Grounded-fault protection based on DC component ratio

ZHANG Min; ZHOU Xuan

doi:10.11799/ce202311049

Abstract：Aiming at the poor effectiveness in practical application of small and medium current fault line selection methods in high-voltage power supply systems,taking the actual parameters of the Erlintu 35 kV box transformer as an example,the transient analysis of single-phase leakage faults caused by the grounding mode of the arc suppression coil in the 10 kV system was studied using theoretical analysis and numerical simulation,and the fault line selection criteria were obtained.Firstly,by solving the differential equations of equivalent circuits,the calculation formulas for zero sequence current of non fault lines and zero sequence current of fault lines were obtained,and MATLAB script program was used for programming verification;Then,the relationship between various electrical quantities and grounding resistance was described in detail,and it was pointed out that the initial phase of the fault phase voltage at the moment of grounding fault is an important factor affecting the transient process;The calculation methods for the DC component were proposed using Fourier transform and Fourier algorithm,respectively,and which were verified with actual parameters.Finally,MATLAB/SIMULINK simulation was conducted to verify the correctness of the equivalent circuit and theoretical analysis,as well as the accuracy and universality of fault line selection criteria.