METHOD OF DETECTING AND LOCATING A HIGH-RESISTANCE EARTH FAULT IN AN ELECTRIC POWER NETWORK

摘要

The invention relates to detecting and locating a high-resistance earth fault of an electric power network. In the method, the substation is measured at the neutral point voltage (Uo) in phasor format. According to the method, the phase leg voltages of the network are measured in phasor format, the zero-sequence voltage phasor representing the neutral point voltage (Uo) is formed as the phasor sum of the measured phase leg voltages, the zero-sequence impedance (Zo) is computed by means of a network model, whereafter the zero-sequence voltage (Uo) is compared in phasor format with the phasors of the network phase leg voltages (Uv) and the resultant zero-sequence impedance (Zo) of the network, and from these computed variables are derived the fault impedances (Zf) for each phase leg, whereafter the faulted leg is identified as the leg having the greatest value of the real part of the fault impedance (Zf).