Fault Analysis of Grid-connected Inverter Station at Fault Initial Stage

In order to analyze the response characteristics of the grid-connected inverter system to the fault initial traveling wave at the fault initial stage of AC side and realize the analytical analysis of its fault characteristics, this paper establishes the equivalent model of the grid-connected inverter system. Firstly, the effect of grid-connected inverter and its boundary devices on the fault initial traveling wave at the fault initial stage is analyzed, and the grid-connected inverter system is simplified as Peterson equivalent circuit composed of impedance of the converter transformer and the LC filter. Secondly, based on the traveling wave propagation theory, the transfer function of the fault initial traveling wave propagating from the fault point to the PCC point is derived. In addition, according to the corresponding boundary conditions, the amplitude of the fault initial traveling wave under different fault types is solved. Finally, the simulation results verify the theoretical analysis.