Ecological optimal scheduling of hydropower stations on the upper Yellow River considering renewable energy accommodation

To mitigate the impacts of renewable energy accommodation on the river flow regime and ecological integrity in scheduling of hydropower stations on the upper Yellow River, a multi-energy complementary system ecological scheduling model was established with the objectives of minimizing variations in river flow regime, maximizing power generation of hydropower stations, and ensuring the highest stability of generation output. A multi-objective evolutionary algorithm was employed to explore the balance among the generation output of the multi-energy complementary system, renewable energy accommodation, and ecosystem protection of rivers. The results indicate a clear competitive relationship between power generation of hydropower stations and river ecosystem protection objectives. The larger the fluctuation in generation output of the multi-energy complementary system, the greater the power generation of hydropower stations and the larger the variation in river flow regime. Moreover, the larger the inflow volume, the smaller the impacts of ecological scheduling of hydropower stations on river flow regime, and the impacts are mainly concentrated on the indicators, including the numbers of annual occurrences of high/low flow pulses and the average increase/decrease rate of flow. In the scheduling results with maximum power generation in dry years, the indicators of the number of annual occurrence of low flow pulses and average decrease rate of flow have the greatest changes.