# Double closed loop PI control with full compensation arc elimination based on zero sequence voltage of neutral point

## TL;DR

This paper proposes a dual-closed-loop PI control method to eliminate arcs during grounding faults by stabilizing the neutral point voltage and fault phase residual voltage.

## Contribution

The novel dual-closed-loop PI control algorithm improves arc suppression by using neutral point and fault phase voltage feedback for controllable voltage sources.

## Key findings

- The dual-closed-loop PI control stabilizes the controllable voltage source's output waveform during grounding faults.
- The proposed method reduces fault phase residual voltage to below 10 V, ensuring reliable arc extinction.
- Simulation and low-voltage tests confirm the algorithm's stability and feasibility across varying transition resistances.

## Abstract

Aiming at the problem of zero sequence voltage generated by unbalance parameters of line to ground, which affects arc suppression effect of grounding fault of controllable voltage source. By analyzing the influence of ground unbalance parameters on the arc suppression effect of controllable voltage source under different grounding modes, the mechanism of full compensation arc suppression based on zero sequence voltage of neutral point is revealed, and on this basis, a fully compensated arc suppression model of controllable voltage source controlled by double closed loop PI is established, and the deviation control is carried out by using the neutral voltage of distribution network and the voltage of fault phase supply. The residual voltage ring adopts the ground fault phase residual voltage for closed loop control. The simulation results show that the dual-closed-loop PI control algorithm can continuously stabilize the output waveform of the controllable voltage source. When the transition resistance is 0.1 ~ 10 kΩ, the residual voltage stabilization time of the independent controllable voltage source grounding method is 43 ms ~ 2.4 s, and the parallel arc suppression coil grounding method is 43 ms ~ 4.7 s. The proposed dual closed-loop PI control method for neutral point voltage deviation and fault residual voltage can stabilize the residual voltage of the grounded fault phase to below 10 V, forcing reliable arc extinction at the grounded fault point, exhibiting good stability. Low-voltage simulation tests have also proved the feasibility of the algorithm.