Research On One-phase Adaptive Reclosure Of UHV/EHV Power Transmission Line

Automatic reclosing device is one of the effective measures to guarantee powersystem security and stability operation, and has been widely applied in theUltra-High Voltage/Extra-High Voltage (UHV/EHV) power system.However, theconventional automatic reclosing device can not distinguish between permanent faultand temporary fault, then reclosing on the permanent fault maybe produce a certaindegree harm on power system. Adaptive reclosing device can accurately recognizefault feature before reclosing, and avoids reclosing with the permanent fault. So,adaptive reclosing technology is helpful to improve the success rate of reclosing, andcan eliminate the second rush, ensures safe and stable operation of power system.This paper studies the fault modeling and simulation method of UHV/EHVtransmission line, and proposes new fault feature recognition algorithm andimplementing method of adaptive reclosing.Firstly, the common used fault recognition method and criterion of adaptivereclosing are analyzed, and the arc dynamic characteristic of first stage arc andsecond stage arc is discussed. Through the simulation analysis of the fault phasevoltage of UHV/EHV transmission line, fault phase voltage waveform of UHV/EHVtransmission line whether with shunt reactor or not is obtained.Furthermore, the wavelet packet transform, approximate entropy and sampleentropy algorithm are applied to analysis of transient signal in faulted transmissionline. Discussed the wavelet packet decomposition and reconstruction of the faultsignal, the frequency band division and so on. Approximate entropy and sampleentropy calculation of the electrical fault signal are analyzed.Finally, the arc voltage waveform of the fault transmission line is analyzed. Intransient fault, after tripping the circuit breaker, transient high-frequency componentof voltage of the fault phase is relatively stable before extinguishing the arc, also itpresents fluctuant trend; In permanent fault, the high-frequency component decaysfastly and monotonically. The wavelet packet transform and entropy algorithm areused to analyze distortion or complexity of fault signals, and a new adaptivereclosing method, as well as the new criterion, is presented. In different fault types,different locations and different fault grounding resistances, a large amount of simulations show that the new fault feature recognition algorithm and the adaptivereclosing implementing method are feasible and effective.