Unconventional Risks and Prevention and Control Strategies for Photovoltaic Distribution Grids Containing High Penetration Rates

With the vision of “double carbon”, China has begun to vigorously develop a clean, low-carbon, safe and efficient energy system, and build a new power system with new energy as the main body. With the high penetration of photovoltaic power supply into the distribution network, the coordination between traditional risk and protection can no longer meet the technical requirements of the new distribution network relay protection. Therefore, this paper focuses on the three aspects of the non-conventional risk of PV power supply, its analysis method and the distribution network protection scheme adapted to the access of PV power supply. Firstly, the general structure of PV power supply is introduced, and the working principle of inverter and grid-connected control strategy under normal state are analyzed, and then from the perspective of distribution grid, the method of analyzing the extraordinary risk of distribution grid is proposed, and the symmetrical and asymmetrical fault characteristics of distribution grid and the problems when PV power supply is connected to distribution grid are analyzed. In addition, for the method proposed in this paper, the equivalent model of PV power access to the distribution network is used as the basis to study the fault characteristics of PV power access to the distribution network, analyze the impact of PV power access to the existing current protection of the distribution network, and propose to classify the distribution network into three regions according to the location of PV power access, and then put forward the preventive and control strategies respectively. Finally, the feasibility of the protection scheme proposed in this chapter is verified by simulation.