Investigation of TCSC controller effect on IDMT directional over-current relay

With the presence of FACTS controllers in power system transmission for enhancing the power system controllability and stability, the problem of coordinating protective relays becomes more challenging. The over-current relay is widely used in many protection applications throughout distribution network and the IDMT directional over-current Relay is one of the most important protection systems on transmission lines. Its function would generally be changed in presence of FACTS devices. In this paper a study for obtaining the direct effects of the varying reactance of the TCSC with respect to the firing angle alpha on short-circuit parameters of three phase fault and DOCR operating time is investigated. The simulation of the linear programming technique is performed in Matlab software environment. The case study is compared between compensated and uncompensated system. (C) 2015 The Authors. Published by Elsevier Ltd.