Fault Ride-Through of N-1 Preplan of Photovoltaic and Energy Storage Systems

In order to ensure that there will be no chain reaction after the failure of a single element of photovoltaic and energy storage system (PV-ESS), and the power supply to critical loads can still be maintained, N-1 security region (SR) analysis of PV-ESS is carried out in this paper. Based on the SR, fault ride- through (FRT) can be realized by removing non-critical loads from unsafe working points. Firstly, the control and power responses of PV-ESS are analyzed. Secondly, the concept of SR of energy storage system with large photovoltaic (LPV-ES3R) is proposed. Then, the SR analysis of 110kV/20kV medium-voltage distribution network proposed by International Large Power Grid Conference is carried out to obtain the change process of the SR with large photovoltaic (LPV) system under different PV output conditions. Finally, the safety optimization ability of MMC-HVDC is analyzed after it is connected to AC system, the concept of safe distance is introduced, and the load shedding strategy based on improved particle swarm optimization (PSO) is adopted to realize FRT for unsafe operating points. The correctness of the proposed scheme is verified by simulation.