High-impedance faulty feeder detection for cross-country faults in distribution networks based on zero-sequence active power regulation

Abstract

The weak characteristics of high-impedance faults and the complex attributes of cross-country faults make faulty feeder detection of cross-country high-impedance faults difficult in medium-voltage networks. This paper deduces the zero-sequence equivalent circuit of cross-country faults through a three-sequence two-port network, analyzes the influence of grounding resistance on cross-country faults, and then explores the limitations of the traditional passive feeder detection methods. Moreover, this paper proposes a novel faulty feeder detection method for cross-country high-impedance faults based on zero-sequence active power regulation. First, based on the zero-sequence current varying characteristics under the regulation of zero-sequence voltage, construct a continuous adjustment region of zero-sequence voltage within the feeder insulation tolerance range. Next, based on the zero-sequence active power varying characteristics in each feeder, propose a discriminant formula for the zero-sequence active power fluctuation coefficient. Finally, adjusting zero-sequence voltage can actively amplify the differences in zero-sequence active power fluctuations between healthy feeders and faulty feeders and accurately select faulty feeders of cross-country high-impedance faults in medium-voltage networks. Various fault conditions are simulated in the PSCAD/EMTDC simulation and field test to verify the effectiveness of the proposed method. The proposed method can accurately identify all faulty feeders of cross-country high-impedance faults in the medium-voltage distribution network.

Keywords

• High-impedance faults
• Cross-country faults
• Flexible grounding
• Zero-sequence active power regulation
• Faulty feeder detection