Xiaojin county in Sichuan province is high in the northeast and low in the southwest

and is rich in light and water resource

which is conducive to the construction of a cascaded hydropower-photovoltaic-pumped hydro storage (HP-PV-PHS) complementary power plant. However

the HP-PV-PHS capacity ratio greatly affects the complementary benefits. Because PV output fluctuates frequently and the time scale is small

the multi-scenario cascaded HP-PV-PHS capacity allocation and optimized operation under the minutes time scale is proposed. From the view of improving the economic benefits and delivery stability of the complementary system

firstly

a bi-level mathematical model for capacity allocation and optimized operation of a cascaded HP-PV-PHS with minimal investment cost and minimal power fluctuation in delivery is established. Secondly

the method and execution steps of the bi-level programming model based on particle swarm optimization and sequential quadratic programming algorithm (PSO-SQP) are described in detail. Finally

the accuracy and reasonability of the bi-level programming model is analyzed in multiple scenarios. The case study reveals that 5 MW PHS can make the cascaded HP-PV-PHS complementary system have a maximum investment benefit ratio and mitigate the power fluctuation on tie-line by up to 11.7%.