h e same nominal c a p a c i t y , a f t e r rehabi 1 it a t i on, r e m a i n i n g one o f these as reserve. - t h e Gove dam w i t h i t s d i s c h a r g e equipments ( * ) Taking as b a s i s 180,000 USD per Km. A t these c o n d i t i o n s , t h e f o l l o w i n g e v o l u t i o n s arose f o r the c o m p o s i t i o n o f t h e C e n t r a l and Southern Systems, w i t h i n t h e s t u d y h o r i z o n ( y e a r 2015): C.EG.S. - Gas t u r b i n e o f B i o p i o w i t h 22.8 MW, a v a i l a b l e from 1994 onwards - Gas t u r b i n e o f Huambo w i t h 10.0 MW, a v a i l a b l e f r o m 1994 onwards - D i e s e l u n i t s o f L o b i t o w i t h 20.0 MW, a v a i l a b l e f r o m 1994 onwards - H.P.P. of Lomaum, f i t t e d w i t h 45 MW f r o m 1994 onwards and w i t h 65 MW f r o m 2004 onwards by u p r a t i n g w i t h t h e two f o r m e r u n i t s w i t h 10 MW o f nominal c a p a c i t y each one, a f t e r r e h a b i l i t a t i o n - H.P.P. of Biopio f i t t e d with 14.4 MW, f r o m 1994 onwards - H . P . P . o f Cacombo o n l y w i t h r e g u l a t i n g purpose f r o m 2009 onwards and f i t t e d w i t h two u n i t s o f 12 MW each one, f r o m 2014 onwards. S.EG.S. - Gas t u r b i n e o f Namibe w i t h 11.5 MW, a v a i l a b l e from 1994 onwards - H.P.P. o f Gove o n l y w i t h r e g u l a t i n g purpose from 1994 onwards and f i t t e d w i t h two u n i t s o f 15 MW each one f r o m 2014 onwards - H.P.P. o f M a t a l a f i t t e d w i t h 40,8 MW f r o m 1994 onwards. On T a b l e 15 f r o m ANNEX 2 on t h e l a s t s e t o f t h r e e columns e n t i t l e d "GENERATION (GWh) - WITH INTERCONNECTION" and on t h e r i g h t hand s i d e o f T a b l e 22 f r o m t h e same annex a r e shown t h e g e n e r a t i o n s o f Cambambe ( D ) 'and Capanda, a t t h e above mentioned c o n d i t i o n s . As p r e v i o u s l y , d i s c o u n t i n g t h e s e g e n e r a t i o n f l o w s , supposed t o be c o n s t a n t f r o m f r o m 2025 onwards, t o t h e b e g i n n i n g o f 1990, and f o r t h e r a t e s o f 10, 12 and 15%, new v a l u e s f o r t h e L.R.M.C. a r e o b t a i n e d w h i c h a r e shown on T a b l e 28 f r o m ANNEX 2. As consequence o f t h e i n t e r c o n n e c t i o n i t i s verified that f o r ALT.1.A t h e L.R.M.C. a t t h e N.EG.S. decrease: . around 6,4% a t Capanda, independently o f the discount rates . between 18 and 23% a t Cambambe, a c c o r d i n g t o t h e d i s c o u n t rates . 7.8% f o r t h e s e t Capanda-Cambambe, independently o f t h e d i scount r a t e 2.3.2- ECONOMICAL ANALYSIS On t a b l e s 34, 35 ana 36 f r o m ANNEX 2 a r e s n o r t l y snown tne r e s u l t s with i n t e r e s t f o r the analysis i n considera~ion. The o b t a i n e d r e s u l t s show c l e a r l y t h a t t h e N.EG.S., a l ~ h c u g n b e g i n n i n g i n 1996 w i t h a d i s c r e e t c o n t r i b u t i o n f c r t h e C . E . 2 . S . and S . E G . S . , can a s s u r e v e r y i m p o r t a n t power t r a n s f e r s f o r tnese systems, m a i n l y between 2000 and 2023 year i n w h ~ c hsuch s u p p o r t w i l l f i n i s h aue t o t h e s a t u r a t i o n o f t h e g e n e r e t i o n o f t h e s e t Capanda/Cambanbe t o f u l f i l t h e requirements o f t h e Nortnern System s u p p l y . For i n s t a n c e , f o r t h e C.EG.S. i n t h e year 2015 (and f o r a d i s c o u n t r e t e o f 10%) t h e s i t u a t i o n i s t h e f o l l o w i n g : Thermal G e n e r a t i o n Fuel c o n s u m p t i o n ( * ) i n average year (GWh) (M. U S D ) without interconnection 414.2 w i t h interconnection 80.0 Required c a p a c i t y i n G.T. besides Correspondent the existent, a t annual charge ( x * ) c r i t i c a l period (DEZ.58) M ( W1 (M. USD) without interconnection 140.8 w i t h interconnection 56.1 So, f o r t h e C . E G . S . , a t t h e year 2015 and t o t h e d i s c o u n t rate of l o % , t h e e x i s t e n c e of t h e i n t e r c o n n e c t i o n enables a s a v i n g o f about 39 m i l l i o n s o f USD. It results that, g l o b a l l y , t h e worth of the interconnecti'on is, i n M.USD: DISCOUNT R A T E 10% 12% 15% (*) For t h e gas t u r b i n e s i t was assumed a v a r i a b l e c o s t between 9.0 and 10.7 c e n t s o f USD p e r kwh. (**I Annual f i x e d charge o f 6 3 , 73 and 89 USD per kw, r e s p e c t i v e l y , f o r t h e r a t e s o f 10, 12, and 15%. I As i t can be seen on T a b l e 15 from ANNEX 2 t h e v a l u e s f o r 2015 c o r r e s p o n d t o a t r a n s i t of a b o u t 600 GWh from the Northern System t o C e n t r a l and S o u t h e r n Systems. On t h e same t a b l e i t can be o b s e r v e d t h a t t h i s s i t u a t i o n goes on u n t i l t h e year 2022, d e c r e a s i n g t o 300 G Wh i n 2023 and t o z e r o i n 2024, y e a r i n which t h e g e n e r a t i o n demand a t t h e N o r t h e r n System (6600 GWh) s a t u r a t e s t h e a v e r a g e annual g e , n e r a t i o n o f Cambambe and Capanaa. So, c o n s i d e r i n g t h e v a l u e o f 2015 v a l i d up t o 2022, h a l f o f t h a t v a l u e f o r 2023 and z e r o t o 2024, and i n t e r p o l a t i n g linearly between t h e v a l u e s o b t a i n e d f o r 1996, 2005 and 2015, a f l o w is d e f i n e d which, discounted f o r t h e r a t e s 10, 12 and 15% t o t h e b e g i n n i n g o f 1996, g i v e s t h e f o l l o w i n g v a l u e s f o r t h e w o r t h o f the interconnection: RATE 1 OX 196.0 M. USD 12% 159.7 M. USD 15% 121.7 M. USD On t h e o t h e r hand, and as i t was a l r e a d y s a i d , t h e c o s t o f t h e l i n e i s e s t i m a t e d i n 102.6 USD, b e i n g f o r e s e e n a c o n s t r u c t i o n p e r i o d of 4 years. So, i t s total cost, discounted t o ' the b e g i n n i n g o f 1996, r e s u l t s a p p r o x i m a t e l y e q u a l t o : RATE C o n s i d e r i n g t h e annual c h a r g e s w i t h t h e t r a n s m i s s i o n l i n e m a i n t e n a n c e o f a b o u t 3% o f i t s cost, that is, 0.03x102.6=3.78 M.USD, t h e c o r r e s p o n d i n g d i s c o u n t e d t o t a l v a l u e s t o t h e b e g i n n i n g o f 1996, and f o r a p e r i o d o f 28 y e a r s ( f r o m 1996 up t o 2 0 2 3 ) , a r e the following: RATE So, the discounted net values of the worth of the i n t e r c o n n e c t i o n are: RATE 10% 12% 15% I t f o l l o w s t h a t the i n t e r c o n n e c t i o n o f t h e N o r t h e r n System t o t h e C e n t r a l and Southern System, a t t h e c o n s i d e r e d s c e n a r i o , i s i n t e r e s t i n g under a s t r i c t l y economic v i e w p o i n t , f o r the d i s c o u n t r a t e s o f 10 and 12%, b u t n o t j u s t i f i a b l e f o r t h e r a t e o f 15%. A d d i t i o n a l l y , such i n t e r c o n n e c t i o n enables t o postpone l a r g e investments a t t h e C e n t r a l and Southern Systems f o r s e v e r a l years, as i t i s analysed on Chapter 3 . However, that i n t e r c o n n e c t i o n can be s u b j e c t t o some t e c h n i c a l r e s t r a i n t s which must be c a r e f u l l y analysed as, for i n s t a n c e , i t s c o n t r i b u t i o n f o r t h e r e l i a b i l i t y o f t h e Northern, C e n t r a l and Southern Systems o p e r a t i o n . 3 - EXPANSION PLANS OF THE C.EG.S. AND S.EG.S. AS ISOLATED SYSTEMS v On c h a p t e r 2.3 was d e f i n e d t h e e v o l u t i o n o f t h e c o m p o s i t i o n of t h e C.EG.S. and S . E G . S . , between 1995 and 2015, assuming the i n t e r c o n n e c t i o n o f t h e N o r t h e r n System t o t h e C e n t r a l and Southern Systems. However, i n case o f ' such i n t e r c o n n e c t i o n n o t b e i n g c l e a r l y a d v i s a b l e under a t e c h n i c a l p o i n t o f view, i t i s i m p o r t a n t t o analyse t h e expansion o f t h e s e two systems, a l t h o u g h f o r a s h o r t e r h o r i z o n , 1995-2005, a t t h e h y p o t h e s i s of r e m a i n i n g i s o l a t e d , as i t happens , nowadays. For t h i s purpose o n l y t h e H i g h S c e n a r i o o f t h e demand e v o l u t i o n , p r e s e n t e d on T a b l e 1 from ANNEX 3, was c o n s i d e r e d . This scenario corresponds t o t h e I n t e r m e d i a t e S c e n a r i o assumed a t t h e M i s s i o n o f 1987 as a l r e a d y mentioned, o n l y r e c t i f i e d from t h e values a c t u a l l y v e r i f i e d i n 1987 a t t h e C e n t r a l and Southern Systems. I n consequence o f f a i l u r e s o f several equipments o c c u r r e d i n 1988 and 1989, the - g e n e r a t i o n v a l u e s of t h e s e years cannot be used as a b a s i s f o r a demand f o r e c a s t because t h e y correspond t o a s i t u a t i o n i n which t h e demand has n o t been met. I t was assumed t h a t i n 1995 t h e c o m p o s i t i o n of t h e C . E G . S . and t h e S . E G . S . were e x a c t l y t h e same o f t h o s e d e f i n e d on c h a p t e r 2.3. The s i m u l a t i o n s c a r r i e d o u t f o r t h e years 1995, 2000 and 2005, by means o f t h e u t i l i z a t i o n o f VALORAGUA model, l e d t o t h e r e s u l t s -- s h o r t l y p r e s e n t e d on T a b l e s 2 and 3 from ANNEX 3, whose a n a l y s i s I e suggests t h e f o l l o w i n g remarks: - A t the C.EG.S, t h e dam o f CACOMBO o n l y w i t h t h e r e g u l a t i o n purpose i s needed i n 2000 and i t s power s t a t i o n , f i t t e d w i t h 2x12 MW, i n 2003, w h i l e , i n t h e case o f i n t e r c o n n e c t i o n t o t h e N o r t h e r n System, t h o s e d a t e s were, r e s p e c t i v e l y , 2010 and 2015 ( T a b l e 2 f r o m ANNEX 3 and Table 34 f r o m ANNEX 2 ) . n a d d i t i o n t o t h i s , i n view o f t h e magnitude o f t h e s h o r t a g e o f 'nergy i n d r y year (1958) between 1997 and 1999 and a t t h e year 005, i t i s e s s e n t i a l t o i n s t a l l t w o new gas t u r b i n e s , one w i t h t h e nominal c a p a c i t y of 25 MW, i n 1997, and t h e o t h e r w i t h 30 MW, i n 1998, so t h a t t h e u t i l i z a t i o n of t h e t h e r m a l u n i t s i n t h a t d r y year w i l l be around 1200 and 1600 h o u r s . - A t t h e S.EG.S., t h e power s t a t i o n t o be i n s t a l l e d a t t h e H.P.P. o f GOVE i s n e e d f u l a t 1999 f i t t e d w i t h 2x15 MW, and a t 2003 w i t h 3x15 MW w h i l e i n case of i n t e r c o n n e c t i o n t o t h e N o r t h e r n System i t would o n l y be r e q u i r e d i n 2015 ( T a b l e 3 f r o m ANNEX 3 and Table 34 f r o m ANNEX 2 ) . T h i s means t h a t , i n case o f t h e C e n t r a l and Southern System - r e m a i n i n g i s o l a t e d , i t w i l l be needed t o a n t i c i p a t e i n v e s t m e n t s t h a t a r e e s t i m a t e d as f o l l o w s : CACOMBO - Dam ...................... 150.0. M.USD Power s t a t i o n (3x12 MW) ... 48.0 M.USD Gas t u r b i n e ( 2 5 MW) .. ... . 11.0* M.USD Gas t u r b i n e ( 3 0 MW) .. ... . 13.2* M.USD GOVE - Power S t a t i o n (3x15 MW) .. 60.0 M.USD Taking i n t o account t h e r e s p e c t i v e investment p l a n s a t t h e h y p o t h e s i s w i t h and w i t h o u t i n t e r c o n n e c t i o n , i t i s v e r i f i e d t h a t , for discounted values t o t h e beginning of 1995, t h e sustenance o f t h e C.EG.S. and S.EG.S. isolated "versus" the hypothesis with i n t e r c o n n e c t i o n means t h e f o l l o w i n g i n c r e m e n t o f c o s t s c o n c e r n i n g t h e i n v e s t m e n t s u n t i l t h e y e a r 2003: RATE C.EG.S. S.EG.S. TOTAL as i t f o l l o w s from T a b l e 4 of ANNEX 3 ; t h i s f i g u r e s added t o t h e c o r r e s p o n d i n g ones c o n c e r n i n g t h e w o r t h o f t h e interconnection (see nQ 2.3.2) a r e b i g enough t o j u s t i f i e t h e i n t e r c o n n e c t i o n u n l e s s s e r i o u s t e c h n i c a l r e s t r a i n t s render i t u n f e a s i b l e . I Concerning t h e b e t t e r s t r a t e g y f o r the evolution o f the thermal components i t must be observed t h a t : - once t h e gas t u r b i n e o f Huambo does n o t o p e r a t e a t t h e most suitable conditions, due t o t h e a l t i t u d e a t which i t i s i n s t a l l e d , i t seems j u s t i f i a b l e t o t r a n s f e r i t t o Namibe, by change w i t h the diesel units of Namibe and Lobito ( 1 1 , 5 + 20,O = 31,5 M W ) , a f t e r t h e n e e d f u l r e h a b i l i t a t i o n , t o Huambo, where t h e y w i l l be needed around t h e y e a r 2005. - t h e two new t u r b i n e s t o be i n s t a l l e d a t t h e C.EG.S., eventually b u r n i n g n a t u r a l gas, must be l o c a t e d a t t h e a r e a o f Benguela and Lobi t o . ( * ) T a k i n g as b a s i s 440 USD p e r kW. ANNEX 1 Pag . I / 4 T A B 1 E 1 I N S T A L L E D AND A V A I LA BLE GENERATING CAPACITY I N JAN.90 (Part 1 ) SYSTEM NAME TYPE NUMBER OF UNITS CAPACITY DATE OF DATE OF AND OF AND UNIT POWER (W) CO)RIISSION. UNAVAILABI . PROVINCE PLANT (a) (W INSTALLED AVAILABLE MONlH/VEAR INDISPON. Nofth Kuanza N. Cambubo H 2x45+2x45 180.0 135.0 1963,1973 Bengo Mabubae H 2x3+2x5.9 17.8 --- 1953,1959 2/1986 Luanda Luanda TG1 GT 1x25.6 25.6 20.0 1980 Luanda TG2 GT 1x31.2 31.2 30.0 8/1985 Subtotal 254.6 185.0 -ml Bengwla L O MU H 2xlO+lx15 35.0 --- 1964.1 972 3/1983 " Biopio H 4x3.6 14.4 10.8 1957 " Biopio GT 1x22.8 22.8 --- 2/1974 1988 Biopio D 2x1.5 3.0 --- 1982 Lob it o D 4x5 (b) 20.0 5.0 1986 1989 Huambo Hulabo GT 1x10 (c) 10.0 10.0 1981 HU~UI~O D 4~0.8+2~0.85 4.9 0.8 1953-1986 Subtotal 110.1 26.6 SarLh Hu > I t 3 L m u - 4 4 0 3 uCTa=n'n ANNEX 2 Pag. 13/39 T A B L E 13 CAPANDA INVESTMENT PROGRAM - ALT.11 ( i n thousands o f U S 3 ) I CAPANDA 1 -. . I IPS! I t i.-. :: ;:35 4 . ! 1 .; I: .i .: ..., : I .. ; ; -, 2- I I ! -... I i * I . . . -,.-- r . ...-.I. - . , I I C I V I L CONSTRUCTION f i I V E E 31 i E ? $ I a H i 5kN Y A T C Y' { ;S FOwE3 57,:-ION -. .- ' -. -1 - ; ! SLi!Sid'I?N ! I EPUIPMENTS TJE:I!ii: :EhEid-t;; ! :?) 2 't I . ... .:.,:I: I; I:.: *:- ! i -- ;;.;:: , 4 1nAN5=5?!!Ei5 i 7 j . :- . , ... , . . .. ... I - ' 9 su~:;~i:G'( . ... 3'1.: j .. .. ... - a . 5.: I 1 - .- - - , - . . 8 . : , 1.: . -.. 1 S E l Y i C E j TJE j E B ' i . F.t'i!j,IlSlli;ANCEf,ETC I#;I)EC' Cg :;S I - ... c.:: !.:.. IT!:: i,i!t I T O T A L -- - - . ,. 7 1 : ;,53: J;,i[: :?!::: Source: GAMEK - ANNEX 2 Pag. 14/39 T A B L E 14 CAPANDA INVESTMENT PROGRAM - ALT.111 ( i n thousands o f U S D ) I CAPANDA I SUB-TOTA! 1985188 1989 1990 1991 1992 1993 G1 C2 ~EISTIIIIINS OF THE iJAH I i4 PLdHNING/DESlGN SUBSTRUCTURE LUANDA SUBSTRUCTURE CAPANDA URBANIZATION REACTIVATION OF THE SI~E C I V I L CONSTRUCTION RIVER DIVERSION OAH WATERWAYS POWER STATION SUBSTATION EQUIPHENTS TURBINES ( 2 ) GEHERATORS ( 2 ) TRANSFORMERS ( 1 ) SUBSTATION GATES AND HECHAN. EQUIPMENT I INSTALLATION AND TRANSPORTS SERVICES TPE I SERV. FURNAS, INSURANCES,ETC INDIRECT COSTS T O T A L * w i t h o u t REACTlVATIOll OF THE S I T E Source: GAMEK IF- ' I C r . 1 I R I I TABLE 16 HIGH CAPANDA I HIGH SCENARIO -- ALT II . ANNEX 2 GWh MW GENERATION GWh Pag. 16/39 FIRM ENERGY FlRM CAPACITY WITHOUT INTERCONNECTION WITH INTERCONNECTION Year Demand Peak CAM CAP GT TOTAL CAM CAP GT TOTAL TOTAL D CAPANDA TOTAL D CAPANDA 790 790 135 790 790 3.8 138.8 790 30 820 13.6 148.6 1080 U I U 2 - 1080 25.5 160.5 886 1080 1080 41.5 176.5 974 1080 11 1091 50.0 185 1080 1080 1195 2275 26 0 553 669 1080 1195 2275 260 588 78 1 1080 1195 2275 260 626 893 1080 21 70 3250 38 5 568 1088 1080 21 70 3250 38 5 573 1216 1080 21 70 3250 385 578 1336 1080 21 70 3250 385 583 1465 1080 21 70 3250 385 588 1603 1080 21 70 3250 385 593 1751 1080 U3 2350 3430 500 598 191 1 1080 2350 3430 500 683 1976 1080 2350 3430 500 768 2050 1080 2350 3430 500 853 2135 1080 U4 2450 3530 580 938 2229 1080 2450 3530 580 1025 2333 .7 1385 2492 3877 640 1105 25 2420 1385 2492 3877 640 1191 111 2511 US 1955 2935 4890 770 1284 204 2603 1955 2935 4890 770 1384 304 2697 1955 2935 4890 770 1492 412 2793 1955 2935 4890 770 1624 544 2869 U6 2440 2790 5 230 900 1768 688 2946 2440 2790 5230 900 1924 844 3022 2440 2790 5230 900 2094 1014 3096 2440 2790 5 230 2280 1200 3165 2440 2790 5230 2480 1400 3232 2440 2790 5230 2700 1620 3294 2440 2790 5 230 2939 1859 3350 2440 2790 5230 3200 2120 3400 2440 2790 5230 - 3200 - - 2120 3400 .P -- Heightening of dam D -- Generation of 28 Plant = Total-1080 x O * C q r ? ~ ~ Y ~ c ! ~ ~ * ~ ~ a ! C q o ! * ~ ~ Y ~ k c ! r r ! ~ k ~ * F ~ Y m ~ a a ~ ( ~ b r a ~ ~ ) ~ W c ~ r b d d ~ ~ r ~ r ) a ~ a ~ ~ ~ ~ , m * Q, O O V W b O , N W b O N W b O ) N I O C O r V b O O b O O b r r O O , d a J C ) a 3 V Q , V ) ~ ~ ~ - ~ ~ ~ ~ ~ m o m m m v v v m m m ( ~ ( ~ ( ~ ~ ~ ~ a r r r r r J I CI ! TABLE 18 HIGH CAPANDA / LOW SCENARIO -- ALT I . B ANNEX 2 GWh Pag. 18/39 FIRM ENERGY Demand Peak CAM CAP GT TOTAL CAM CAP GT TOTAL TOTAL D CAPANDA TOTAL D CAPANDA 727 790 790 135 135 765 790 790 135 138.6 807 790 17 807 135 146.3 854 1080 1080 135 154.8 854 904 1080 1080 135 163.8 904 959 1080 1080 135 173.8 959 1016 1080 1080 135 184.1 1016 1073 1080 1080 135 185 1073 1147 1080 U1 1195 2275 135 260 520 627 1220 1080 1195 2275 135 260 537 683 1302 1080 1195 2275 135 260 573 729 1367 1080 1195 2275 135 260 588 779 1479 1080 1195 2275 135 260 621 858 1577 1080 1195 2275 135 260 663 914 1683 1080 U2 2170 3250 135 385 570 1113 1791 1080 2170 3250 135 385 574 1217 1888 1080 2170 3250 135 385 577 1311 1985 1080 2170 3250 135 385 58 1 1404 2087 1080 2170 3250 135 385 585 1502 2186 1080 2170 3250 135 385 589 1597 2292 1080 2170 3250 135 385 592 1700 2403 1080 U3 2350 3430 135 500 596 1807 2520 1080 2350 3430 135 500 600 1920 2644 1080 2350 3430 135 500 655 1989 2775 1080 2350 3430 135 500 715 2060 2914 1080 2350 3430 135 500 78 1 2133 3060 1080 2350 3430 135 500 853 2207 3216 1080 U4 2450 3530 135 580 931 2285 3380 1080 2450 3530 135 580 1017 2363 3554 t 1385 2492 3877 195 640 1110 30 2444 3738 1385 2492 3877 195 640 1212 132 2526 3934 U5 1955 2935 4890 325 770 1323 243 261 1 4141 1955 2935 4890 325 770 1445 365 2696 4360 1955 2935 4890 325 770 1578 498 2782 4593 1955 2935 4890 325 770 1723 643 2870 4839 U6 2440 2790 5230 455 900 1882 802 2957 9 -- Heightening of dam D -- Generation of 2a Plant = Total-1080 br" ' 1 I r ! , TABLE 19 HIGH CAPANDA I LOW SCENARIO -- ALT II . B GWh MW GENERATION (GWh) Pag. 19/39. FIRM ENERGY FIRM CAPACITY WITHOUT INTERCONNECTION WITH INTERCONNECTION Year Demand Peak CAMBAMBE JCAMBAMBE I CAM CAP GT TOTAL CAM CAP GT TOTAL .- TOTAL D CAPANDA TOTAL D CAPANDA - . -- 1990 727 790 790 131.8 135 135 1991 765 790 790 138.6 135 3.6 138.6 1992 807 1 790 17 807 146.3 135 11.3 146.3 1993 854 1080 U1U2 - 1080 154.8 135 19.8 154.8 1994 904 , 1080 1080 163.8 135 28.8 163.8 1995 959 1080 1080 173.8 135 38.8 173.8 1996 1016 1080 1080 184.1 135 49.1 184.1 1997 1073 1080 1080 194.5 135 50.0 185 1998 1147 1080 1195 2275 207.9 135 125 260 1999 1220 1080 1195 2275 221.1 135 125 260 2000 1302 1080 1195 2275 236.0 135 125 260 200 1 1367 1080 1195 2275 247.7 135 125 260 2002 1479 1080 1195 2275 268.0 135 125 260 2003 1577 1080 1195 2275 285.0 135 125 260 2004 1683 1080 2170 3250 305.0 135 250 385 2005 1791 1080 2170 3250 324.6 135 250 385 2006 1888 1080 2170 3250 342.2 135 250 385 2007 1985 1080 2170 3250 359.7 135 250 385 2008 2087 1080 2170 3250 378.2 135 250 385 2009 2186 1080 2170 3250 396.2 135 250 385 2010 2292 1080 2170 3250 415.0 135 250 385 201 1 2403 1080 U3 2350 3430 435.5 135 365 500 2012 2520 1080 2350 3430 456.7 135 365 500 2013 2644 1080 2350 3430 479.2 135 365 500 2014 2775 1080 2350 3430 502.9 135 365 500 2015 2914 1080 2350 3430 528.1 135 365 500 2016 3060 1080 2350 3430 554.6 135 365 500 1 2017 3216 1080 U4 2450 3530 582.8 135 445 580 2018 3380 1080 2450 3530 612.6 135 445 580 2019 3554 't 1385 2492 3877 644.1 195 445 640 2020 3738 1385 2492 3877 677.4 195 445 640 2021 3934 U5 1955 2935 4890 713.0 325 445 770 1 2022 4141 1955 2935 4890 750.5 325 445 770 2023 2024 4360 4593 1955 1955 2935 2935 4890 4890 790.2 832.4 325 445 325 445 770 770 1 2025 1 4839 U6 2440 2790 5230 877.0 455 445 900 1 t -- Heightening of dam D -- Generation of 2a Plant = Total-1080 L O - N O d U , W b a D ~ O - N O d U -, N W ~ b ~ o W ~ ~ ~ W~ ~ O ~ ~ ~ U ~ ~) ~O ~ - ~ N ~ ON ~ N U N ~ N m m m m m m m m m m m o o o o o o o o o o a m m m m m m m m m m o o o o o o o o o o o o o o o o o o o o o o o o o o > .-.-.-.-.-7.-.-.--NNNNNNNNNNNNNNNNNNNNNNNNNN ANNEX 2 Pag. 22/39 CAMBAMBE - COST ESTIMATES AND INVESTMENT PLANS w ( P r i c e system r e f e r e n c e : end o f 1989) A - HEIGHTENING OF THE DAM A t p r i c e s of 1984 t h i s work was e s t i m a t e d a t 111.9 m i l l i o n s of USD (Study BEP, JUL/86). Assuming an annual average growth o f t h e c i v i l construction c o s t s o f about l o % , a t p r i c e s o f t h e end o f 1989 t h a t c o s t w i l l reach an ammount o f 180.0 m i l l i o n s o f USD ( M . U S D ) . For a t i m e o f c o n s t r u c t i o n of 5 years the corresponding investment p l a n i s : YEAR 1 2 3 4 5 . M USD 27.0 45.0 45.0 45.0 18.0 B - NEW POWER STATION (1ST PHASE:Units U5 and U6 o f 130 MW each one) A t p r i c e s o f 1984 t h i s work, t h e n foreseen f o r t h e installation o f two u n i t s of 110 MW each one, was e s t i m a t e d as f o l l o w s (Study B.E.P., JUL/86): C i v i l construction ... 79.45 M.USD Equipments ........... 142.91 M.USD However t h e c o s t o f t h e g e n e r a t i n g u n i t s seems t o be v e r y overenhanced (47% above t h e corresponding t o t h e Capanda u n i t s ) ; so, a f t e r t h e necessary a d j u s t i n g t h a t c o s t was f i x e d a t 107.05 M.USD. Assuming an annual average growth o f t h e equipment c o s t s o f about 7% and t a k i n g i n account t h e i n c r e a s e o f t h e u n i t a r y c a p a c i t y from 110 MW t o 130 MW, a t p r i c e s o f t h e end o f 1989 t h e c o s t o f t h i s new power s t a t i o n w i l l reach t h e f o l l o w i n g values: C i v i l construction .... 151.0 M.USD Equipment ............. 177.0 M.USD Total ............. 328.0 M.USD ANNEX 2 Pdg. 23/39 For a time of construction of 5 years and the initial installation of only one unit, it results the following investment plan (in M.USD): YEAR 1 2 3 4 5 6 Civil const. 22..0 38.0 38.0 38.0 15.0 Equ i pment 42.5 42.5 G5 REMARK: As the inlet works of the new power station must be built d u r i n g the heightening of the dam, the coresponding equipments, whose cost is estimated at 7 . 0 M.USD, will have to be installed until the end of that heightening. So, a possible total investment plan is of the following type (in M.USD). YEAR 1 2 3 4 5 6 7 8 ? ? ? - - Heightening C.C. 27.0 45.0 45.0 45.0 18.0 EQ . 3.5 3.5 New Power C.C. 22.0 38.0 38.0 38.0 15.0 Station EQ . 42.5 42.5 G5 42.5 42.5 G6 PNNtA 2 Pg. 24/39 TABLE 22 ALT. I. A 1 INVESTMENT 0&M GENERAIION (GWh) GENERAIION (GWh) Without interconnection With interconnection I YEARS (millions USD) (millions USD) I CAPANDA CAMBAMBE CAPANDA CAMBAMBE CAPANDA CAMBAMBE 111.o 181.0 100.8 119.2 160.2 156.2 2.0 39.0 8.7 59.4 54.2 2.0 U1 3.7 40.4 3.7 36.8 3.7 U2 5.5 5.5 5.5 5.5 5.5 5.5 7.2 7.2 7.2 7.2 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 8.9 TOTAL 1299.1 508.0 ANNEX 2 Pg. 25/39 INVESTMENT O&M GENERATION YEARS (millions USD) (millions USD) (GWh) r 1 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 201 0 201 1 2012 201 3 201 4 201 5 201 6 201 7 201 8 201 9 2020 2021 2022 2023 2024 2025 ... TOTAL ANNEX 2 Pg. 26/39 TABLE 24 / ALT. Ill. A 1 INVESTMENT 0 8 M YEARS (millions USD) (rnillioris USD) I CAPANDA CAMBAMBE CAPANDA CAMBAMBE 91 .O' 111.o 181.o 119.2 160.1 113.5 8.7 62.0 53.4 1 I U1 36.8 1 U2 TOTAL 1304.5 508.0 ANNEX 2 Pg. 27/39 TABLE 25 I ALT. I. B I) INVESTMENT 0 8 M GENERATION YEARS millions USD (millions USD) (GWh) 1985 1986 1987 1988 1989 1990 91.01 111.0 181.0 100.81 119.2 ' i i I CAPANDA CAMBAMBE CAPANDA / CAMBAMBE 1991 1992 39.0 1993 8.7 1994 1995 1996 59.4 1997 54.2, 1998 1999 MOO 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 201 1 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 TOTAL 1299.2 508.0 ANNEX 2 Pg. 28/39 TABLE 26 INVESTMENT O&M GENERATION YEARS (millions USD) (millions USD) (GWh) CAPANDA CAMBAMBE CAPANDA CAMBAMBE CAPANDA I CAMBAMBE 91 .o 111.0 181.O 100.8 119.2 160.2 p2.4 135.8 I Ul,U2 24.81 TOTAL ANNEX 2 Pg. 29/39 INVESTMENT O&M GENERATION (millions USD) I YEARS (millions USD) CAPANDA 1 CAMBAMBE CAPANDA 1I CAMBAMBE GzSykGE 1 TOTAL 1304.5 508.0 ANNEX 2 Pg. 30139 TABLE 28 ALT. I. A HIGH SCENARIO - Long Range Marginal Costs 1 DISCOUNT RATE OBS: -Values discounted to January . 1990 -Unit 1 of CAPANDA in January. 1996 -Heightening of CAMBAMBE dam in January. 2011 10.0% 12.0% 15.0% -Reference prices: end of 1989 Discounted costs (millions USD) lnvestment O&M Total CAPANDA Total discounted generation (GWh) Without interconnection With lnterconnection Levelized generating cost (USDIkWh) Without interconnection With lnterconnection Discounted costs (millions USD) lnvestment O&M Total CAMBAMBE Total discounted generation (GWh) Without interconnection With interconnection Levelized generating cost (USDIkWh) Without lnterconnection With lnterconnection Discounted costs (millions USD) lnvestment O&M Total CAPANDA + Total discounted generation (GWh) CAMBAMBE Without lnterconnection With lnterconnection Levelized generating cost (USDIkWh) Without lnterconnection With lnterconnection ANNEX 2 Pg. 31/39 ALT. II. A HIGH SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 DISCOUNTRATE I -Units 1 and 2 of CAPANDA in Jan. 93 and Jul. 93 -Heightening of CAMBAMBE dam in January. 201 1 -Reference prices: end of 1989 Discounted costs (millions USD) Investment 0& M CAPANDA Total I /I Total discounted generation (GWh) I Levelized generating cost (USDIkWh) Discounted costs (millions USD) Investment O&M CAMBAMBE Total I 1I Total discounted generation (GWh) I Levelized generating cost (USDIkWh) Discounted costs (millions USD) Investment O&M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) I I Levelized generating cost (USDikWh) ANNEX 2 Pg.32/39 TABLE 30 ALT. Ill. A - HIGH SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 DISCOUNT RATE -Unit 1 of CAPANDA in January .I996 -Heightening of CAPANDA dam in January. 2002 -Heightening of CAMBAMBE dam in January. 2 011 10.0% 12.0% 15.0% -Reference prices: end of 1989 Discounted costs (millions USD) Investment 1208.1 1217.4 1241.9 0&M 41.2 30.9 21.2 CAPANDA Total 1249.3 1248.3 1263.1 Total discounted generation (GWh) 9567.8 6676.0 4143 Levelized generating cost (USDIkWh) 0.1306 0.1870 0.3049 Discounted costs (millions USD) Investment 71.8 49.9 29.4 O&M 5.8 3.3 1.5 CAMBAMBE Total 77.6 53.2 30.9 Total discounted generation (GWh) 1297.1 692.5 282.9 Levelized generating cost (USDIkWh) 0.0598 0.0768 0.1092 Discounted costs (millions USD) Investment 1279.9 1267.3 1271.3 O&M 47.0 34.2 22.7 CAPANDA Total 1326.9 1301.5 1294.0 + CAMBAMBE Total discounted generation (GWh) 10864.9 7368.5 4425.9 Levelized generating cost (USDIkWh) 0.1221 0.1766 0.2924 ANNEX 2 Pg. 33/39 TABLE 31 ALT. I. B - LOW SCENARIO - Long Range Marginal Costs DISCOUNT RATE OBS: -Values discounted to January . 1990 -Unit 1 of CAPANDA in January. 1998 -Heightening of CAMBAMBE dam in January .2019 -Reference prices: end of 1989 Discounted costs (millions USD) lnvestment O&M CAPANDA Total I Total discounted generation (GWh) Levelized generating cost (USDlkWh) 1 0.1810 / 0.2691 1 0.4616 1 Discounted costs (millions USD) lnvestment 0& M CAMBAMBE Total Total discounted generation (GWh) Levelized generating cost (USDIkWh) Discounted costs (millions USD) lnvestment O&M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) Levelized generating cost (USDIkWh) ANNEX 2 Pg. 34/39 TABLE 32 ALT. II. B - LOW SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 1 DISCOUNT RATE -Units 1 and 2 of CAPANDA in Jan. 93 and Jul. 93 -Heightening of CAMBAMBE dam in January .2019 -Reference prices: end of 1989 Discounted costs (millions USD) lnvestment O&M CAPANDA Total Total discounted generation (GWh) I Levelized generating cost (USDIkWh) Discounted costs (millions USD) lnvestment CAMBAMBE 1 O&M Total 1 I Total discounted generation (GWh) ~ 1 Levelized generating cost (USDIkWh) Discounted costs (millions USD) Investment 1286.9 1293.0 1318.6 O&M 34.7 25.1 16.6 CAPANDA Total 1321.6 1318.1 1335.2 + CAMBAMBE Total discounted generation (GWh) 7398.0 4858.2 2805.4 I I Levelized generating cost (USDIkWh) 0.2713 1 ANNEX 2 Pg. 35/39 ALT. Ill. B LOW SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 DISCOUNT RATE -Unit 1 of CAPANDA in January . 1998 -Heightening of CAPANDA dam in January .2007 -Heightening of CAMBAMBE dam in January. 2019 10.0% 12.0% 15.0% -Reference prices: end 1989 Discounted costs (millions USD) Investment O&M CAPANDA Total I I Total discounted generation (GWh) I 6214.41 4123.6 / 2386.1 I I 1 I Levelized generating cost (USDIkWh) 1 0.1920 1 0.2899 1 0.5095! I -- I Discounted costs (millions USD) Investment 33.5 20.2 9.6 0& M 2.5 1.3 CAMBAMBE Total 36.0 21.5 10.1 I 1 Total discounted generation (GWh) 1 649.6 1 302.6 1 101.2 1 Levelized generating cost (USDIkWh) ( 0.0554 / 0.071 1 1 Discounted costs (millions USD) Investment 0& M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) 1 6864.01 4426.2) Levelized generating cost (USDIkWh) 0.1 791 0.2750 0.4929 - mTJD( 2 Pag. 36/39 ANGOLA @ Natioml Copital 0 P r a i m Capitals o SelacdTas - Railroads ---- pi,, 4 Airports . L Porn Praince hmdc&8 --- Intcrnotioml Uaudario '.-......-Dm -U...rI..~.IW m1 . 1 - . - . -a . - h -. ..- .PO. .- -L.-O)lolcl-m .n*ln-Wa.l rn.w I - . -. .a - w e . ., 0 ----- 0 0 U 220kV Wans"lission line for the interconnection of the Northern System to the Central and Southern systems L ANGOLA L TABLE 34 L C . E G . S . A N D S.EC3.S. ( expanalone wlth Interconnection ) L Y C. E G. S. 19911 1996 20a5 2MO 2CnS COMPONENT DEMAND 255Gwh 286 &I1 838 Qwll 895 Gwh 1198 Gwli HMRO : C ACOMBO 1- 1- LOMAUM 1- 1-1 BlOPlO pazq THERMAL : WITHOUT A) 21.Wwh (1.89 M USD) 1 1 7 , W h (11.12MUSD) 41 4.I?Gwh (11.43 h4 USD) INTERCONNECTION B) 0.0 MW 5 1 , W (3.27 M USD) 140.8hmv (8.87 M USD) WITH A) O.Wwh 1 3 , m h (I .27 M USD) 80.OGwli (8.01 M USD) - INTERCONNECTION B) 0.0 nlw 0.OMw 50.1 Mw (3.53 h 4 USD) S. E G. S. 1096 1898 10W m 0 2M B COMPONENT DEMAND 115 a w h 124 a w h 237 Owh 317 Qwh 405 Qwh HWAO : GOVE loMW_(R)_1 1- MATALA p6zmq THERMAL : WITHOUT A) O.Wh W , W h (10.03 M USD) 125,211 (13.44 h4 USD) a) - INTERCONNECTION 0.0 Mw 27.Oh (1.70M USD) 47.sMw (3 .02M USD) WITH A) O.Oawh 0,Wwh 17.6(3wh (1 .a9 M USU) INTERCONNECTION 8) 0.0 Mw 0 . m ~ Z~2.i'Mw (2.06 M USD) A] 1.89-0,O-1,89 . 11.I2-1.27-9.85 41.43-8.01 -33.12 C. E G. S. 8) + 3 374.0--3 a -j - - INTERCONNECTION 1A9 13.1 2 38,7(3 VALUE A) 0.0 10.03-0.0-1 0,03 13,44-1.89- 11,55 ( M USD) 8. E G , S, 6) A + 1.70-0,O =1.7Q --;~.W-Q 0.0 11.73 12.61 TOTAL 1.89+0,0-I,@ 13.111+11.73 - 0.99+ -23.86 38.76+12.51 - 3.61 -47.60 Inorease of NORTHERN SYSTEM's fuel oosb due to the lnteroonneotion I [ lntegrdon of Ihs scheme In the sydem,wlth the lndloated power output (R) Only for regulallng purposae A) Ganerdon at the average of the hydrological reglmsa and respeolhm fuel ooatn Emergency capeclly necessery In new gas turblnea durlng crlllcal perlod (dec.1958)and corresponding annual charge (discount rafe: 10% ) ANGOLA I TABLE 35 I C. E G. S. A N D S. E G. S. ( expanalona with Interoonneodon ) C. E Q, S. 1995 1998 2005 2MO 201 5 COMPONENT DEMAND 2WGwh 286 Gwh 638 Gwh 895 Gwh 11BBGwh HYC)RO : CACOMBO 1- F M ~ LOMAUM 1-L pzT&iil BlOPlO THERMAL : WITHOUT A) 21.OGwh (1 .@aM USD) 117.9Gwh (11.2 M USD) I 414.Xwh (41.43 M USD) INTERCONNECTION B) . 0.0 hhv 61 .eMw (3.79 M U SD) 14o.aMw (1028 M USD) WlTH A) O.OGwh 13.ffiwh (1.27 M USD) - 80.oGwh (8.m hi USD) INTERCONNECTION B) 0.0 Mw o* . 66.1 Mw (4.1 o M USD) 1995 19M M05 2MO 201 5 COMPONENT DEMAND 116Gwh 124 Gwh 237 Gwh 317 Gwh 406 Gwh ~ R : O GOM MATALA THERMAL : WITHOUT A) 0.ffiwh 84.OGwh (10.03 M USD) 125.Xwh (13.44 M USD) INTERCONNECTION B) 0.0 Mw 27.OMw (.97 M USD) I 47.9Mw (3.50M USD) WlTH A) O.OGwh o.ffiwh 17.6Gwh (1-89 M USD) INTERCONNECTION 8) 0.0 Mw 0,OMw 32.7Mw (2.38 M US01 A) 1.88-0.0=1.89 11.1 2-1.27=8.85 ~33.42 41-438.01 B) A P m2!kmk&m INTERCONNECTION 1.89 13.64 39.60 VALUE A) 0.0 1O.(XfO.O=lO.03 13.44-1.W= 11.65 ( M USD) 8) a + 1.87-0.0 - -1.97 j 3.5 - 0-3.39-1 .I1 Increase of NORTHERN SYSTEM'Sfuel varlable costs due to the lt~torconnectlon 1- Integration of the scheme In the system ,with the lndlcoled power output (R) Only for regulating purposes A) Generation at the average of the hydrological reglmes and respecUve fuel costa 6) Emergency capaclty necessary In new gas turblnes durlng crltlcal perlod (dec. 58) and corresponding annual charge ( discount rate: 12%) ANNEX 7A Pag. 1/3 The b a s i c p l a n n i n g problem f o r an e l e c t r i c u t i l i t y i s t o design a system so t h a t i t can be b u i l t and operated i n t h e most economical manner and p r o v i d e a s a t i s f a c t o r y q u a l i t y o f s e r v i c e . The o p t i m a l expansion o f t h e e l e c t r i c power system i s a m u l t i d i m e n s i o n a l s e q u e n t i a l d e c i s i o n problem and i t r e q u i r e s t h e a p p l i c a t i o n o f s e v e r a l models i n t e g r a t e d i n a g l o b a l methodology. The two g r e a t groups o f models a r e c l a s s i f i e d , according to t h e i r main purposes, as f o l l o w i n g : . "dynamic" models, aiming a t t h e o p t i m a l expansion o f the power system over t i m e , thus j o i n i n g investment and management d e c i s i o n s ; . "static" models whose purpose i s t h e o p t i m a l management o f t h e system o p e r a t i o n once t h e investment d e c i s i o n s , and t h e r e f o r e t h e system composition, a r e known. The VALORAGUA model, developed by E l e c t r i c i d a d e de P o r t u g a l , EDP, i s i n c l u d e d i n . t h e second group above r e f e r r e d t o . It - s t u d i e s t h e o p t i m a l management o f a predetermined power system configuration. c I n an e l e c t r i c power system w i t h s i g n i f i c a n t h y d r o e l e c t r i c r e g u l a t i o n c a p a b i l i t i e s , t h e h y d r o e l e c t r i c s t o r a g e can be use t o a t t e n u a t e t h e seasonal f l u t u a t i o n s of power demand o r o f water i n f l o w s by t r a n s f e r r i n g water from p e r i o d s w i t h h i g h i n f l o w s t o p e r i o d s o f lower i n f l o w s , t a k i n g i n t o account t h e expected power demand over those p e r i o d s . So a d e c i s i o n o f water r e l e a s e o r I water r e t e n t i o n a t a g i v e n p e r i o d w i 11 have almost s u r e l y an i n s t a n t a n e o u s consequence i n t h e r e d u c t i o n o r increase o f t h e operation costs, but a l s o i t w i l l influence the operation i n the f u t u r e by t h e s i d e o f a m o d i f i c a t i o n o f water a v a i l a b l e i n t h e reservoirs i n the future. The VALORAGUA model a l l o w s an i n t e g r a t e d management o f a r f i x e d hydrothermal power c o n f i g u r a t i o n whose o b j e c t i v e i s t o f i n d t h e most economical o p e r a t i o n p o l i c y , t a k i n g i n t o account t h e p h y s i c a l c o n s t r a i n t s and t h e random c o n d i t i o n s o f t h e system operation. The model c o n s i d e r s t h e p o s s i b i l i t y o f t r a n s f e r water f r o m p e r i o d s o f h i g h i n f l o w s t o p e r i o d s o f lower i n f l o w s , introducing t h e i d e a o f v a l u e o f water (VALOR da AGUA) r e s u l t i n g from t h e ANNEX 7 A Pag. 2 / 3 a r b i t r a t i o n between immediate g a i n ( a s s o c i a t e d t o an economy on f u e l ) and e x p e c t a t i o n o f a f u t u r e g a i n . To a c h i e v e t h i s goal t h e o p t i m a l management o f t h e system r e q u i r e s t h e s o l u t i o n o f two problems: . medium-term management o f t h e w a t e r r e s e r v o i r s I t d e t e r m i n e s t h e so c a l l e d c o s t - t o - g o f u n c t i o n s , r e l a t e d t o the value o f s t o r e d water, u s i n g a s t o c h a s t i c dynamic programming a l g o r i t h m ; t h e h y d r o e l e c t r i c subsystem i s f u l l y aggregated i n t o an e q u i v a l e n t one. . S h o r t - t e r m management o f h y d r o t h e r m a l system F o r each p e r i o d i t d e t e r m i n e s t h e f i n a l s t o r a g e o f each r e s e r v o i r and t h e system g e n e r a t i o n s c h e d u l e i n o r d e r t o m i n i m i z e t h e sum o f o p e r a t i o n c o s t s i n t h a t p e r i o d w i t h t h e expected v a l u e o f f u t u r e o p e r a t i o n c o s t s . T h i s i s a non l i n e a r o p t i m i z a t i o n problem, s o l v e d by an a p p r o p r i a t e d non l i n e a r programming a l g o r i t h m . The hydrothermal electric system is completely d i saggregated. The model a n a l y s e s a p e r i o d o f one y e a r f o r w h i c h t h e c o m p o s i t i o n o f t h e g e n e r a t i o n system i s w e l l d e f i n e d . T h e y e a r i s C d i v i d e d i n t w e l v e p e r i o d s b e i n g t h e month t h e u n i t o f t i m e c o n s i d e r e d f o r management purposes. The model s i m u l a t e s t h e o p t i m i z e d o p e r a t i o n o f t h e system u s i n g a h y d r o l o g i c a l t i m e series of i n f l o w s a t each h y d r o power s t a t i o n . The VALORAGUA model a l l o w s an i n t e g r a t e d management o f a h y d r o - t h e r m a l e l e c t r i c power system, making t h e l i n k between t h e w a t e r management and t h e thermal o p e r a t i o n , t a k i n g i n t o account n o t o n l y p h y s i c a l and technical c h a r a c t e r i s t i c s o f t h e system b u t a l s o economic I p a r a m e t e r s and v a r i a b l e s , mainly a c a r e f u l c a l c u l a t i o n of economic d u a l v a r i a b l e s : m a r g i n a l g e n e r a t i o n c o s t and m a r g i n a l value o f water. T h i s d e t a i l e d i n f o r m a t i o n on t h e economic b e h a v i o u r o f t h e system e n a b l e s t w o i m p o r t a n t a p p l i c a t i o n s of t h e model: economic e v a l u a t i o n o f h y d r o e l e c t r i c schemes and o p t i m i z a t i o n o f some if r i t s technical characteristics. O t h e r t y p e o f a p p l i c a t i o n i s t h e s t u d i e s on a s i m p l i f i e d generation-transmission network e n a b l i n g t h e d e l i m i t a t i o n o f i n t e r e s t i n g areas f o r f u t u r e power p l a n t s l o c a t i o n s and t h e e v e n t u a l need o f e x t e n s i o n of t h e t r a n s m i s s i o n network. ANNEX 2 A Pag. 3/3 The country is divided into several interconnected areas, each of them with its own generation plants and load demands. Those areas are symbolized by nodes linked by transmission lines, which are defined by means of loss coefficients depending on their physical characteristics and by power flow bounds. The model determines the optimal generation dispatches and both electrical power and monetary flows between nodes. Power flows from nodes with lower generation costs to nodes with higher ones. So when marginal costs of those nodes are closer, less power flows between electrical nodes occurs. ANNEX 3 Pqg. 1/4 T A B L E 1 DEMAND FORECAST a) HIGH SCENARIO SYSTEMS NORTHERN CENTRAL SOUTHERN Load Factor : 0.63 Lcad Factor : 0.624 Load Factor : 0.57 Enerpy Growth Capacity Energy Growth Capacity Energy Grow-th Capacity YEAR rate rate rate 1987 (GWhl (%I (MW) (GWhl * I 0a.s (%I (MW 20 . . [GWh) 62 I%) IMW) 12 1986 * 112 3.0 21) 63 1 .O 13 19aB 695 i26 120 7.0 22 64 3.D 13l 1990 730 5.0 132 133 I 1.a 24 ~a 5.0 14 1931 766 5.0 139 149 12.0 27 73 0.0 15 1992 620 7.0 149 1 E3 13.0 31 80 10.0 16 1993 886 8.0 160 163 15.0 35 DO 12.0 18 1994 874 1 0.0 177 222 15.0 41 1 04 15.0 21 1995 ID91 12.0 188 255 15.0 47 115 1 1 .O 23 1996 1222 12.0 221 288 12.0 52 1 24 8.0 25 1997 1388 12.0 24B 320 12.0 59 134 8.0 27 1996 1518 11.0 275 359 12.0 66 145 8.0 29 1999 1656 Q.0 330 358 71.0 73 156 B.0 31 2000 1788 6.0 32C 434 9 .O 79 169 B.0 34 200 1 1814 7.0 347 463 8.0 68 161 7.0 36 2002 2048 7.0 371 507 8.0 63 194 7.0 3D 2003 2191 7.0 397 547 8.0 207 7.0 41 2004 2345 7.0 425 591 8.0 1 o !0 l 222 7.0 44 2005 2509 7.0 455 633 8.0 117 237 7.0 47 2006 2658 6.0 482 663 7.0 1 25 251 6.0 50 2007 261D 6.0 51 1 731 7.0 134 268 6.0 53 2a08 2988 6.0 541 762 7.0 143 262 6.0 56 2008 3187 6.0 574 836 7.0 1 53 299 6.0 60 2010 3357 6.0 606 895 7.0 164 317 6.0 63 231 1 3525 5.0 639 949 6.0 174 333 5.0 87 201 2 3701 5.0 671 1006 6.0 1 64 350 5.0 70 2013 3886 5.0 704 1066 8.0 185 367 5.0 73 2014 4081 5.0 739 1130 6.0 207 386 5.0 77 2015 4285 5.0 776 1188 6.0 219 405 5.0 81 i - -- - -- - -- a) At generation level * Value actually verfled 1 TABLE 2 C.EG.S. of A N G O L A 7 EXPANSION WITHOUT INTERCONNECTION I DEMAND 255 200 3M 350 300 434 469 507 54 7 591 uo 1 Averege LOMAUM 181 200 260 292 322 348 372 377 382 378 BlOPlO 62 65 50 58 62 70 72 75 70 74 78 Tlmrmal U n l t ~ 12 2l 10 11 13 16 25 55 25 18 73 GACOMBO - - - - - 0 0 0 60 62 42 Dry Year I LOMAUM 153 194 180 180 190 348 370 289 378 384 352 1 I DEMAND 47 82 69 68 73 78 100 108 117 I GACOMBO - - - - - 0 0 0 7.8 4.8 2.0 I BlOPlO 5.0 8.3 6.0 6.0 6.0 10.8 9.9 6.5 10.8 7.9 5.0 I COMPONENTS THERMAL I Huambo(GT)10.0hAW1 Caoombo 24 MW(1) 12 MW(u) Lomaum 65 MW(I) HYDRO I I); ; ; ; ; ; Bloplo Bloplo MW(a) 14.1 MW(Q 10.8 MW(a) R - Only for regulating purpoeee - (I) lnetded (a) - nvnilnblo TABLE 3 t s.EG,S, of A N Q O L A EXPANSION WITHOUT INTERCONNECTION 1995 1 19s 1997 1 W8 1998 MOO 2001 ~ 2 0 0 2 [ 2 0 0 3 [ M M I 205 rI DEMAND 115 124 13 4 145 158 Is9 181 184 207 m 237 1 W f QOVE R R R R 53 57 63 69 90 97 105 Awraga 1 MATALA 115 124 134 143 103 112 117 122 117 125 128 1 Thermal Unltn 0 0 0 2 0 0 1 2.6 0 0 4 GOVE R R A A (18 63 74 78 85 93 05 (1 958) Thermal Unlte 0 0 0 11 0 0 2 10 0 0 12 I DEMAND 23.0 25.0 27.0 29.0 31. O 34.0 38.0 38.0 41 .O 44.0 47.0 1 Thermal Units 0 0 0 9.2 0 0 . 40 7.0 0 0 1.3 1994 1W5 19M 1997 1998 1999 MOO !XI01 2002 203 2004 2a05 R - Only for regulating purpoeee (l) - lnelallod (a) - available ANNEX 3 Pag.414 INVESTMENTS - (M. U S D ) WITH WITHOUT WITH WlTHOLlT INTERCONNECTION INTERCONNECTION INTERCONNECTION INTERCONNECTION CACOMBO GAS TURBINE! 15.0 22.5 5.5 -- m.0 12.1 GOVE 30.0 6.6 2 5 MW 2GsD 30.0 30 MW 20.0 22.5 Plant 30 MW Dam 16.0 16.0 16.0 2G.O Plant 24 MW Plant 45 MW Study horlzon Study horizon INVESTIMENT COSTS DISCOUNTED TO THE BEGINNING OF 1895 D~scounr r A rate 1CA6 55.7 1 @,g 10.3 33.9 12% 44.2 162.3 7.4 37,l 15% 31.6 152.1 4.6 33.4 ANNEX 2 Pg. 25/39 I I YEARS INVESTMENT (millions USD) 0 8 M (millions USD) GENERATION (GWh) TOTAL ANNEX 2 Pg. 26/39 TABLE 24 1 INVESTMENT O&M GENERATION I &~ YEARS (millions USD) (millions USD) I TOTAL 1304.5 508.0 ANNEX 2 Pg. 27/39 1 INVESTMENT I GENERATION YEARS CAPANDA CAMBAMBE CAPANDA I CAMBAMBE TOTAL 1299.2 508.0 ANNEX 2 Pg. 28/39 TABLE 26 1 INVESTMENT I GENERATION 1 YEARS (millions USD) CAPANDA 1 CAMBAMBE 1 TOTAL ANNEX 2 Pg. 29/39 TABLE 27 ALT. Ill. B ) I INVESTMENT O&M GENERATION YEARS (millions USD) (millions USD) (GWh) CAPANDA / CAMBAMBE CAPANDA CAMBAMBE CAPANDA CAMBAMBE :: 1 1985 91.O I 1986 1987 1988 1989 119.2 I 1990 160.1 1991 113.5 1992 26.5 1993 8.7 2.0 1994 2.0 1995 2.0 1996 2.0 1997 2.0 1998 U1 3.7 436 1999 3.7 464 2000 40.4 3.7 495 2001 36.8 I 3.7 520 2002 U2 5.5 810 2003 5.5 864 2004 5.5 922 2005 31.7 5.5 98 1 2006 29.0 1 5.5 1034 2007 (1 5.5 1404 2008 5.5 1502 2009 39.2 5.5 1597 2010 35.8 5.5 1700 2011 U3 7.2 1807 2012 7.2 1920 2013 7.2 1989 2014 27.0 7.2 2060 2015 34.6 45 .O 7.2 2133 2016 31.6 67.0 7.2 2207 2017 U4 86.5 8.9 2285 2018 59.5 8.9 2363 2019 f 80.5 8.9 2.0 2444 30 2020 57.5 8.9 2.0 2526 132 2021 U5 8.9 3.7 2611 243 2022 8.9 3.7 2696 365 2023 42.5 8.9 3.7 2782 498 2024 42.5 8.9 3.7 2870 643 2025 U6 8.9 5.5 2957 802 2026 8.9 5.5 3027 976 2027 8.9 5.5 3098 1166 2028 8.9 5.5 3171 1374 2029 8.9 5.5 3245 1601 2030 8.9 5.5 3322 1849 2031 8.9 5.5 3400 2120 ... ... ... ... ... TOTAL 1304.5 508.0 ANNEX 2 Pg. 30139 TABLE 28 ALT. I. A HIGH SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 -Unit 1 of CAPANDA in January . 1996 DISCOUNT RATE - I -Heightening of CAMBAMBE dam in January .2011 Discounted costs (millions USD) lnvestment 0&M Total CAPANDA Total discounted generation (GWh) Without interconnection With lnterconnection Levelized generating cost (USDIkWh) Without interconnection With lnterconnection Discounted costs (millions USD) lnvestment O&M Total CAMBAMBE Total discounted generation (GWh) Without interconnection With interconnection Levelized generating cost (USDlkWh) Without lnterconnection With lnterconnection p p - - Discounted costs (millions USD) lnvestment O&M Total CAPANDA + Total discounted generation (GWh) CAMBAMBE Without lnterconnection With lnterconnection Levelized generating cost (USDIkWh) Without lnterconnection With lnterconnection ANNEX 2 Pg. 31/39 TABLE 29 ALT. II. A 7 HIGH SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 / DISCOUNT RATE I -Units 1 and 2 of CAPANDA in Jan. 93 and Jul. 93 -Heightening of CAMBAMBE dam in January .2011 -Reference prices: end of 1989 Discounted costs (millions USD) Investment O&M CAPANDA Total I / Total discounted generation (GWh) I I Levelized generating cost (USDIkWh) Discounted costs (millions USD) lnvestment O&M CAMBAMBE Total 1 I Total discounted generation (GWh) I Levelized generating cost (USDIkWh) I 0.05981 0.0768 1 1 0.1092 Discounted costs (millions USD) Investment O&M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) Levelized generating cost (USDIkWh) ANNEX 2 Pg. 32/39 TABLE 30 - ALT. Ill. A HIGH SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 DISCOUNT RATE -Unit 1 of CAPANDA in January. 1996 -Heightening of CAPANDA dam in January .2002 -Heightening of CAMBAMBE dam in January .2011 10.0% 12.0% 15.0% -Reference prices: end of 1989 Discounted costs (millions USD) Investment O&M CAPANDA Total I ' Total discounted generation (GWh) I 9567-8 1 4143 I I Levelized generating cost (USDIkWh) 0.1306 I 0.18701 Discounted costs (millions USD) Investment 71.8 49.9 29.4 O&M 5.8 3.3 1.5 Total 77.6 53.2 30.9 I Total discounted generation (GWh) 1 1297.1 1 692.5 1 282.9 1 Levelized generating cost (USDlkWh) I -I0.0598 -I 0.0768 -I 0.1092 Discounted costs (millions USD) Investment O&M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) I 1 Levelized generating cost (USDIkWh) 0.1221 ANNEX 2 Pg. 33/39 ALT. I. 6 LOW SCENARIO - Long Range Marginal Costs DISCOUNT RATE OBS: -Values discounted to January . 1990 -Unit 1 of CAPANDA in January. 1998 -Heightening of CAMBAMBE dam in January .2019 10.0% 12.0% 15.0% -Reference prices: end of 1989 I Discounted costs (millions USD) lnvestment O&M CAPANDA Total I Total discounted generation (GWh) 1 6748.4 1 4555.6 / 2704.2 1 Levelized generating cost (USDIkWh) 0.1810 0.2691 0.4616 1 Discounted costs (millions USD) lnvestment O&M CAMBAMBE Total I I Total discounted generation (GWh) Levelized generating cost (USDIkWh) Discounted costs (millions USD) lnvestment O&M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) Levelized generating cost (USDIkWh) ANNEX 2 Pg. 34/39 TABLE 32 ALT. II. B 1 LOW SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 1 DISCOUNT RATE -Units 1 and 2 of CAPANDA in Jan. 93 and Jul. 93 -Heightening of CAMBAMBE dam in January .2019 10.0% 12.0% 15.0% -Reference prices: end of 1989 Discounted costs (millions USD) lnvestment 0 8 M CAPANDA Total I Total discounted generation (GWh) 1 6748.41 4555.61 2704.2! 1 1 Levelized generating cost (USDIkWh) ) 0.1905 / 0.2846 I 0.4900 -I I 1 Discounted costs (millions USD) lnvestment 08 M Total I / Total discounted generation (GWh) I Levelized generating cost (USDIkWh) 1 0.0554 ( -I 0.071 1 -1 0.0998 Discounted costs (millions USD) lnvestment 08M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) Levelized generating cost (USDikWh) ANNEX 2 Pg. 35/39 -- - ALT. Ill. B - LOW SCENARIO - Long Range Marginal Costs OBS: -Values discounted to January . 1990 -Unit 1 of CAPANDA in January .I998 -Heightening of CAPANDA dam in January. 2007 DISCOUNT RATE I -Heightening of CAMBAMBE dam in January. 201 9 -Reference prices: end 1989 Discounted costs (millions USD) Investment 0& M CAPANDA Total I I Total discounted generation (GWh) 1 6214.4 1 4123.6 / 2386.1 1 I Levelized generating cost (USDIkWh) / 0.1920 1 -0.2899 I 0.50951 I Discounted costs (millions USD) Investment 33.5 20.2 9.6 0 8 M 2.5 1.3 0.5 CAMBAMBE Total 36.0 21.5 10.1 Total discounted generation (GWh) 649.6 302.6 101.2 Levelized generating cost (USDFWh) 0.0554 0.0711 0.0998 Discounted costs (millions USD) Investment O&M CAPANDA Total + CAMBAMBE Total discounted generation (GWh) Levelized generating cost (USDIkWh) - ANNM2 Pag. 36/39 ANGOLA Nolioml Copitol b Prorince Copitola o SclardTama - k i n Rmda Roilmads -- . i^- ia r- ----- 220kV Transmission l i n e f o r the i n t e r c o n n e c t i o n of the Northern System to t h e C e n t r a l and Southern Systems s ' 1 - 4 - '3. E22E P d . *n 3 3 3 3 ISEE 23 gg d 32 I 2 5 r r C + F 9 .- a s ZS ~ ~ ZS uj cj c i w l a - W 6 ? m e 2 z z Q 0 0 ..(3 9 0 3 ..+z u 3 k Zj' 2 t- Y z z O a38 g s z%E~D -3 5 r55 - Lu z - I ANGOLA L TABLE 35 L C . E G. S. A N D S.E G. S. (expanslorn with Interoonnsotlon) - C. E a, S. 109s 1 m 2005 m o 201 5 COMPONENT DEMAND 2MGwh me Gwh Gwh 895 Gwh IlmGwh HYDRO : CACOMBO . p-iiIMWI LOMAUM psiwl BlOPlO pmimq THERMAL : WITHOUT A) ~ t .oGwh l (1.a3 M USD) 117.9Gwh ( I 1.1 2 M USD) 414.2Gwh (41.43 M USD) INTERCONNECTION ! B . 0.0 Mw M .QMw (3.79 M USD) I#.& ( 1 0 a M USD) WITH A) o.oGwh 13.BGwh (1.27 M USD) ao.o(;wh (8.01 M USD) INTERCONNECTION B) om ~w 0.oMw 68.1Mw (4.10hlUSD) 8. E 0 . 8 . 1995 1998 2005 m 0 2015 COMPONENT DEMAND ll6Gwh 124 Gwh 237 Gwh 317 Gwh 406 Gwh HYDRO : GOM la!E@il 1- MATALA piimq THEIWAL : WITHOUT A) 0.oGwh m.oGwh (10.03 M USD) 125.Xwh (1944M USD) INTERCONNECTION B) 0.0 Mw 27.OMw fl,97MUSD) 47.9Mw (3.50 M USD) WITH A) 0.oGwh 0.oGwh 17.6Gwh (1.88 M USD) INTERCONNECTION 8) 0.0 h4w 0,OMw 32.7Mw (2.39 M USD) C. EQ. S. A) 8) A 1.8W.0=1.89 1.89 - 11-12-1.27=0.85 3 3-79-Olo3.79 13.64 41 -43-8.M =33.42 -10 =I618 39.60 INTERCONNECTION VALUE A) 0.0 10.03-0.0=10.03 13.44-1.88~11.55 ( M USD) s. E G. S. B) + i.a7-0.0 - -1 .m + 3.50 -3.39-1 .I 1 0,O 19.00 12.86 TOTAL 1.89+0.0=1.89 13.64+12.W - 0.9St =24.65 39.60+12.68 - 3.61 *=48.65 t lncreaee or NORTHERN SYSTEM'e fuel varlable costs due to the llltorconnectlon lntegratlon or the scheme In the eyetern ,wlth the indlcoled power output (R) Only tor regulallng purposes A) Generation at the average of the hydrologlcalreglrnes and respective fuel costs B) Emergency capaclty necessary In new gas turblnes during critical period (dec. 58) and corresponding annual charge ( discount rate: 12% ) ANQOLA T A B L E 36 h C. E 0. 6, A N D 5, E Q. 8. ( exyellelone wlth Interconllectlon ) L I C. E G.S. 1995 1898 MOS 2OlO 2M6 COMPONENT DEMAND BGwh 206 awh 630M 895 Qwh 11Qaawh HYDRO : CACOMBO 1- 1- LOMAUM 1- 1- BlOPlO pcmiiq THERMAL : WITHOUT A) 21. W h (1.89 M UBD) 117.MWh (ll,l2MUSD) 414 . m h (41.43 M USD) IMERGONNECTION 8) 0.0 Mw 51.gMw (4,@ M USD) 1.M.BMw (12.53 M USD) WITH A) 0.OQwh 1 3 . W h (1.27 M U8D) 80,OQwh (8,01 M U3D) INTERCONNECTION 8) 0.0 h4w 0.OMw 56,lMw ( 4 , M FA USD) S. E G. S. 1W6 1998 aaW 2010 2016 COMPONENT DEMAND 115 Gwh 124 (iwh 237 C3Gwh 317 Gwh 405 Gwh HYDRO : OOVE [MW(R)) 1- MATALA 1- THERMAL : WITHOUT A] 0,Oawh W,OGwh (10,W M USD) 125.2G~h (13.44 M USD) INTERCONNECTION a) 0.0 Mw 2 7 . a ~(2.40M USD) 47.8Mw (4.28 M USD) WITH A) O.OGwh O.Oawh 17.tiGwh (1$89 M USD) INTERCONNECTION B) 0.0 Mw 0.oMw 32.7Mw (2.91 M USDj A) 1.880,O-1.89 11.2-1 -27-9.85 I 41,434.M -33.42 c. E (3.S. 8) A - + 4 M . D -4 6 9 RJTERCONNEGTlON 1,89 14.47 40,W VALUE A) 0.0 10.030,O-10.03 13.44-1 .89- 11-55 ( M USD) B, E a. 8. 8) a j-2.404.0-?& + 4.282.81 =1.35 0.0 12.43 12.80 TOTAL 1,89+0.0=1.89 14.47+1243 - 0.99 -25.91 - 10.9$+12.90 3.61c-50.25 z Inorease of NORTHERN SYSTEM'S fuel costs due to the lnteroonneotfon 1-1 Integration of the scheme In the syatern.wlth the lndloated power output (R) Onty for regulallng purpoaea A) Generation at the awrage of the hydrological reglmes and rsspsothm fuel ooata 8) Emergency capacity necessary In new gae turblnes durlng critlcal perlod (dec, 1958) and correspondlng annual charge (discount rate: 15%) Pag. 1/3 The VALORAGUA model The basic planning problem for an electric utility is to design a system so that it can be built and operated in the most economical manner and provide a satisfactory quality of service. The optimal expansion of the electric power system is a multidimensional sequential decision problem and it requires the application of several models integrated in a global methodology. The two great groups of models are classified, according to their main purposes, as following: . "dynamic" models, aiming at the optimal expansion of the power system over time, thus joining investment and management decisions; . "static" models whose purpose is the optimal management of the system operation once the investment decisions, and therefore the system composition, are known. The VALORAGUA model, developed by Electricidade de Portugal, EDP, is included in.the second group above referred 'to. It - studies the optimal management of a predetermined power system configuration. L In an electric power system with significant hydroelectric regulation capabilities, the hydroelectric storage can be use to attenuate the seasonal flutuations of power demand or of water inflows by transferring water from periods with high inflows to periods of lower inflows, taking into account the expected power - demand over those periods. So a decision of water release or water retention at a given period will have almost surely an instantaneous consequence in the reduction or increase of the operation costs, but also it will influence the operation in the future by the side of a modification of water available in the reservoirs in the future. The VALORAGUA model allows an integrated management of a r fixed hydrothermal power configuration whose objective is to find the most economical operation policy, taking into account the physical constraints and the random conditions of the system operation. The model considers the possibility of transfer water from periods of h i g h inflows to periods of lower inflows, introducing the idea of value of water ( V A L O R da AGUA) resulting from the PNNFX 2 A Pag. 2/3 arbitration between immediate gain (associated to an economy on fuel) and expectation of a future gain. To achieve this goal the optimal management of the system requires the solution of two problems: . medium-term management of the water reservoirs It determines the so called cost-to-go functions, related to the value of stored water, using a stochastic dynamic programming algorithm; the hydroelectric subsystem is fully aggregated into an equivalent one. . Short-term management of hydro thermal system For each period it determines the final storage of each reservoir and the system generation schedule in order to minimize the sum of operation costs in that period with the expected value of future operation costs. This is a non linear optimization problem, solved by an appropriated non linear programming algorithm. The hydrothermal electric system is completely disaggregated. The model analyses a period of one year for which the composition of the generation system is well defined.The year is c divided in twelve periods being the month the unit of time considered for management purposes. The model simulates the optimized operation of the system using a hydrological time series of inflows at each hydro power station. The VALORAGUA model allows an integrated management of a hydro-thermal electric power system, making the link between the water management and the thermal operation, taking into account not only physical and technical characteristics of the system but also economic m parameters and variables, mainly a careful calculation of economic dual variables: marginal generation cost and marginal value of water. This detailed information on the economic behaviour of the system enables two important applications of the model: economic evaluation o f hydroelectric schemes and optimization of some if r its technical characteristics. Other type of application is the studies on a simplified generation-transmission network enabling the delimitation of interesting areas for future power plants locations and the eventual need of extension of the transmission network. ANNEX 2A Pag. 3/3 The c o u n t r y i s d i v i d e d i n t o s e v e r a l i n t e r c o n n e c t e d areas, each o f them w i t h i t s own g e n e r a t i o n p l a n t s and l o a d demands. Those areas a r e symbolized by nodes l i n k e d by t r a n s m i s s i o n l i n e s , which a r e d e f i n e d by means o f l o s s c o e f f i c i e n t s depending on t h e i r p h y s i c a l c h a r a c t e r i s t i c s and by power f l o w bounds. The model d e t e r m i n e s t h e o p t i m a l g e n e r a t i o n d i s p a t c h e s and b o t h e l e c t r i c a l power and monetary f l o w s between nodes. Power f l o w s f r o m nodes w i t h lower g e n e r a t i o n c o s t s t o nodes w i t h h i g h e r ones. So when m a r g i n a l c o s t s o f t h o s e nodes a r e c l o s e r , l e s s power f l o w s between e l e c t r i c a l nodes o c c u r s . ANNEX 3 Pag. l/4 TABLE I OEMAND FORECAST a) HIGH S C E N A R I O SYSTEMS NORTHERN CENTRAL SOUTHERN Load Factor : 0.83 Lcad Factor : 0.824 Load Factor : 0.57 Energy Growth Capacity Energy Growth Capacity Energy Growth Capacity YEAR rate rate rate (%I (%I (MW I%) IMW GWhl (MW) (GWhl 4 +. (Gm) 1987 108.5 21 C 62 12 1986 4 112 3.0 20 63 1 .O 13 1 :gaa 69s 126 120 7.0 22 64 3.0 12i1 1990 730 5.0 132 133 11.0 24 8a 5.0 14 1931 766 5.D 138 149 12.0 27 73 8.0 15 1992 820 7.0 149 189 13.0 31 80 10.0 16 1993 886 8.D 160 1G3 15.0 35 QO 12.0 18 1994 974 10.0 177 222 15.0 41 104 15.0 21 1995 1091 12.0 188 255 15.0 47 115 11.0 23 1996 7 222 12.0 221 2B5 12.0 52 124 8.0 25 1997 1388 12.0 248 320 72.0 59 134 8.0 27 1998 1518 11.0 275 359 12.0 66 145 6.0 29 1999 1656 8.0 330 3% 71.0 73 156 B.0 31 2000 1788 8.0 324 434 8.0 79 169 6.0 34 2001 1814 7.D 347 463 8.0 68 161 7.0 36 2002 2048 7.0 371 507 8.0 83 194 7.0 39 2003 2791 7.0 397 547 8.O 1DO 207 7.0 41 2004 2345 7.0 425 591 8.0 108 222 7.0 44 2005 2509 7.0 455 633 8.0 117 237 7.D 47 2006 2658 6.0 482 683 7.0 125 251 6.D 50 2007 261 B 6.0 511 731 7.0 134 268 6.0 53 2008 6.0 54 1 762 7.0 143 262 6.0 56 2009 3187 6.0 574 836 7.0 153 299 6.0 60 2010 3357 6.0 606 895 7.0 164 317 6.0 63 231 1 3525 5.0 639 949 6.O 174 333 5.0 67 201 2 3701 5.0 671 10W 6.0 1 64 350 5.0 70 2013 3886 5.0 704 1066 8.0 1 95 367 5.0 73 201 4 4081 5.0 739 1130 6.0 207 386 5.0 77 2015 4285 5.0 776 1188 6.0 219 405 5.0 81 a) At generation level +. Value actually verified TABLE 2 I 1 C.EG.S. of A N G O L A - EXPANSION WITHOUT INTERCONNECTION 1894 1095 109R 1997 1WO 1008 2000 2001 2002 2003 2004 2009 1 DEMAND 255 200 320 350 300 434 489 507 54 7 591 wo Average TIwrmel Unlte 12 21 10 11 13 16 25 55 25 48 73 CACOMBO - - - - - 0 0 0 60 62 42 Dry Year (1858) 1 LObAAuhA 1W 184 I90 190 190 348 370 293 378 384 352 Dec. 1 LOMAUM BlOPlO Thermal Unlta lgM , THERMAL IW I HU~~~~(GT)IO.OM Caoombo 24 MW(I) 12 MW(u) Lomaum 45 MW(I) Lomaum 65 MW(4 30 MW (a) 55 MW(a) Bloplo 14.4 MWQ 10.8 MW(aL R -Only for regulating purpose8 - (I) Installed - (a) nvnilnblo 1 TABLE 4 i ANNEX 3 Pag.4/4 INVESTMENTS I WITH WITHOUT WITH WITHOUT INTERCONNECTION INTERCONNECTION INTERCONNECTION INTERCONNECTION CACOMBO GAS TURBINES 15.0 22.5 5.5 . 3.0 12.1 GOVE 30.0 6.6 2 5 IbW 2G.D 30.0 30 MW 20.0 22.5 Plant a MW Dam 16.0 16.0 16.0 CACOMBO Ptant 24 MW 15.0 22.5 33.0 Study horizon Study horizon m.0 30.0 22.5 Dam GOVE 20.0 23.0 20.0 Plant 24hiW Plant MW Study horizon Study horizon INVESTIMENT COSTS DISCOUNTED TO THE BEGINNING OF 1995 D~scount r rate 10% 55.7 1m,Q 16.3 33.8 1 2% 44.2 162.3 7.4 37.1 1% 31 -6 152.1 4.6 33.4