Fault Location Of Double-circuit Transmission Lines On Same Pole Based On Electromagnetic Time Reversal Theory

Compared with single-circuit transmission lines,double-circuit transmission lines on the same pole has larger transmission capacity and better economy,which makes it widely used in power system.At present,there are many researches on fault location of common single-circuit transmission lines,but the researches on fault location of double-circuit transmission lines on the same pole are relatively few,and the structure of double-circuit transmission lines on the same pole is quite different from that of single-circuit transmission lines,and the fault location process is more complex.Therefore,it is necessary to further study the fault location of double-circuit transmission lines on the same pole.In this paper,a new fault location algorithm based on electromagnetic time reversal theory is proposed to solve the complex problem of double-circuit transmission lines on the same pole.First,the fault recording device is used to record the change of fault current on both sides of the line,and then the line is decoupled by six-sequence component method.After decoupled,six sequence components are obtained on both sides of the line.For the double-circuit transmission lines on the same pole with the same voltage level,the positive sequence components of the six sequence components are extracted for fault location.For the double-circuit transmission lines on the same pole with different voltage levels,the positive sequence components of the first circuit line or the second circuit line are extracted line positive sequence component is used for fault location.Then,the wavelet function is used to decompose the positive sequence components of fault location on both sides of the line,the fault current features on both sides of the line is obtained,and then the fault current features on both sides are time-reversed.It is assumed that a fault occurs every other distance along the transmission line,and the effective value of fault current at the assumed fault point is calculated.The corresponding distance at the maximum effective value of current is the fault distance.In the simulation software of ATP-EMTP,the model of the double-circuit transmission lines on the same pole is built,and the distance measurement program is compiled by MATLAB software.According to different fault types,different transition resistances,different fault phase angles and different sampling frequencies,simulation results show that the algorithm is not affected by transition resistances,fault types and fault phase angles,and the ranging accuracy is high.the ranging accuracy will increase with the increase of sampling frequency,when the sampling frequency is 250kHz,the relative error of ranging results is 0.30%High ranging accuracy.It shows that the new fault location algorithm based on electromagnetic time reversal theory is suitable for fault location of double-circuit transmission lines on the same pole.