Transient Voltage UWB Online Monitoring System for Insulation Failure Analysis and Fault Location of GIL

Abstract

Transient voltage generated in ultra-high voltage (UHV) transmission system has a severe impact on the insulation state of gas-insulated transmission lines (GIL). In order to monitor the transient voltage process occurring in UHV GIL during operation, this paper constructs a transient voltage ultra-wideband (UWB) online monitoring system based on capacitive voltage division. This system has been applied in an 1100 kilovolt (kV) GIL utility tunnel project. It can be used to analyze the characteristics of the recorded transient voltage waveforms for distinguishing different types of insulation failure. In this paper, through the case studies in time domain and time–frequency domain, the case of SF6 gap breakdown and that of post insulator flashover have differentiated characteristics in instantaneous frequency. Additionally, a case of secondary discharge is successfully estimated through the time–frequency distribution of the transient voltage. In order to find the malfunctioning chamber of GIL rapidly, a two-terminal TW-based fault location method based on this monitoring system is developed in this paper. The case study validates the locating accuracy which directly support for shortening the maintenance time of GIL.

Distributed optical fiber sensing technology in operation status monitoring of GIL equipment

“…With the continuous promotion of the west-east power transmission project and the acceleration of regional power and energy interconnection, gas-insulated transmission lines with their advantages of large transmission capacity, long transmission distance, and good environmental compatibility have been put into operation in major power transmission constructions such as Tianshengqiao hydropower station, Xiluodu hydropower station and Sutong GIL integrated pipeline corridor in China Statistics show the reasons for the failure of GIL equipment, among which mechanical failures account for 2/3 [1]- [2]. Because GIL equipment applications are mostly extra-high voltage and closed structures, once a failure occurs, it will cause huge economic losses, so its fault diagnosis is of great significance to the safe transmission of electric energy and stable operation of the power grid [3]- [4]. Gas-insulated metal-enclosed transmission lines are an important supplement to overhead transmission methods under restricted geographical or environmental conditions and are widely used in China because of their significant advantages, such as high transmission capacity, low losses, environmental independence, high operational reliability, and space-saving [5]- [6].…”