Expansion Planning of Renewable Energy Power System Considering Flexibility and Economy

The large-scale access to renewable energy such as wind power and photovoltaics brings great uncertainty in power system planning and operation. In order to enhance the ability of high-proportion renewable energy grid to respond to uncertain events and ensure the safe and economic operation, it is necessary to improve the flexibility of the power system. First, based on the perspective of line transmission capacity and safe operation, the flexibility index of the transmission line was defined. Next, considering the economic operation strategy of the system, a multi-objective transmission line planning model based on flexibility and economy was proposed to optimize the flexibility index, investment cost, operating cost, and renewable energy consumption. After that, the NSGAII optimization algorithm was used to solve the model. Finally, the improved Garver-6 and IEEE RTS-24 node systems were taken as examples to analyze the effectiveness of the proposed model. The results show that the planning scheme can improve the transmission capacity of power grids, reduce the probability of renewable energy abandonment, and improve the flexibility and economy of power grid operation.