Principle of Flexible Ground-Fault Arc Suppression Device Based on Zero-Sequence Voltage Regulation

Bishuang Fan,Chao Zhuo,Josep M Guerrero,Kun Yu,Ganzhou Yao,Xiangjun Zeng,Wen Wang

doi:10.1109/access.2020.3047188

Abstract

Single-line-to-ground (SLG) fault arcs cause the intermittent over-voltages, leading to short circuits within large-scale area. In this paper, a flexible arc suppression device is proposed, which adopts a zigzag grounding transformer, multi-terminal breakers and an isolation transformer to regulate zero-sequence voltage. Principle of zero-sequence voltage regulation (ZVR) and arc suppression method is presented. By carefully choosing the secondary side voltages of grounding transformer as the input of isolation transformer, the zero-sequence voltage is nearly constrained to the opposite of faulty phase supply voltage, and the ground-fault current is limited to a very small value. This device has high adaptability for low-resistance ground fault as it doesn't adopt any electronic apparatus. A 10kV prototype was established and multiple fault conditions were experimented to verify the effectiveness of the proposed ZVR device and its arc suppression principle.

Highlights

In power system distribution network, most of the reliability problems originate from single-line-to-ground (SLG) fault
We assume SLG fault happens in phase C, the circuit of the whole system of Fig. 1 can be simplified to Fig. 4, where Z denotes the impedance of the distribution network and is shown in (6), where YX is the phase-to-ground admittance, i.e., YX = jω0CX + 1/RX(X = A, B or C) and ω0 denotes the fundamental angular frequency
Rigorous researches on neutral ungrounded system of distribution network and strict principle of zero-sequence regulation method are analyzed

Summary

INTRODUCTION

In power system distribution network, most of the reliability problems originate from single-line-to-ground (SLG) fault. The voltage-controlled methods, such as the voltage-controlled inverter, limit the fault current by forcing the neutral-to-ground voltage to be the opposite of the faulty phase supply voltage without the measurement of the distributed parameters [13]–[15]. When the SLG fault happens, (e.g., phase C) [21], ZVR arc suppression device functions, a set of breakers Sbn and Scp are turned on to generate the line-to-line voltage ubc as the input of the secondary-side in the single-phase isolated transformer (T2), uq. The faulty phase voltage and the ground-fault current would be zero, which derives the basic arc suppression principle of the proposed device. The switch logic of multi-terminal breakers is listed in TABLE 1 and the speed of multi-terminal breakers is tested as milliseconds’ level

ZERO-SEQUENCE VOLTAGE REGULATION METHOD

SIMULATION VERIFICATION

EXPERIMENT VERIFICATION

Findings

CONCLUSION