Analysis of sympathetic inrush using network analysis approach in initial period of power symtem restoration

In the initial period of power system restoration, the generator unit regulating ability is limited. charging transformer without load would cause sympathetic inrush current. This would leads to mal-tripping of the protective relay that result in the failure of the restoration. Based on the equivalent circuit of two shunt-wound transforms, the mathematical representation between sympathetic inrush and main operating parameters is deduced using network analysis approach. After that, the influence of load power factor on sympathetic inrush current is analyzed deeply. The process of sympathetic inrush based on the model of actual situation is simulated and the analytical results is proved to is validated. The conclusion of this paper is valuable in understanding the generating reasons of sympathetic inrush current and avoiding restoration failure in initial period of power system restoration.