An Active Voltage-Type Grounding Fault Protection Method for Medium-Voltage Distribution Networks with Neutral Point Voltage Flexible Regulation

Intermittent arc grounding faults are common in medium-voltage distribution networks, and the arc cannot be extinguished without assistance. The application of existing arc suppression methods is limited due to the problems of large compensation residual currents, complex control circuits and large short-circuit currents. Therefore, an active voltage-type grounding fault protection method for medium-voltage distribution networks with neutral point voltage flexible regulation is proposed. The line voltage opposite to the fault phase is extracted from the auxiliary side of the Dyn1 distribution transformer, and it is fed to the neutral point. By adjusting the Dyn1 transformer ratio to regulate the neutral point injection voltage size, the residual voltage is reduced to below the arcing voltage, the arc is no longer reignited, and the fault residual current is eliminated. The simulation results of PSCAD/EMTDC software and the field test results of the 10 kV true distribution network prove that this method can reliably achieve arc suppression.