Abstract
Flexible AC transmission systems are extensively dispersed in modern power systems to improve the performance, enhance the transmission capacity and increase dynamic/static stability margins. However, this result in deteriorating and/or malfunction of the protection devices particularly distance relays. This article comprehensively illustrates the consequences of embedding reactive power compensated device in the transmission network on the functionality of distance protection. Then, a simple, reliable and intelligent distance relay coordination scheme based on phase measurement unit is proposed for power system involving reactive power compensators. Modified IEEE 9-Bus system is used as study case. Matlab and its dynamic platform Simulink are used for investigating the performance of system under concern with different operating scenarios such as operation with/without conventional/proposed distance relay. The results prove the reliability, viability and wide-applicability of the proposed relay, as it could be used for any transmission network irrespective to the embedded reactive compensation device. Moreover, the proposed relay efficiently overcomes over/under reach problems of the traditional distance relay in the compensated lines.