Detection of transmission line faults in the presence of thyristor switched capacitor using discrete wavelet transform

The power system faults do occur in power system network and are more frequent in transmission and distribution systems. The behaviour of power system faults changes in the presence of FACTS devices. Accurate detection of these faults is essentially required for providing effective power system protection and relaying system. The relays must operate as fast and accurate as possible to switch off the faulted line in order to protect the system against the harmful fault effects. This paper presents the detection of power system faults on the transmission line in the presence of Thyristor switched capacitor (TSC). The power system faults such as line to ground (LG), double line (LL), double line to ground (LLG) and three phase fault involving ground (LLLG) has been investigated. An algorithm based on discrete wavelet transform and using squared detail coefficients has been utilized for detection of faults under investigation. The current drawn by the load in the presence of TSC and voltage at the point of common coupling (PCC) have been found to be key features for the detection of power system faults. The study has been performed using a test system and results have been validated in MATLAB/Simulink environment.