A General Coordination Scheme for Zero-sequence Current Differential Protection on Series-compensated Multi-circuit Line

The present study of zero-sequence current differential protection (ZCDP) with series compensation has not considered the equivalent impedance characteristic of series compensation, and meanwhile cannot put forward a universal coordination scheme feasible for multi-circuit lines. In this paper, the equivalent impedance characteristic of the series capacitor (SC) device and the effect of SC on the operating characteristics of ZCDP under single-circuit and multi-circuit conditions are analyzed. Based on the analysis, a general coordination scheme for ZCDP on series-compensated multi-circuit line is proposed, of which the presented sensitivity coefficient is able to reflect the sensitivity of current differential protection. A power grid experiment is used to demonstrate the correctness of the analysis and the effectiveness of the proposed scheme.