Partial discharge characteristics of bubble flow under AC non-uniform electric field in FC-72

PurposeHigh voltage direct current (HVDC) cable is an important part in the electric power transmission and distribution systems. However, very little research has been carried out on partial discharge under direct current (DC) conditions. Niemeyer’s model has been widely used under alternating current (AC) conditions. This paper aims to intend to modify the Niemeyer’s model considering both electric field and charge dynamics under DC conditions, and therefore proposes a numerical model describing partial discharge characteristics in HVDC cable. Design/methodology/approachThis paper intends to understand partial discharge characteristics under DC conditions through numerical modelling. Niemeyer’s model that has been widely used under AC conditions has been modified, taking both electric field and charge dynamics under DC conditions into consideration. The effects of loading level or current through the conductor, cavity location and material properties on partial discharges have also been studied. FindingsElectrical conductivity is important in determining the characteristics of partial discharge under DC conditions and discharges tend to happen in short when the cavity field exceeds the inception level under the parameter values studied in the paper. Research limitations/implicationsBuilding the numerical model is the purpose of the paper, and there is lack in experiment and the comparison between the simulation results and experiment. Practical implicationsThe proposed model provides the numerical model describing partial discharge in HVDC cable and helps understand the partial discharge mechanism under DC voltage. Originality/valueTo the best of the author’s knowledge, this paper is a very early research on the numerical modelling work on partial discharge under DC voltage.

Download Full-text

Partial Discharge Imaging Correlated with Phase-Resolved Patterns in Non-Uniform Electric Fields with Various Dielectric Barrier Materials

Energies ◽

10.3390/en13112676 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2676 ◽

Cited By ~ 3

Author(s):

Marek Florkowski ◽

Dariusz Krześniak ◽

Maciej Kuniewski ◽

Paweł Zydroń

Keyword(s):

Electric Field ◽

Optical Imaging ◽

Partial Discharge ◽

Stem Length ◽

Uniform Electric Field ◽

Diagnostic Systems ◽

Streamer Discharge ◽

Dielectric Barrier ◽

Barrier Materials ◽

Discharge Propagation

This paper describes a correlation of partial discharge phase-resolved patterns with an optical imaging performed in a non-uniform electric field configuration. The influence of different dielectric barrier materials, placed on the plane electrode, on the discharge propagation and surface landing was investigated. The investigations were focused on the corona at positive polarity of AC high voltage. It was found that the initial positive corona stage is similar for all cases whereas the discharge propagation and surface landing strongly depends on the barrier material properties. The observed streamer discharge modes have been described by the geometrical measures such as stem length, stretch of a discharge profile on the dielectric barrier surface and an hemispherical envelope of discharge filaments. Since various dielectrics reveal different properties of charge accumulation and surface neutralization, the charge memory effect may be visible and can be related to the ability to create and sustain of additional electric field component. It may refer to subsequent discharges as well as to conditions faced at the voltage polarity reversal. The correspondence between different forms of phase-resolved patterns have been associated with the modes of streamer discharges observed by optical imaging. Presented methodology poses huge potential for both scientific investigations on underlying discharge phenomena as well as on the application in future diagnostic systems of HV insulation.

Download Full-text

Using the Method of Harmonic Distortion Analysis in Partial Discharge Assessment in Mineral Oil in a Non-Uniform Electric Field

Energies ◽

10.3390/en13184830 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4830

Author(s):

Alper Aydogan ◽

Fatih Atalar ◽

Aysel Ersoy Yilmaz ◽

Pawel Rozga

Keyword(s):

Electric Field ◽

Leakage Current ◽

High Voltage ◽

Partial Discharge ◽

Harmonic Distortion ◽

Mineral Oil ◽

Significant Rise ◽

Partial Discharges ◽

Uniform Electric Field ◽

Different Diameters

In high-voltage equipment, it is vital to detect any failure in advance. To do this, a determination of the partial discharges occurring at different voltage types as well as at different electrode configurations is essential for observing the oil condition. In this study, an experimental setup consisting of a needle–semi-sphere electrode configuration immersed in mineral oil is prepared for laboratory experiment. In such a way, a non-uniform electric field is created and the leakage currents are monitored from the grounded electrode. A total of six different electrode configurations are analyzed during the tests by the use of hemispheres of different diameters as grounded electrodes and copper and steel pointed (medical) needle high-voltage electrodes. In the experiments, the partial discharges occurring at four different voltage levels between 5.4 and 10.8 kV are measured and recorded. The effect of the different electrode configurations and voltage levels on the harmonic distortion are noted and discussed. It is experimentally confirmed that it is possible to measure the leakage current caused by the partial discharges of the corona type in oil at the different metal points, creating high-voltage electrodes and different electric field distributions based on the proposed non-invasive measurement technique. The studies showed that there is a significant rise of even harmonic components in the leakage current during the increase in the partial discharge intensity with the 5th harmonic as dominant.

Download Full-text