Analysis and Verification of Differential Protect Operation of AC / DC Hybrid Power

Abstract

In this paper, the characteristics of AC / DC hybrid faults are analyzed, and the influence of AC / DC hybrid power system on AC current differential protection is analyzed and discussed. When the DC commutation fails, the power frequency current injected into the AC power grid is ahead of its voltage. At this time, the phase angle between the power frequency current and the voltage will change, which will cause the action of the AC line fault. If the current decreases, the brake current will increase, as a result, differential protection refused to action. The PSCAD is used as the platform to simulate the differential protection operation. And the parameter identification based transmission line protection with shunt reactors is proposed. Simulation results show the correctness of the theoretical analysis.