Simulation of PD Characteristics of Closely Coupled Air Cavities Using MATLAB/SIMULINK

Air cavities are among the common sources of partial discharge (PD) activities in insulation. PD may lead to electrical insulation degradation and breakdown. The present study is carried out to investigate PD characteristics in closely coupled double cavities compared to single cavities in solid insulation. A modified three-capacitor PD simulation model is built in MATLAB SIMULINK. The coupling of the two 1.5 mm diameter identical cavities varied between 0.01 mm and 3.5 mm and the resultant PD characteristics captured. For comparison, simulations of PD activity of a single cavity of same dimensions were also conducted under the same voltage conditions. The findings are that the double cavity partial discharge magnitudes are greater when the separation distance between the cavities gets smaller compared to a single cavity. As the coupling distance increases, the PD magnitude becomes like that of a single cavity. The total PD pulses in one cycle of the closely coupled cavities is less than double the number of pulses in a single cavity of same dimensions. These findings are interesting as they give new perspectives on understanding PD characteristics in multiple cavities.