Longitudinal Direction Protection Method of AC/DC Hybrid System Based on the Difference in Polarity of Traveling Wave Current
The commutation failure of the inverter station in the AC/DC hybrid system causes the frequency deviation of the AC line,which affects the reliability of the longitudinal direction protection of the power frequency quantity.A longitudinal direction protection method of AC/DC hybrid system based on the difference in polarity of traveling wave current was proposed.The polarity difference between the initial traveling wave fronts of the current fault propagating to both ends of the protection constitutes the longitudinal protection when the internal and external faults occur.This method only uses the polarity difference of the initial traveling wave of the current to determine the direction,which eliminates the low reliability of the protection caused by the inability of the capacitive voltage transformer to accurately transmit broadband voltage information.And this method uses high-frequency current to calculate,which avoids the influence of frequency offset of AC/DC hybrid system.The simulation results show that the longitudinal direction protection based on the polarity difference of traveling wave current can accurately and quickly identify single-phase faults and multi-phase faults,which is suitable for AC/DC hybrid system.
AC/DC hybrid systemlongitudinal direction protectiontraveling wave current polaritywavelet transformationAC line
万方数据
维普
