Partial discharge

About: Partial discharge is a research topic. Over the lifetime, 13997 publications have been published within this topic receiving 102058 citations. The topic is also known as: PD.

Method of and apparatus for assessing insulation conditions

Abstract: A method of and apparatus for the detection of insulation deterioration in an electrical power supply system utilizes the detection of a progressive wave generated by a corona discharge or partial discharge due to such insulation deterioration. Sensing of said progressive wave may be effected by an apparatus comprising: a first coil having two primary windings, wound with the same number of turns and in the same direction, and a secondary winding, the primary and secondary windings being wound on a core whose magnetomotive force and magnetic flux density are roughly proportional to each other; a second coil composed of a primary winding and a secondary winding both wound on a core whose magnetomotive force and magnetic flux density are roughly proportional to each other; and an impedance circuit. Determination of the position of insulation deterioration may be effected by comparing the phase of the progressive wave at a reference point in a common bus with the phase of the progressive wave in each of the power supply lines branching off from the common bus.

PD characteristics of oil-pressboard insulation under AC and DC mixed voltage

Abstract: The insulation problem of converter transformers has become one of the core issues in HVDC system, which is receiving more and more attention. A converter transformer has complex structures and requires high insulation level. The voltage waveform which the converter transformer insulation withstands is different from AC transformers. In the valve side of the converter transformer, the insulation endures a mixed voltage of AC voltage, DC voltage, harmonics and the pulsating component etc. Partial discharge (PD) occurring in oil-pressboard insulation is the one of the main causes of insulation breakdown, and it is the main factor of electrical aging of materials. Even though PD characteristics under pure AC or DC voltage waveform have been studied by many researchers, little research has been done with the mixed voltage. In this paper, the AC + DC mixed voltage experiment system is set up to study the PD characteristics under mixed voltage waveforms. The study results indicate that the pressboard withstands most of the DC component and void withstands most of the AC component when applied mixed voltage. For PD inception voltage, it is decided by both the AC component and DC component. For PD development, AC component has more significant influence than DC component. However, the DC component is found to promote PD activity under AC half cycle with the same DC polarity and inhibit PD activity under AC half cycle with the opposite DC polarity. The results in this paper provide an experimental foundation for the converter transformer insulation breakdown mechanism and analysis.

Influence of humidity on current waveform and light emission of a low-frequency discharge controlled by a dielectric barrier

Abstract: The aim of this work is to determine the effect of humidity on a silent discharge in air. A point to plane configuration has been used. Current and emission spectra of the discharge have been recorded in dry and humid air for short and long inter-electrode gaps and with the plane electrode coated by a silicone rubber plate alone or under a polypropylene film. Results show the typical corona discharge regimes. For a long gap, humidity decreases the number of breakdown streamer pulses. For a short gap, the behavior observed depends on the surface conduction of the dielectric in contact with the discharge. These results show that the presence of humidity in the discharge cell not only modifies the gas but also the surface states of the dielectrics coating the electrodes. The surface charge decay appears as a major parameter, since it is related to the local field value which results from the applied field and the reverse field induced by charge accumulation during previous discharges.

Discharges from moving particles in GIS [gas-insulated switchgear]

Abstract: The study of the motion of moving metallic particles in GIS requires a good knowledge of the carried charge of the particle. In this paper, measurements of the charging process of a moving particle, performed in a realistic single-phase GIS, are presented. By measuring the charge impulses and the voltage phase at consecutive impacts, it is possible to estimate the carried charge and then compare the results with the existing models of the particle charge. Also, besides the discharges from in-flight corona reported by several authors, it is shown that, for higher voltage levels, several discharges between the particle and the enclosure (outer electrode) can occur as the particle impacts with the enclosure.

Partial discharge modelling based on a cylindrical model in solid dielectrics

Abstract: Partial discharges (PDs) are harmful to electrical insulation as they may degrade the material. Consequently, a lot of efforts have been made to develop suitable systems for PD measurements and monitoring. Due to the complexity of PDs and many factors that can influence PD characteristics, the research on PDs is still very active and several models have been proposed over the years to understand the behaviours of PDs. In the present paper, we have investigated the frequency characteristics of a cylindrical void in solid dielectric based on the model proposed by Forssen. Using similar program environments of MATLAB and COMSOL, our algorithm performs better in computation time and gives the similar results compared with the experiments. More importantly, a new interface has been developed so users are able to change parameters. This new feature allows the user to examine effects of various factors such as conductivity of the cavity surface, the applied voltage and statistical time lag on PD characteristics.