Analysis of Cavity PD Characteristics’ Sensitivity to Changes in the Supply Voltage Frequency

Abstract

The supply voltage frequency effect on partial discharge (PD) phenomena has continued to draw research interest. Although most high voltage equipment operates at power frequency (50/60 Hz), testing is often done at different frequencies for various reasons. Despite some agreements and inconsistencies for the research findings of PD activity’s frequency dependence, there has been consensus on the recognition of the discharge mechanism parameters that influence how the supply voltage frequency affects PD activity. These parameters include statistical time lag, discharge area surface conductivity, and the residual charge decay. In this paper, a 3-capacitor model (ABC) is used to simulate how the changes in the discharge mechanism parameters influence PD characteristics as a function of the supply voltage frequency. The findings are that the phase-resolved partial discharge pattern (PRPDP) and PD repetition rate (PDRR) characteristics are more sensitive to variations in the probability of the seed electron availability at higher frequencies of the supply voltage. The opposite trend is observed for the cavity surface resistance. At lower resistance of cavity surface, the PRPDP and PDRR characteristics are more sensitive to changes in the supply voltage frequency than at higher resistances. The paper also confirms that incorporating equivalent resistances in the ABC model makes it more authentic than the model comprising of capacitors only.

Circuit Models of Q(t) Data and Analyses of Saturation Time Dependency on Delay Parameters

“…Importing the model of partial discharge appears to be good. One example of a circuit model that contains both a resistor and a capacitor is shown in [18]. Fig.…”

“…Q(t) measurement was first demonstrated in the 1970s by Takada et al [1], and the mechanism and structure of the circuit are almost the same as those of a leakage current detector, which can detect an extremely small electric current that indicates the incompleteness and/or the defects of electrical insulation inside insulators. In contrast to partial discharge (PD) diagnosis [17,18], whose main target is oscillating voltage, Q(t) measurement applies to DC voltage.…”

“…On the contrary to partial discharge [17,18], few studies have considered the circuit models. Previous research assumes the circuit model shown in Fig.…”

Residual charge effects on partial discharges' response to varying sub‐kHz voltage frequencies

“…The switch opens (extinguishes) the PD when V pd falls below V inc . The detailed algorithm for executing the extended 3‐capacitor PD model in MATLAB ® Simulink ® is presented in the authors' previous work [4].…”

“…In the physics of partial discharges, the key parameters that influence PD mechanisms are the externally applied electric field, the seed electron availability and the physio‐chemical conditions in the discharge area, including the space charge. In the authors' previous work [4], findings were presented on how cavity surface conductivity and the statistical time lag of seed electron availability influence how PD characteristics respond to variations in the externally applied voltage frequency. Among the findings, it is notable that the variation trend of PD characteristics in response to changes in the voltage frequencies is non‐monotonous in the voltage frequency range from 1 to 200 Hz.…”