Impact of harmonics on the performance of over-current relays

This Paper investigates the impact of power system harmonics on the performance of over-current relays. Simulation is performed on the IEEE 30-Bus system with heavy penetration of non-linear loads using ETAP software. Simulation results show that with significant harmonic contents in the power network, a relay malfunction will occur and they will trip in a wrong sequence when there is a fault in the system.