LAUSR

Series compensation is generally used with long transmission lines to increase power transfer through the line and to enhance system stability. In the case of voltage source converter-based series flexible AC transmission system (FACTS) controller, an energy storage device can be incorporated at the DC bus which further improves control of real and reactive power flow. However, four-quadrant operation of FACTS controllers with energy storage device poses new challenges for the operation, control and protection of power system. Most commonly used protection scheme for long transmission lines, the distance relay, may not be reliable in case of lines compensated with series FACTS controllers. This paper proposes a new wavelet transform-based relay logic for fast and reliable detection, and classification of faults in a hybrid series-compensated long transmission line incorporating a passive series capacitor and static synchronous series compensator with energy storage device (SSSC-ES). The proposed relay logic is also able to accurately estimate the location of fault, and a wavelet transformbased boundary condition is used to discriminate between internal and external faults. It is shown through various simulation case studies that the four-quadrant operation of SSSC and fault resistance have negligible impact on the performance of the wavelet transform-based relay.