Abstract
This research paper aims at evaluating the reliability performance of two units each from Shiroro and Kainji hydro electric power stations of Nigeria. The result of this study is intends to provide the basis for planning generation expansion of hydro electric power stations in Nigeria. Herein reliability evaluation based on the Frequency and Duration (F & D) approach is adopted. A set of reliability parameters which quantify generating unit reliability, are computed for each unit using the annual outage durations for the period of the study (2005-2009). The system failure probability (unavailability), frequency of system failure (FF), and the mean duration of system failure (TF) for each unit were obtained and fully discussed. The reliability of the individual unit was also computed for the period of study. The study generally shows that the generating units at Kainji Hydro Power Stations have not been adequately maintained, leading to frequent and delayed forced outage. This indicates unreliable performance of the individual units and the entire stations as compared with Shiroro Hydro Power Station.