A Review of the Impact of TCSC Device on the Protection of Transmission Line

In this paper presents a analysis of the impact of TCSC on the protection of transmission lines. The Thyristor Controlled Series Capacitor (TCSC) is a type of Flexible AC Transmission System (FACTS) device used in power systems to dynamically control power flow and enhance system stability. However, its operation significantly affects distance protection, especially the apparent impedance measured by distance relays during faults. The simulation results show that distance relays overreach & getting unwanted trip signals and to overcome this impact further mitigation techniques are also discussed. Modern energy transmission system suffers from high voltage drop and reduced power transfer capability due to enormous load, therefore flexible AC transmission system TCSC devices are used to improve the power transfer capability of long transmission lines. Distance relays are used for fault detection on transmission lines by measuring the apparent impedance at the relay location. The impedance is compared with preset values (zones) to determine fault location and direction. TCSC is a series compensation device. It consists of a capacitor in series with the line, controlled by thyristors (via a thyristor-controlled reactor, TCR).