A Study to Resist Conduced Interference from GIS Bus-Charging Currents Switching for Electronic Current Transformer

Song Bai ,Yi Li,Mingzhe Rong,Fanding Yue,Xiaohua Wang,Chuanchuan Wang ,Lang Zeng

doi:10.3390/electronics10080957

Abstract

In this paper, we study the conducted interference to an electronic current transformer introduced in the process of bus-charging currents which are caused by switching a gas insulated switchgear (GIS) disconnector. To cope with these issues, the EMTP-ATP and Matlab/Simulink software are used to carry out equivalent modeling simulations and experimental research, respectively. More specifically, the very fast transient current generated by disconnector switching (DS) is used as the input source of the equivalent simulation model of the Rogowski coil, and the characteristics of conducted interference waveforms of the Rogowski coil, the active integrator and filter outputs under single and multiple breakdowns are analyzed step by step. Moreover, several anti-interference methods are proposed to improve the resistance to the high-voltage and high-frequency conducted interference for the Rogowski coil, such as reducing the Rogowski cut-off frequency, increasing the transient voltage suppressor (TVS), active filter, and Cy capacitor. Besides, the study also reveals that the residual charge of the integral capacitor will discharge with a time constant τ = 1 s after arc quenching with the first-order discharge circuit, which is composed of the feedback resistance and the integral capacitor C. Lastly, the experimental results demonstrate the correctness of the modeling method proposed in this paper and the effectiveness of anti-interference measures.

Highlights

It is known that very fast transient overvoltage (VFTO) and very fast transient current (VFTC) can be generated frequently by multiple prestrikes and restrikes when the disconnector in air insulated switchgear (AIS) or gas insulated switchgear (GIS) switches capacitive load
The GIS electronic current transformer (ECT) sensor is highly integrated with GIS, and sampling units are installed on the enclosure or chassis of GIS, which is in a bad electromagnetic environment [5]
The results of this paper can be summarized as follows: 1. During the switching process of the disconnector, the VFTC produced with the VFTO is the root of conducting interference generated by the GIS ECT

Summary

Introduction

It is known that very fast transient overvoltage (VFTO) and very fast transient current (VFTC) can be generated frequently by multiple prestrikes and restrikes when the disconnector in air insulated switchgear (AIS) or GIS switches capacitive load. Despite the progress reported in the above references, there are some common problems in the current research on conducted interference of electronic current transformers: (1) the cut-off frequency of the Rogowski coil exceeds 100 kHz, even up to 1 MHz, but the protection of the power frequency system only needs 1–13 harmonics Under this setting, an unreasonable parameter design can cause serious waste and may fail to effectively attenuate the VFTC from the perspective of the sensor. This paper takes the test duty 3 of the GIS disconnector switching bus-charging currents as the research object [18,19,20,21] and performs simulations and an experimental verification of the conduction interference of VFTC to ECT generated during the GIS disconnector opening and closing process.

Simulation Model of Electronic Current Transformer Sensor and Integral Filter

Immunity Test of ECT When Disconnector Switching Small Capacitive Current

Findings

Conclusions