Insulation monitoring and diagnosis is a condition-based maintenance and essential for an economic usage of high-voltage equipment. Appropriate monitoring and diagnosis before severe faults occurs makes it possible to control and operate a power system in a more reliable, effective, and sustainable way. Compared to other monitoring techniques such as chemical and thermal techniques, partial discharge (PD) monitoring seems to be the most promising methodology for detecting possible dielectric breakdown, aging and, ultimately, faults in power system components. PD is indeed an important indicator of an insulation condition in medium voltage (MV) and high voltage (HV) systems. The PD phenomenon is exhibited in various observable forms such as electrical, mechanical, optical and electromagnetic energies. The objectives of this paper were to present the application of on-line PD measurement and monitoring technology for the insulation condition assessment in medium and high voltage systems. The paper presents some of the sensor technology used to measure power cables, switchgear, transformers, and rotating machines for on-line PD. The paper also includes case studies of past experiences carried out by authors when using on-line PD measurement in various MV & HV assets in Thailand. Three cases studies are presented; generator, transformer and gas insulated switchgear. The efficiency and accuracy of on-line PD measurement was indicated by burn mark at equipment part as analyzed via partial discharge measurement.

Application of On-line Partial Discharge Measurement for High Voltage Equipment in Thailand

Electromagnetic waves on Partial Discharge (PD) that occur in Gas Insulated Switchgear (GIS) have frequency value in Ultra High Frequency (UHF) range (300 MHz – 3 GHz). So that, PD waves in GIS can be detected using UHF Antenna sensor. In this paper, the new design of UHF antenna to detect PD in GIS is simulated. Antenna design is obtained by combining the bowtie and dipole antenna designs to produce a wider bandwidth. The Simulation result shows that the total bandwidth obtained from the antenna design is 1581 MHz. 

Improving Antenna Performance by Combining Dipole and Bowtie Antenna for Partial Discharge Measurement in Gas Insulated Switchgear

Ultra high frequency partial discharge detection method has advantages in interference immunity and detection sensitivity, and this paper aims to design online partial discharge monitoring system including ultra-high frequency sensors, data acquisition system and software system design for operating 126kV gas insulated switchgear. In the experiment, a chamber of 126kV GIS is selected as the solid model and the typical partial discharge source is also designed for study. The experimental result shows that the detection system can effectively avoid the space disturbance which is difficult to suppress by conventional methods of electrical measurement and other disturbances, and it accurately detects the partial discharge signal and identifies the type of discharge based on the signal spectrum. This paper also studies the influence factor of ultra high frequency signal measurement using the model and lays a basis for in-depth study of GIS partial discharge monitoring based on ultra high frequency method

Shuguang Sun

Papers

Study of the online monitoring for GIS partial discharge based on UHF method