Zero Sequence Parameters Measurement for Ineffectively Earthed Power Systems

Most distribution systems utilize ineffectively grounded sources to restrict the residual current for single-phase ground fault, so as to reduce outage and shock hazard. In practice, with the system expansion and topology changing, the residual current and zero sequence voltage of ground fault varies dynamically, so that some arcing ground faults easily cause over-voltage and induce multiple faults. In order to improve it, a new method for zero sequence parameters measurement based on the principle of resonance measurement is proposed in this paper. And the prototype for zero sequence parameters measurement has been developed, which has been tested in power system for several years. Results show that the zero sequence parameters measurement is with high precision and can be used for incipient fault detection and predictive maintenance.