Construction of pumped storage power stations among cascade reservoirs to support the high-quality power supply of the hydro-wind-photovoltaic power generation system

Multi-energy complementary technology has become one of the core elements to promote the structural transformation of global energy and cope with climate change. Faced with the rapid growth of wind power and photovoltaic, the uncertainty of its power generation will increase further, and it is urgent to explore more types of flexible regulation power sources to compensate for them. The construction of pumped storage power stations among cascade reservoirs is a feasible way to expand the flexible resources of the multi-energy complementary clean energy base. However, this way makes the hydraulic and electrical connections of the upper and lower reservoirs more complicated, which brings more uncertainty to the power generation. Hence, to support the high-quality power supply, this research explores the complementary characteristics of the clean energy base building different types of pumped storage power stations, and recognizes the efficient operation intervals of the giant cascade reservoir. First, a multi-dimensional uncertainty evaluation system is proposed to elaborate on the typical output scenarios of wind power and photovoltaic in more detail. Next, based on different utilization principles of wind power and photovoltaic, the multi-energy complementary operation models of the hydropower-wind-PV hybrid system, the hydropower-wind-PV hybrid system including pump stations, and the hydropower-wind-PV hybrid system including reversible hydro units are established. Further, a multi-dimensional scenarios random combination method is applied to investigate the response relationship between the operation parameters of the key reservoir and the operation indicators of the clean energy base. Finally, these above methods have been practiced in the clean energy base in the upper Yellow River basin. The main results of the research are as follows: (1) when the power output of wind-PV plants is high, the absorption rates of wind power and photovoltaic increase by 36% and 12% respectively, in hydropower-wind-PV hybrid systems with reversible hydro units and with pump stations, compared to the hydropower-wind-PV hybrid system; (2) when the power output of wind-PV plants is high, the load loss rates of the transmission channel decrease by 28.57% and 14.28% respectively, in hydropower-wind-PV hybrid systems with reversible hydro units and with pump stations, compared to the hydropower-wind-PV hybrid system; (3) for the hydropower-wind-PV hybrid system including reversible hydro units, the comprehensive utilization flow of the key reservoir respectively maintain 500-800 m³/s and 1000-1200 m³/s in the max scenario and min scenario of wind power and photovoltaic, which is beneficial to the efficient absorption of new energy and high-quality power transmission; (4) for the hydropower-wind-PV hybrid system including pump stations, the comprehensive utilization flow of the key reservoir should respectively keep 500-750 m³/s and 950-1100 m³/s in the max scenario and min scenario of wind power and photovoltaic.