Study of a Combined Surge Protective Device for a Relay Protection Circuit in a UHV Converter Station

Yuqi Zhang,Jianfei Ji,Weidong Zhang

doi:10.1109/access.2020.3020374

Abstract

This article focuses on the problem that the voltage recovery time of relay protection circuits in converter stations is too long under lightning surges. A surge protective device (SPD) in a relay protection circuit in an ultrahigh-voltage (UHV) converter station is investigated. Based on the action characteristics of a gas discharge tube (GDT) and metal oxide varistor (MOV) under a 1.2/50 μs lightning surge, the equivalent circuit model of a series-combined SPD is established. In the equivalent circuit model, this study considers the breakdown voltage, nonlinear impedance, parasitic capacitance, stray inductance and other parameters of GDTs and MOVs. Simulation analysis shows that a series-combined SPD can significantly increase the residual voltage and shorten the voltage recovery time of the protected system. To verify the simulation results, a test platform based on a low-voltage DC voltage divider was built for the lightning surge test. The test results are consistent with the simulation results, verifying that a series-combined SPD can meet the dual surge protection requirements of peak suppression and fast voltage recovery.

Highlights

The surge immunity test is an important test to evaluate the immunity of electrical and electronic equipment [1], [2], and it mainly simulates the unipolar surge caused by lightning and switching transient overvoltage
Compared with the protection measure of using a gas discharge tube (GDT) alone, connecting an metal oxide varistor (MOV) in series can increase the residual voltage of the protected system after the seriescombined surge protective device (SPD) action
LIGHTNING SURGE TEST BASED ON A LOW-VOLTAGE DC VOLTAGE DIVIDER The simulation results show that a series-combined SPD can effectively increase the residual voltage and shorten the voltage recovery time of the protected system

Summary

INTRODUCTION

The surge immunity test is an important test to evaluate the immunity of electrical and electronic equipment [1], [2], and it mainly simulates the unipolar surge caused by lightning and switching transient overvoltage. To meet the simulation requirements in the follow-up surge protection design, this article builds an equivalent circuit model that can accurately simulate the MOV action characteristics under a 1.2/50 μs lightning surge. PARAMETER ANALYSIS OF A SERIES-COMBINED SPD It can be seen from the study of GDT breakdown characteristics that a GDT can effectively reduce the peak value of transient overvoltage. Compared with the protection measure of using a GDT alone, connecting an MOV in series can increase the residual voltage of the protected system after the seriescombined SPD action. A series-combined SPD can effectively suppress a surge and recover the working voltage of the protected system within 80 ms, which can meet the dual requirements on the surge protection characteristics in the actual project. The voltage waveform of 50 resistance is recorded

PARAMETER SELECTION FOR A SERIES-COMBINED SPD

SIMULATION ANALYSIS OF A DC VOLTAGE DIVIDER

CONCLUSION