Kidatu power plant was built in two phases under the name of Great Ruaha Power Project that was carried out in 1970’s for phase one and 1980’s for phase two. Phase I was completed in 1975 that comprised of construction of an earth-rock fill dam, an initial capacity of 2 x 50MW, and 220kv transmission line to Dar es Salaam via Morogoro. Phase II completed 1980 which involved additional of 2 x 50MW, and construction of a bigger storage dam at Mtera with capacity of 3,200 Mill m3.
The plant has undergone two major rehabilitation works. Rehabilitation phase I covered repair turbine one and two, replacement of excitation equipment and repair of a damaged generator unit one. The works were executed from 1993 to 1994. Estimate cost of the project was 25 Million SEK. Financiers were SIDA and TANESCO. The rehabilitation commence from 1999 to 2003. Major works were computerizing the control and protection system, repair on turbines, replacement of runners on units 1and 2, generators and water ways. The project was financed by SIDA, NORAD and TANESCO. Estimated cost was about 12 Million US$.
The power station generates an average of about 0.8 billion units yearly for the past five years, however for the good hydrological year the station can generate over 1 billion units.
Kidatu power plant contributes about 36% of the total hydro installed capacity.
Operation and Maintenance
Operation of generating units is controlled by a semi automated computerized system called interactive graphic supervisory system (IGSS32).
The new control system is divided into three main parts namely station control unit, local control unit and data control and supervision system. The station control unit controls the whole station while the local control units control the individual plants like machines, dam and 220/33kV substation. All the local control units are connected to the data control and supervision system (SCADA) via station control unit. The unit control units are connected through profibus. There is a provision of starting the machines from the local control unit if the SCADA or station control unit fails. Also there is a provision of remote start/stop of machines from the Ubungo grid control centre.
Initially maintenance was carried out using the bar chart maintenance system until the introduction of computerized maintenance management system called Job Tech, supplied by Norconsult Norway during the rehabilitation phase II. The bar chart system was done manually, very slow, no proper reliable records keeping and difficult in follow up. The Job Tech computerized system helps to plan work tasks and resources utilization, ensures that no planned work tasks are overlooked, builds up valuable maintenance information and history, secure a cost effective operation of plant and obtain optimal maintenance thus prevent unexpected breakdowns. However the system has failed due to technical problem of the computer server. The process to revive the system is in progress.
Phase II rehabilitation project could not cover all necessary repairs of plant and equipment therefore it is planned to have Phase III rehabilitation project. The project that will cover the following:
Modification of the 220kV system because the substation is the major link of interconnections e.g. Kihansi, Mtera, and new power stations to be built in a near future.
Repair and refurbishment of auxiliary equipments.
Generator no.2 realignment of up-bracket.
|Crest length (m)||350|
|Type of dam||Earth rock fill|
|Concrete volume (m3)||40,000|
|Fill volume (m3)||800,000|
|Spillway capacity (m3/s)||6,000|
|Live storage (Mill.m3)||125|
|Catchment’s area (km2)||10|
|Kidatu Power station|| |
|Total generating capacity (MW)||200|
|No. of units||4|
|Length of headrace tunnel (km)||9.6|
|Length of tailrace tunnel (km)||1.0|
|Total rock excavation volume (Mill.m3)||1.0|
|Discharge capacity through turbines (m3/s)||140|
Project cost and financing
Construction cost for phase I was about 102 Million US$ financed by International Bank for Reconstruction and Development, the Swedish International Development Authority, the Canadian International Development agency and the Government of Tanzania. Main contractors and consultantThe supervision for project layout and kidatu dam and power station was done by the Swedish Consulting Group (SWECO) Stockholm. Other contractors were as follows:
|Civil works||KICON and C G JENSEN|
|Transmission line and Substation||COMSTOCK (QUEBEC) Ltd.|
|Gates and Penstock steel lining||INGRA-METALNA, and HITACHI|
|Turbines and Cranes||INGRA-LITOSTROJ and J M VOITH|
|Generators||INGRA-RADE KONCAR |
|Main transformers||Ferranti-Packard and ASEA|
|Switch gear and control equipment||COGELEX and BBC|
|22kV Cables||ASEA CABLE|
|Cooling water pipes||Balfour Kilpatrick International Ltd|