Experimental Challenges when Measuring Partial Discharges under Combined DC and High Frequency AC Voltage

Abstract

The present paper reviews some of the challenges involved in designing and building an experimental setup for measurement of partial discharge under combined AC and DC voltage. A design of a modular test cell is discussed, as well as all parameters relevant to proper control of the experiment conditions. The described experimental setup is capable of producing sinusoidal AC voltage at a variable frequency up to 5 kHz superimposed a high DC voltage. The challenges related to intermittent noise reduction was remedied by placing the setup in a Faraday cage and controlling the setup from the outside by optical cables. All equipment in the test setup was connected to the power grid through low-pass filters.

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“…Applied AC fields increase the probability of PD accidents with each frequency cycle by redistributing space charge or residual surface charge at a discharge site after each discharge event [125]. As a result, the repetition of PD under AC fields depends on the frequency of applied voltage [126]. High-order harmonics increases the likelihood of PD by increasing voltage at a certain value to block space charge movement and by redistributing the net electric field in defect locations [64].…”