Research on the fault characteristics and protection of photovoltaic grid-connected distribution network

PSCAD is used to construct the fault simulation model of photovoltaic grid-connected system, and the influence of photovoltaic grid-connected on electrical quantity before and after normal operation is analyzed theoretically and simulated. The influence of fault type, fault location, transition resistance and other factors on fault characteristics in distribution network with photovoltaic grid-connected is simulated and analyzed. The influence of fault type, fault location and transition resistance on photovoltaic grid-connected distance protection is analyzed theoretically, and the related distance protection is simulated and analyzed. Studies have shown that the location of photovoltaic grid-connected aggravates various faults in the power grid, such as the influence of fault location, fault type, transition resistance, etc.on electrical quantities, and have a significant impact on distance protection. When the photovoltaic grid is closer to the fault location, the greater the impact on the electrical quantity of the power grid; among various fault types, when the photovoltaic grid is connected to a fixed position, the influence of singlephase grounding fault on the electrical quantity of the system is greater, when the transition resistance increases,the photovoltaic module will promote the voltage increase after grid connection; when the photovoltaic grid is connected to a fixed position, the closer the fault position is to the photovoltaic grid-connected position, the easier the distance protection is to make mistakes.