Management Relay for Assisting Distance Relays in Series Compensated Transmission Lines

The need for power is increasing every day in the world. In order to meet the power demand, numerous power plants are being built. Adding new power plants on available transmission lines leads to overloading problem. As a solution to this, series capacitors are used in transmission lines. Series capacitors increase the active power transfer capability. Also, it has a positive effect on system stability and voltage profile. However, on the contrary to the positive effects of series capacitor, it has some negative effects on distance relays which protect the transmission lines. In case of a short-circuit fault, the distance relays, depending on the location where the fault occurred and the capacitor effect might not see the fault that occurs on the line it protects or might see the fault on another line. In this study, a management relay was developed in order to prevent maloperations of distance relays due to capacitor effect. The developed relay identifies the faulted line in case of a short-circuit fault and sends tripping/blocking signal to the distance relays that might malfunction. At the end of the study, the verification of the management relay is carried out with various scenarios, and it is seen that the relay functions effectively during short-circuit simulations.