Impact of SVC on the protection of transmission lines

The impact of Static Var Compensator (SVC) on the apparent impedance seen by the transmission line distance relay is investigated in this paper. Analytical results are presented and verified by detailed simulations. It is shown that the connection type of the windings of the shunt coupling transformer of the SVC has a remarkable effect on the apparent impedance seen by the distance relay. Six different phase to phase and phase to ground measuring units of the distance relay are simulated to resemble the behavior of the relay. The impact of SVC is more pronounced on the apparent impedance seen by the phase to ground fault measuring units than the others as is shown by the results. Simulation results include different power system operating conditions. SVC control system settings and different fault-type scenarios. The impact of SVC on the relay tripping boundaries is also clearly demonstrated. Detailed and sophisticated models are used for simulating distance protective relay in a digital simulation environment. (c) 2012 Elsevier Ltd. All rights reserved.