Research on theoretical calculation methods of photovoltaic power short-circuit current and influencing factors of its fault characteristics

Abstract

With the substantial increase in the capacity of grid-connected photovoltaic (PV) power, the adverse effects of its complex fault characteristics on grid relay protection are increasingly highlighted. Based on the introduction of the topology and the control strategy on low-voltage ride through of PV power, a theoretical solution method for solving the fault current of PV power is proposed by taking account of the DC bus voltage fluctuation, and a theoretical calculation model of its transient and steady state is established. The correctness of the theoretical results is verified by the numerical simulation results and low-voltage ride through (LVRT) experiment results. Furthermore, to gain a better understanding of the factors influencing PV power fault characteristics, the effects of several factors including proportional integral (PI) controller parameters, fault voltage sag depth, and PV power load level on PV power fault characteristics are analyzed by using simple variable method. The obtained results can provide a theoretical reference for the control parameter design and protection research of PV power.