Development of condition monitoring techniques for SF6 alternatives in high voltage plant

With a drive to reduce the use of SF6 in the power sector, several candidate gases are now commercially available or under evaluation for use in gas insulated high voltage plant. PD monitoring has been established as means for condition assessment of SF6 filled equipment with initial studies demonstrating its potential feasibility for use in alternatives. A project is proposed to fully explore the application of PD detection to SF6 alternative candidate gases, in particular for medium voltage and high voltage switchgear. Propagation of acoustic and electromagnetic energy will be investigated along with detection in different switchgear designs. Laboratory and field measurements will be made on both SF6 and its alternatives to examine the occurrence of PD, characterise different defect types and better understand the potential degradation to the insulation system.

A practical and realistic approach will be taken into this research. Different defect types will be collected from equipment that were decommissioned in an attempt to find relevant defects to match the literature. Modeling software will be used throughout this research to calculate and model different experiments and parameters prior to designing a methodology and test setup. This research aims to test various SF6 alternative insulating gases and different defect types therefore a methodological approach will be taken to reduce the overall initial rounds of testing due to the large sample size. Based on the outcome of the small-scale results, the testing will move to real size HV GIS to perform long term monitoring test at a real outdoor substation environment.