Applying pattern recognition in distance relaying. I. Concept

The principal application of distance relays is for the protection of essential subtransmission networks and transmission lines operating at EHV and UHV, whose performance depends on various factors. The task of selecting a universal operating characteristic for distance relays is difficult. Although, over the years, different characteristics have been in use, there is a general agreement that the quadrilateral characteristic is superior to other characteristics. This agreement is largely based on application successes. Authors introduce the concept of obtaining the operating characteristics by applying the method of pattern recognition. The principle provides a meaningful approach for generating an operating characteristic that is natural for the overhead line, i.e. by the reason that all possible factors that can affect the overhead lines performance, can be considered