Dynamic Analysis of the Impact of TCSC on Distance Relay Operation

Abstract

TCSC and its protective equipment present very complicated impedance characteristic which could affect distance protection operation. Under earth fault conditions, changes of symmetrical sequence currents influence the relay characteristic, Mho, Reactance or Directional. This paper presents studies on the effects of control strategy of TCSC such as Constant Impedance (CI) and Constant Current (CC) techniques on the apparent impedance measured by distance relays during faults. The simulation results show that distance relays overreach and lose their directional integrity with different control strategies. The work shows that not only the relay maloperation for the compensated lines, but also operation of the relays on adjacent lines are affected by TCSC.