Experimental tests and analysis of electrical discharges in low-pressure media under non-uniform electric fields
Partial discharges (PDs) are localized electrical discharges that only partially bridge the insula- tion between conductors and are a major contributor to insulation degradation in high-voltage systems. While PD phenomena at atmospheric pressure have been extensively studied, their behaviour under r...
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| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/457187 |
| Acceso en línea: | https://hdl.handle.net/2117/457187 |
| Access Level: | acceso embargado |
| Palabra clave: | Electric power systems High voltages Electric discharges Sistemes de distribució d'energia elèctrica Alta tensió Descàrregues elèctriques Àrees temàtiques de la UPC::Enginyeria elèctrica::Alta tensió |
| Sumario: | Partial discharges (PDs) are localized electrical discharges that only partially bridge the insula- tion between conductors and are a major contributor to insulation degradation in high-voltage systems. While PD phenomena at atmospheric pressure have been extensively studied, their behaviour under reduced-pressure conditions remains insufficiently characterized, despite its relevance for aerospace and high-altitude applications. This thesis investigates the influence of air pressure on the waveform characteristics of corona partial discharge pulses generated under alternating current (AC) voltage excitation. An experimental setup was designed and implemented to generate and measure corona discharges under controlled low-pressure conditions ranging from 5% to 100% of atmospheric pressure. Two electrode configurations were analysed—rod–plane and sphere–plane—in order to assess the influence of electric field geometry. Partial discharge measurements were per- formed at the corona inception voltage (CIV), defined as the minimum voltage at which corona activity is detectable, for each pressure condition. A dedicated data-acquisition and processing workflow was developed in MATLAB to extract time-domain waveform parameters, includ- ing pulse amplitude, duration, rise and fall times, width, charge-related indicators, statistical moments, and temporal and amplitude centroids. The experimental results demonstrate that air pressure has a pronounced effect on PD pulse waveshape. Below approximately 30% of atmospheric pressure, pulse amplitudes and charge- related quantities decrease, while pulse duration, rise time, and decay time increase, indicating slower discharge development due to reduced air density and lower ionization probability. At higher pressures, pulses become shorter and steeper, reflecting faster avalanche processes and stronger space-charge effects that limit discharge growth. The combined analysis of multiple waveform parameters reveals consistent correlations between pressure, pulse asymmetry, and energy distribution within the discharge. The findings of this work contribute to a clearer understanding of corona PD behaviour un- der reduced-pressure conditions and provide a waveform-based interpretation of discharge de- velopment mechanisms. The results are particularly relevant for aerospace electrical systems, where operating pressures correspond to conditions associated with high-energy PD pulses. The developed experimental methodology, signal-processing framework, and pulse-shape syn- thesis approach offer a foundation for future studies addressing frequency effects, insulation ageing, and risk assessment in low-pressure high-voltage environments. |
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