The design of a directional comparison protection for EHV transmission lines

The need for improved power line protection has led to the development of a directional comparison protection based upon new operating principles. This new protection has a number of advantages over conventional line protection relays. The authors detail the operating principles of the protection, and consider the salient features of the new design. The operation of the protection is illustrated using the results of a study on a complex power system, where the fault waveforms are distorted by high frequency transients