Field Test and Analysis of Partial Discharge on GIS Under Impulse Voltage

Abstract: It is shown that many GIS devices still have insulating faults even after they have passed partial discharge test under power frequency voltage. Hence, it is necessary to experimentally study the partial discharge in GIS under impulse voltage so as to timely identify internal incipient faults and to insure stable and safe operations of equipment. We designed a set of partial discharge detection devices which could be conveniently applied in the field experiment considering the conditions of impulse voltage experiment on the basis of investigating the necessity of partial discharge of GIS under impulse voltage, and applied the device in partial detection on several 800kV breakers and GIS devices of 750kV substation. Moreover, we discussed anti-interference measures in field experiment. The results indicate that the test device is effective. 

Key words:  Impulse voltage, partial discharge, GIS, SF6 switchgear, PD detection, field test technology  

1. Introduction

GIS (gas-insulated metal-enclosed switchgear) is one of the most important electric equipment in the grid power. Its operation reliability is directly related to safety and stability of the whole power grid. However, with large-scale construction of high-voltage power gird and wide application of GIS equipment, the manufacturer is forced to delay the delivery of equipment because of problems of design, production, technologies, materials and main accessories etc. Many faults occur during the transportation, installation, debugging and operation. Causes of equipment faults are divided into several aspects, such as product design, production technologies, outsourcing parts, on-site installation quality, which may expose in the type test, field hand-over test and equipment operation. In order to avoid GIS faults and ensure the safety of electric system, people in the industry are searching for more reliable methods by trial and error to guarantee GIS quality and improve the diagnosis level of GIS insulation condition.