Economic operation of a wind-solar-hydro complementary system considering risks of output shortage, power curtailment and spilled water

Integrated operation of hydropower, wind and photovoltaic (PV) power, which exploits the regulation flexibility of hydropower to complement the uncertainty of wind and PV power outputs, is a promising way to enhance resource utilization efficiency. However, the short-term economic operation of the wind-solar-hydro complementary system (WSHCS) has risks such as output shortage, power curtailment and spilled water. To address this issue, we propose three risk indicators to quantify them and then optimize the WSHCS. To begin with, the uncertainties of WSHCS are described, and varied forecast scenarios are produced by the copula method. Then, the three risks of WSHCS, which are quantified based on the output errors of wind-solar and regulation ability of hydropower station, are used as objective functions of the optimization model. Finally, a two-layer nested approach is used to optimize online units of hydropower station for minimizing the risks of WSHCS and water consumption of hydropower station. The Guandi wind-solar-hydro hybrid power plant on China's Yalong River is selected as a case study. Results from the case study show that the output shortage of WSHCS mainly occurs in the two time periods: 1) when the upper limit of regulation ability of the hydropower station is small, and 2) when the output of wind or PV power is large. The probability of output shortage during WSHCS operation is reduced from 100% to 0%, and the probability of spilled water can be reduced by 46.7%similar to 73.9%, without power curtailment. Thus, this study provides the technical support for safe and economic operation of renewable energy.