Online condition monitoring algorithm for element failure detection and fault location in double wye shunt capacitor banks

Abstract

Failure in quick detection and location of internal failures in Shunt Capacitor Banks (SCBs) may lead to the negligence of necessary repair processes, consequently laying undesirable effects on the power system operation. This paper puts forward a failure detection and fault location method in SCBs with the double wye connection. The proposed method provides a criterion for relay decision-making based on the neutral voltage and current fundamental phasor component, capable of distinguishing the faulty capacitors and determining the number of capacitor failures in the case of multiple faulty phases. The proposed algorithm can be applied for double wye SCBs considering different protection designs, namely fuseless and internally fused units. The proposed method is designed to monitor and detect consecutive failures based on the existing data from commercial relays. Implementation and performance evaluations are conducted in PSCAD and MATLAB software and also with the help of practical data. Performance evaluations are conducted under different circumstances, namely harmonic distortion and voltage unbalance conditions, multiple internal fault locations, and external faults from the grid. Simulation results show the significance and salient features of the proposed method under different conditions.