Performance Evaluation of Power Swing Blocking in Compensated Transmission Lines

Traditional and modern compensation devices can increase power flow limit and enhance voltage drop in transmission lines. However, these systems can cause to malfunction of distance relays utilized to protect transmission lines. While compensation devices can effect distance relay operation, some disturbances like power swings are significant risk to ability of distance relays to distinguish faults. Power swing blocking (PSB) methods are used to discriminate faults from power swings. This study focuses on efficiency of conventional PSB methods when transmission lines are compensated with various compensation devices such as series capacitor (SC), thyristor-controlled series capacitor (TCSC) and static VAR compensator (SVC). A test system is simulated on PSCAD under various operating conditions. Conventional PSB methods (swing center voltage, reactive power change and change rate of impedance) are tested under these scenarios. The study revealed that compensation devices significantly affect the accuracy of PSB algorithms, therefore it is recommended to develop an adaptive PSB method to block power swing in the case of various operating conditions.