290 / 2022-03-15 06:39:14

Phase Resolved Partial Discharge Patterns for CO2, N2 and Technical Air

prpd,partial discharge,gas insulated substation (GIS);,free moving particle,needle-plane,floating electrode

Compared to air insulated systems, Gas Insulated Substations (GIS) have advantages such as compactness and high reliability under harsh environmental conditions. However, they can be subjected to partial discharge (PD) activity when the electric stress within the as insulation exceeds a critical value. Over long periods of time, PDs can lead to progressive deterioration of solid and gas insulations. PDs can ultimately lead to the breakdown of the insulation and interruption of electrical power supply. PD detection is considered an effective way to identify insulation defects in GIS prior to breakdown. Phase resolved partial discharge (PRPD) pattern helps to obtain information on the phenomena that cause pulse distributions of PD. PRPD patterns present cumulative PD pulses relative to an AC cycle of the applied voltage and can provide information about the source, type and intensity of PDs. Three artificial PD-inducing defects are introduced in this paper: metal tip (MT), free moving particle (FMP) and floating electrode (FE). The electrical measurement of PD is based on the recommendations of the IEC 60270 standard, with a high frequency current transformer (HFCT) detecting the PD current pulses as they pass through ground. The gases utilised for these experimental tests are CO₂, N₂ and technical air. PRPD patterns are obtained for each PD-inducing defect at 1, 2 and 3 bar gauge of pressure. PRPD patterns are going to be compared at different levels, including at inception and further stages of PD development in each defect.