Studies of an Algorithm of High Speed Travelling Wave Differential Protection for EHV/UHV Transmission Line

With the EHV/UHV power system development, the ultra high speed protection has been developed. Traveling wave differential protection has ultra-high speed, high sensitivity and selectivity. It does not be affected by the distributed capacitive current, busbar structure, fault resistance, current transformer saturation, etc. A new algorithm of travelling wave differential protection proposed for the EHV/UHV transmission line. It throws off noises with morphological gradient filter, and takes out the head of traveling wave, as well as the time of the head arriving. The algorithm is structured by the integraphs of traveling wave and a method of distinguishing lightning wave. Analysis and simulation results show that the new method has high speed and reliability, and can be employed as the primary protection of EHV/UHV transmission line.