Pilot Protection Based on Energy Ratio of Differential Current for Outgoing Line From Renewable Power Plants
The wide application of power electronic devices in new energy power system has changed the fault characteristics of traditional power system,resulting in the decline of traditional protection action performance,and even the risk of false-operation and refusal-operation,which brings challenges to the safe and stable operation of power grid.By analyzing the similarities and differences between the differential current and the distributed capacitance current after the fault inside and outside the area,this paper makes it clear that there is an obvious difference in the energy between the line distributed capacitance current and the differential current after the fault.Then,using the characteristics that the differential current energy and the distributed capacitance current energy is very different during an internal fault,and the differential current energy of an external fault is basically the same as the distributed capacitance current energy,a new criterion of pilot protection based on the energy ratio of the differential current is proposed.The simulation results verify the feasibility of the protection algorithm.The proposed method can solve the problem of the decline of differential protection action performance after new energy access,adapt to different types of new energy stations,and has the ability to withstand excessive resistance.Compared with the existing protection based on the transient current characteristics of new energy,the proposed method has better action performance when the new energy power supply has weak output.
renewable energy grid connectionfault analysispilot protectionenergy ratio
国家科技期刊平台
NSTL
万方数据
维普
