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...Akosombo Hydro Plant
........... ...Retrofit Project
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Akosombo Hydro Power Plant Retrofit

   

Since the first unit at Akosombo Generating Station was commissioned and the production of electrical power on a commercial basis started in 1965, the Akosombo Generating Station has provided Ghana, and its neighbouring countries, with a reliable source of electrical energy.

During this period of operation, the electrical and mechanical plant in the powerhouse has undergone a regular maintenance program, but in 1988, after 23 years of continuous operation, it became evident to VRA, that a major retrofit would have to be carried out, to ensure the safe and efficient operation of the station for at least another 25 years of operation. Therefore, in 1988 a study was initiated and completed, to determine the extent of the retrofit work required, and in 1989 the Akosombo Generation Station Retrofit Project (AGSRP) was implemented.

The initial objective of the AGSRP, was to return the turbine/generator units to an "as new" condition replacing those parts which were beyond repair, to replace or renovate the auxiliary equipment, and to improve the powerhouse amenities and services. This would ensure the station would operate safely in the future, with a minimum of outages and inconvenience to VRA's customers.

The project progressed with the retrofit of the first unit, Unit 4, completed in September 1993. However, during the retrofit of Unit 4, it became evident that with state-of-the-art technology, the turbine runners could




be replaced, and modifications made to other turbine parts, to provide a unit with a higher efficiency and increased rated output.  Therefore in October 1993, all future retrofit work was suspended, to enable VRA to fully study and assess the implications of replacing the turbine runners, instead of rehabilitating the existing ones. The outcome of the study was to replace the runners, financing was established, and a Contract was awarded for the new turbine runners and other modifications to the turbines.  In October 1999, Unit 3 was taken out of service and over a 9-month period the turbine and generator were retrofitted, the old runners being replaced with a new design, higher efficiency runner.  The retrofit was completed and Unit 3 was returned to service in August 2000.  Tests were then carried out by an independent company, which showed that the performance of the retrofitted unit exceeded the guaranteed performance given by the Contractor.

The maximum output of the unit at the lake level when tested, has increased by 37%, when compared against the output of the original designed turbine at the same lake level. This represents an improved utilization of the water resources provided by Lake Volta, and is a major financial benefit to VRA.

The retrofit of the remaining five units at Akosombo Generating Station, Units 3,2,6,5 and 1 were completed in that order over a five-year period and officially handed over to VRA on March 3, 2006. At the full completion of the Retrofit Project, the generation capacity has increased significantly by 108MW, from 912MW to 1020MW.





 


Major Customers

Electricity Co. of Ghana
Anglogold Ashanti
Volta Aluminium Co. Ltd.