Detection of high resistance earth faults in medium voltage networks using higher harmonics

The paper presents a method for detecting non-linear high resistance earth faults in compensated medium voltage networks, based on the criterion of reactive power of higher harmonics of zero sequence current and voltage. Harmonics content of currents and voltages as the function of network parameters and nonlinear fault resistance was estimated. The model of earth fault protection using that criterion was described. Detection examples of low and very high-resistance earth-faults were attached.