Impact of MOV Operation on Power Quality in transmission lines compensated by TCSC

TCSC as a dynamic system, besides its capability in increasing power transfer in transmission lines, can be used to enhance different power system issues. TCSC´s different advantages can be classified as steady-state and transient ones. During a fault, TCSC can enhance power quality by limiting the current and help to keep the voltage as high as possible. Different modes of TCSC have different effects on power quality. In this regard the MOV has a salient role in soft transferring from one mode to another. If the MOV is not triggered during TCSC transition modes, considerable voltage fluctuations are observed that last for a relatively long time. This is not favorable when sensitive loads are connected to the bus that a transmission line with TCSC is available. These fluctuations are not favorable to protective relays, too. In this paper, the impact of MOV of a TCSC on power quality is investigated. Different operating modes of TCSC and their behavior with/without triggering of MOV is simulated and analyzed.