Study on traveling-wave differential protection for series compensated line

The problems of traveling-wave differential protection when it was used to transmission lines with series compensator were analyzed. The transmission line between relay location and the compensated capacitor is uniform transmission line although the impedance uniformity of transmission line is broken by the compensated capacitor. The traveling-wave equation is applicable in the transmission line between relay location and the compensator. Based on the above analysis, a novel scheme of traveling-wave differential protection was proposed for transmission lines with series compensator. The methods to calculate the differential current of fault phase and sound phase were discussed. The proposed method can eliminate the influence of capacitor current. The sensitivity and security can be realized. The scheme's accuracy has been verified by EMTP simulation. © 2009 Chin. Sco. for Elec. Eng.