Travelling wave distance protection-problem areas and solutions

The authors examine some problem areas and suggest techniques to improve the proposed distance protection based on travelling waves outlined by P.A. Crossley and P.G. McLaren (1983). A composite correlation output is used to recognize the reflection from the fault and distinguish it from other reflections from points behind the fault. The correlator output magnitude is also used to achieve UHS (ultra high speed) fault detection for close-up faults. Effects of fault inception angle are compensated. Fault-resistance effects and external faults are also examined