Cross-Line Same-Phase Successive Faults Detection in Flexible Grounding Distribution Systems Based on Vertical and Horizontal Criteria

When cross-line same-phase successive faults (CSSFs) occur in a distribution network, the second fault makes the zero-sequence voltage consistently exceed 15% of the phase voltage, resulting in the existing detection devices not being able to return, which makes the fault persist for a long time and endangers the stable operation of the power grid.To address this problem, we propose a fault detection method based on vertical and horizontal double criteria. First, the zero-sequence current and voltage features are analyzed for a flexible grounding system when the grounding mode changes during the CSSF period. Second, constructing two boundary cases calculates the zero-sequence admittance modulus of the first and second faulty feeders. Finally, vertical criterion 1 is constructed because the fault feeder’s zero-sequence admittance modulus is greater than the healthy feeder. Horizontal criterion 2 is constructed because the faulty feeder’s zero-sequence admittance modulus ratio is greater than the healthy feeder. PSCAD simulations and field tests show that the method can accurately detect CSSF in flexible grounding systems without being affected by current transformer (CT) reversal, missing data, strong noise, and intermittent arcing.