High Impedance Fault Detection in Real-Time and Evaluation Using Hardware-In-Loop Testing

High Impedance Fault (HIF)is a low fault current event which cannot always be efficiently detected or cleared by conventional protection systems. Voltage or current signal distortions are often a possible indicator of HIF signatures which need to be carefully analyzed. This paper proposes a new technique based on second-difference approach to detect signal distortions. The technique does not require large database and is computationally very lightweight. The performance of the proposed technique is compared against commercial protection relays connected in Hardware-in-Loop (HIL)mode to a Real Time Digital Simulator (RTDS)simulating HIF in a IEEE 9-bus system. Test result evaluation show that the proposed technique is accurate and dependable.