Investigating Condition Monitoring of SF6 Alternatives in the Power Industry
SF6 has been widely used in gas insulated switchgear across the electricity networks. In the UK, it is estimated that the SF6-filled gas-insulated substations in both transmission and distribution networks consists of approximately 1,500 t of SF6. There is a strong drive for alternatives that possess significantly lower global warming potential, and several candidate gases are now being evaluated. Development of a suitable condition monitoring system tailored for new SF6 alternatives will help to promote the adoption of environmentally friendly insulating gases, which will accelerate the phase-out of a potent greenhouse gas in SF6.
HVPD and the University of Manchester have embarked on a six-month project to investigate condition monitoring techniques for gas-insulated switchgear that use alternatives with significantly lower environmental impact than SF6. The project has received funding from the Engineering and Physical Sciences Research Council (EPSRC).
HVPD provide test services and manufacture condition monitoring equipment for detection of partial discharge insulation degradation in high voltage equipment that is in service. Based in Manchester with offices in UAE, China, Australia and USA, HVPD service customers across the energy industry including generation, utilities and heavy industries.
The University of Manchester has recognised expertise in high voltage engineering and state-of-the-art facilities for insulation degradation testing in multi-stress analyses (temperature, humidity and pressure). It is home to the National Grid Power Systems Research Centre, and the largest high voltage research laboratory in the UK. It has facilities that can test up to 600 kV DC, 800 kV AC, and 2 MV impulse.
The project aim is to explore the practical aspects of partial discharge-based condition monitoring in a controlled environment. Partial discharge can occur in gas insulated equipment due to various defects such as protrusions on high voltage conductors, floating metallic particles or poor high voltage contacts. Testing has been carried out at The University of Manchester High Voltage Laboratory on a full-scale gas insulated demonstrator rated up to 550 kV with and without defects. The demonstrator has been energised and monitored continuously to evaluate partial discharge trends as they develop into insulation breakdown. Using a combination of internal sensors and recently developed externally mounted sensors, the electromagnetic radiation generated from partial discharge activity due to the defects has been monitored in the ultra-high frequency spectrum using the HVPD Kronos® monitoring system.
Further plans are to evaluate insulation performance of representative defects over a longer timescale using the full-scale demonstrator and a dissemination webinar which will be held at the end of the project.
This article was featured in the Winter 2021 Edition of the Institution of Engineering and Technology (IET) Partner News, of which HVPD are members. To view the complete publication, click here https://www.theiet.org/involved/partnerships/partner-news/current-issue/