Distance protection with dynamic thermal line rating enhancement

As the worldwide analysis of recent wide area cascading failures have shown, very often the main cause of blackout was mal-operation of the third zone of a distance protection relay. The load encroachment and power swing phenomena are the two dire problems to solve when dealing with the third zone of distance protection mal-function. The vast number of blackouts could have been avoided or the consequences lowered if the distance relay had not operated due to controlled impedance encroachment.This paper proposes a new approach to enhance the distance protection relay operation by introducing a new blocking algorithm. The algorithm is based on Dynamic Thermal Line Rating (DTLR) idea to restrain relay from tripping when conditions in electrical power system and weather conditions allow for it.