A New Backup Automatic Switch Scheme Adaptable to Photovoltaic Power Integration

With the integration of photovoltaic power stations into power grids, the traditional strategy of the backup automatic switch is affected. When a grid fault occurs, due to the existence of photovoltaic power sources, the busbar voltage at the fault point cannot meet the "no voltage" criterion, and the traditional strategy cannot operate correctly. Currently, most engineering solutions sacrifice photovoltaic power generation to ensure that the traditional scheme can meet the normal operation conditions. This paper analyzes in detail the voltage and frequency variation laws at the grid-connected point after the main power supply fails due to faults. Based on this, aiming at the common "source greater than load" scenario in engineering, a new backup automatic switch scheme based on crowbar resistors is proposed: input corresponding numbers of crowbar resistor groups according to the degree of power mismatch between source and load at the grid-connected point, realizing backup automatic switch without cutting off photovoltaics. Finally, MATLAB/Simulink simulation verifies the effectiveness and feasibility of the new backup automatic switch scheme.