A Fault Current Characteristic Analisis Method of Grid-Forming Converter with Current Limiting

Grid-forming converter can actively provide fast power support for the power system, and play a pivotal role in the new power system mainly based on new energy converters. Due to the weak overcurrent capability of the power electronics, the grid-constructing converter tends to operate in current-limiting mode under grid faults. In this paper, the transient analytical and numerical solutions for the filter inductance current are solved based on current limiting, taking into account the dynamic characteristics of the current loop; due to the fast nature of the current loop, the filter inductance current is therefore equated to a step function when solving for the fault output current in this paper. The fourth-order differential equation was reduced to the second order to simplify the solution, and the analytical solution of the grid-connect current was solved based on the state-space method; Numerical solutions for the grid-connect current taking into account the frequency dynamic characteristics are obtained for the grid-connect current based on the Runge-Kutta methods.