Detection of Open-Neutral Fault in Low-Voltage Distribution Systems Based on Third Harmonic Energy Variation

Detecting open-neutral faults in low-voltage distribution systems is essential for ensuring system stability and protecting electrical equipment from potentially hazardous conditions such as over-voltage and under-voltage. Open-neutral faults, common in areas with load imbalances, can lead to significant safety risks, making accurate detection methods crucial. This paper introduces a novel detection approach based on variations in third harmonic energy. In the three-phase fourwire system without disconnection faults, the neutral wire channels third harmonic currents from nonlinear loads to the ground. However, when the neutral wire is disconnected, these currents are redirected to other loads, resulting in measurable shifts in third harmonic energy. By analyzing these energy fluctuations before and after a fault and applying set thresholds to distinguish faults from normal load variations, the proposed method effectively identifies open-neutral faults. Simulation results demonstrate high detection accuracy under various load conditions, even when load balance is maintained.