A study on three different hydropower operation rules by monthly and daily time steps

Operation simulation models are developed for monthly and daily time steps for computing the hydroelectric energy and its financial benefits in an economic life by three different operation policies: steady-rate, three-shift and pumped-storage rules. The pump is operated during the night and consumes low-cost energy. The resulting computer programs, three on monthly and three on daily steps, are applied to the Yamula dam – which is a fairly large dam generating energy, located in the Inland Anatolia region of Turkey – over a period of 35 years using the gauged daily stream flows and daily pan evaporations. The results indicate that the pumped storage is more profitable than the other two rules aside from the intangible benefits of regulating the within-day fluctuations of demand for electrical energy. Another result is that both the average annual energy and the financial benefits given by the three rules computed by the monthly time steps are about 1−2% greater than those given by the daily time steps. This study is the first one comparing all these three operation schemes quantitatively in a realistic way both in monthly and daily time steps.