Study On Single-ended Fault Location Algorithm Of Traveling Wave For Series Compensated Transmission Lines

Due to the reverse distribution of energy sources and load centers in China,longdistance high-voltage transmission has become an important way to solve this problem.With the development of flexible transmission technology and capacitor manufacturing technology,especially the emergence of new low-loss full-film capacitors,series compensation technology is more and more widely used in long-distance high-voltage transmission system.The series compensation technology brings economic benefits,but also brings difficulties to the fault location of transmission lines.Since the seriescompensation capacitor destroys the uniformity of the line impedance and generates a discontinuity of the wave impedance,the conventional fault location method cannot be applied.Moreover,the overvoltage protection component MOV has nonlinear voltampere characteristics.These factors will have a significant impact on the fault location method of the line.Therefore,fault location of series compensated transmission lines has become an urgent problem to be solved.Firstly,this paper introduces the main structure and working principle of the series compensation device,and compares and analyses the three protection modes of the series compensation device.The generation mechanism and transmission characteristics of traveling wave are expounded.The distortion and attenuation of traveling wave are studied from the point of view of energy,and the main reasons leading to its attenuation and distortion are analyzed.Secondly,the influence of series compensation capacitor and protective element MOV on traveling wave ranging is deeply studied in combination with the working principle of the series compensation device and the propagation characteristics of the traveling wave.Because of the existence of series compensation capacitance,the second traveling wave head is difficult to identify,so the single-ended method can not be directly applied,while the double-ended method is not affected.By analyzing and simulating the amplitude and phase response of the traveling wave at the series compensation capacitance,it can be concluded that the high frequency component of the fault traveling wave is not affected by the series capacitance.In addition,by constructing the simulation model of MOV in PSCAD,the on-time is simulated and analyzed.Finally,according to the conclusions and simulation results,a new single-ended traveling wave ranging algorithm for series compensation transmission lines is proposed.The algorithm only uses the information of one measuring point at the midpoint of the line.Firstly,the fault section is determined,and then the precise location is carried out.The fault section and arrival time of traveling wave can be accurately calibrated by synthesizing the polarity of initial traveling wave head and the polarity and amplitude of modulus maximum.The effects of fault points,bus terminals and series compensation devices on traveling wave propagation characteristics are fully considered.In addition,through specific calculation and analysis,it is proved that the transient traveling wave generated by MOV does not affect the algorithm.The robustness of the algorithm is analyzed by building a simulation model of series compensation transmission lines.The results show that the algorithm is not easily affected by the installation position,compensation degree,line length and different fault conditions.This algorithm has high accuracy and good robustness.