Charge Accumulation at High DC Voltage and Superimposed Medium Frequency AC Voltage

Seifert, Florian; Porizka, I.; Leu, Carsten

doi:10.1109/icd46958.2020.9341963

Cited by 5 publications

(2 citation statements)

References 7 publications

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“…However it is possible that the PD activity declines with the time as a result of the applied high DC field and consequently space charge phenomena as shown in [6]. More space charges are generated with mixed voltage stress than with pure DC stress [11,12,16] and their accumulation at interfaces such as the mica tape layers between the impregnation resin can eventually lead to the distortion of the electrical field. It is hence possible that the PD activity within the insulation changes with time, which was not investigated in this contribution.…”

Section: Discussionmentioning

confidence: 99%

Partial Discharge Behavior of Epoxy-Mica Insulation System under Superimposed AC and DC Voltage Stress

Linde

Backhaus²,

Schlegel³

et al. 2022

NORD-IS

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Recent technology advances in wind energy conversion systems include a new type of permanent magnet synchronous generator with a segmented stator that allows lightweight concepts with high efficiency and superior controllability. Each stator segment is driven by a separate power converter. The various cascaded power converters can be connected in series and in parallel, which ultimately leads to the superposition of a DC and an AC voltage stress in the insulation of the stator coils. The resulting DC-AC mixed voltage is an entirely new electrical stress for the epoxy-mica insulation system that is typically utilized as main insulation of rotating electrical machines. In order to resemble this stress, typical dielectric tests such as partial discharge (PD) measurements and long-term aging of model insulation systems have to be be carried out under DC-AC mixed voltage stress. The mentioned investigations are presented in this contribution. The results indicate that the AC voltage is dominant with regard to the PD inception and influences the PD parameters such as the apparent charge and the repetition rate substantially when compared to the DC voltage proportion. The accelerated aging tests with significantly higher AC-DC mixed voltage stress than is expectable under operating conditions revealed no measurable PD deterioration of the investigated insulation systems.

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Section: Discussionmentioning

confidence: 99%

Partial Discharge Behavior of Epoxy-Mica Insulation System under Superimposed AC and DC Voltage Stress

Linde

Backhaus²,

Schlegel³

et al. 2022

NORD-IS

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show abstract

“…In this application, two different voltages are superposed and composite voltage is applied to test objects by a single point [4]. In recent years, many studies have been carried out on insulation performance investigations under composite or combined voltages [5][6][7][8][9]. However, these studies are much less compared to studies performed for a single voltage type (only AC, only DC or only impulse voltage), so there is a gap in the literature on this subject due to laboratory facilities, the application of different voltage types at the same time and the difficulties of the protection elements.…”

Section: Introductionmentioning

confidence: 99%

Investigation of impact of DC component on breakdown characteristics for different electric fields under composite AC & DC voltage

et al. 2022

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The valve side of the converter in the high-voltage direct current is subjected to mixed voltages such as composite AC & DC voltage. In this study, the effects of the homogeneity of electric field on breakdown voltage were investigated for different �DC component amplitudes of the composite voltage. The field efficiency factor was calculated using mean and maximum field strengths for all of them. Variation of breakdown voltage of air was examined under the composite AC & DC voltage for different ratios �DC. As one result of the study, the breakdown occurs at the positive half-wave of the AC voltage despite −DC voltage being applied due to positive corona discharge pulses. This breakdown point is named as the polarity change point. The breakdown voltage increases with the decrease of DC voltage component up to polarity change point in nonuniform electric field. In less uniform electric field, the AC breakdown voltage was measured slightly higher than the DC breakdown voltage. In less uniform electric field, as the ratio of the applied AC voltage to DC voltage increases, the breakdown voltage gradually approaches the AC breakdown voltage. This result is similar to the result obtained for the +DC component in non-uniform electric field experiments.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Electric field analysis of 66 kV and 110 kV SiR insulators under combined AC–DC voltages

2022

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Charge Accumulation at High DC Voltage and Superimposed Medium Frequency AC Voltage

Cited by 5 publications

References 7 publications

Partial Discharge Behavior of Epoxy-Mica Insulation System under Superimposed AC and DC Voltage Stress

Partial Discharge Behavior of Epoxy-Mica Insulation System under Superimposed AC and DC Voltage Stress

Investigation of impact of DC component on breakdown characteristics for different electric fields under composite AC & DC voltage

Electric field analysis of 66 kV and 110 kV SiR insulators under combined AC–DC voltages

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