Risk control of hydropower-photovoltaic multi-energy complementary scheduling based on energy storage allocation

The complementary scheduling of hydropower with wind and photovoltaic (PV) power is an effective way to promote new energy consumption. However, previous studies have disregarded the operational risks of hydropower plants due to their physical constraints when complementing new energy sources. This study proposes a risk control method for a hybrid hydro-PV power system by adding electrochemistry energy storage (EES). A "day ahead–intraday–real-time" three-layer nested model is developed to guide the joint operation of the hydro-PV-EES hybrid system. The complementary flexibility of hydropower and EES is quantified and utilized to minimize unfavorable operating conditions of hydropower units when regulating PV forecast deviations. A case study of China's Longyangxia hydro-PV complementary project shows that after EES is connected to the system: (1) the total power generation of the system is improved 3.04%, and no power curtailment or shortage occurs; (2) the number of startups and shutdowns, and crossing the vibration zone of hydropower units are reduced by 12.87% and 12.17%, thereby improving the safety and operational stability of the hydropower plant; (3) the regulation flexibility supply of the complementary system is considerably improved; and (4) EES achieves flexible and safe control itself, with over 90% of the scheduling periods being in a healthy SOC range.