Research On One-Phase Adaptive Reclosure Of UHV Power Transmission Line

Automatic reclosing device is one of the effective measures to guarantee power system security and stability operation, and has been widely applied in the Ultra-High Voltage power system.However, the conventional automatic reclosing device can not distinguish between permanent fault and temporary fault, then reclosing on the permanent fault maybe produce a certain degree harm on power system. Adaptive reclosing device can accurately recognize fault feature before reclosing, and avoids reclosing with the permanent fault. So, adaptive reclosing technology is helpful to improve the success rate of reclosing, and can eliminate the second rush, ensures safe and stable operation of power system. This paper studies the fault modeling and simulation method of UHV transmission line, and proposes new fault feature recognition algorithm and implementing method of adaptive reclosing.Firstly, the common used fault recognition method and criterion of adaptive reclosing are analyzed, and the arc dynamic characteristic of first stage arc and second stage arc is discussed. Through the simulation analysis of the fault phase voltage of UHV transmission line, fault phase voltage waveform of UHV. transmission line whether with shunt reactor or not is obtained.Furthermore, the wavelet packet transform, approximate entropy and sample entropy algorithm are applied to analysis of transient signal in faulted transmission line. Discussed the wavelet packet decomposition and reconstruction of the fault signal, the frequency band division and so on. Approximate entropy and sample entropy calculation of the electrical fault signal are analyzed.Finally, the arc voltage waveform of the fault transmission line is analyzed. In transient fault, after tripping the circuit breaker, transient high-frequency component of voltage of the fault phase is relatively stable before extinguishing the arc, also it presents fluctuant trend; In permanent fault, the high-frequency component decays fastly and monotonically. The wavelet packet transform and entropy algorithm are used to analyze distortion or complexity of fault signals, and a new adaptive reclosing 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 adaptive reclosing implementing method are feasible and effective.