A Novel Measuring Method of Capacitive Current for Ungrounded Distribution Systems

The measurement of grounding faults caused capacitive current is the foundation for Petersen-coil installation, tuning, and it´s capacity choosing in distribution systems. A novel measuring method of the capacitive current is proposed in this paper. A constant frequency current signal is injected from the secondary winding of zero sequence voltage transformer into the distribution system. The signal generated zero sequence voltage and phase voltage are measured. The capacitance to ground and the capacitive current are thus calculated with the transformer parameters influence considered. Theory analysis and simulation experiment results show that the proposed method does not need to change distribution system topological, it has no influence in power system normal operation, and it is with safety, fast, and high accurate.