New approach to power line protection based upon the detection of fault induced high frequency signals

The authors outline the salient features of a protection technique for transmission lines which utilises the high frequency components of fault generated noise. The approach is based on the nonunit type scheme, which makes use of a stack-tuner circuit connected to the coupling capacitor of a capacitor voltage transformer. The stack-tuner is tuned to a certain frequency bandwidth and is arranged to act as a high frequency switch. The signals derived from the stack-tuner are used to determine whether the fault is inside or outside the protected zone