Multi-objective optimal operation of pumped-hydro-solar hybrid system considering effective load carrying capability using improved NBI method

Hybrid renewable energy system (HRES) is an effective approach to aggregate multiple renewables efficiently. This paper focuses on the optimal operation of a hybrid system consisting of pumped hydro storage, cascade hydropower station, run-of-river hydropower station and photovoltaic plant. Various elements and contradictory aims like reliability and economy makes the operation of HRES complex. With this regard, a multi-objective optimization model is proposed to maximize both effective load carrying capability (ELCC) and economic revenue of the hybrid system. An improved normal boundary intersection (NBI) method is proposed to solve the multi-objective problem and obtain the Pareto surface. Moreover, to ensure the optimality of the results, big-M method, binary expansion method integrated with linearization transformation techniques are employed to linearize the model. Results are presented and discussed in the case study, which verify the feasibility of the model, demonstrate the effectiveness of the improved NBI method and illustrate the significance of involving ELCC into HRES operation.