The Influence of TCSC Devices on Distance Protection Tripping Characteristic

The Thyristor Controlled Series Compensator is part of the Flexible AC Transmission System device category that uses series compensation to regulate active and reactive power flows. This device changes its impedance value depending on the firing angle of its two thyristors placed in antiparallel. The distance protection has the role oflocating the short-circuits present on the line, by measuring the impedance at one of the ends of the line and of trip the circuit breaker with a delay depending on the distance to the short-circuit. The paper highlights some problems that may appear in the correct functioning of the distance protection, due to the change in the impedance of the network. Also, the strengths and weaknesses of the main types of operating characteristics are presented.