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Author: search.filters.author.Yutthagowith, P.Subject: search.filters.subject.partial discharge

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    A partial discharge testing system based on a 5-level converter with different control signals
    (2018-11-01)
    Yomkaew, N.
    ;
    Marukatat, N.
    ;
    Yutthagowith, P.
    In this paper, analyses of a partial discharge (PD) testing systems using a voltage source from a 5-level converter with different control signals are presented. The low voltage source with 200 Hz of the test system is generated using the 5-level converter. The converter connected to a high voltage transformer, a partial discharge detection. The LC-filter type is set for the test system. The efficiency of voltage source from the 5-level converter with different control signal topologies, i.e. 5-level square wave, 5-level quasi-square wave, and 5-level sinusoidal pulse width modulation (SPWM) with modulation index (m<inf>a</inf>) of 1.0. The effect of the topologies to partial discharge test system is presented and compared in cases of the voltage difference, total harmonic distortion (THD<inf>v</inf>) of the output voltage, and the background noises in the partial discharge testing system with no-load and load test with a potential transformer (PT). It is found that the 5-level sinusoidal pulse width modulation (SPWM) with modulation index 1.0 provides the best performance in cases of the voltage difference and THD<inf>v</inf> of below 5%, and the background noise of below 2.5 pC.
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    Development of a low-pass filter for partial discharge testing system with the power frequency converter
    (2018-11-01)
    Prombud, T.
    ;
    Kitcharoen, P.
    ;
    Yutthagowith, P.
    The development of a low-pass filter for partial discharge test system that based on a power frequency converter is presented in this paper. The PD testing system is composed a 200-Hz power frequency converter and the designed filter connected with a high-voltage test transformer and a conventional partial discharge detection system. It is found that the power frequency converter acting as the low-voltage source always provides the high noise level with effecting to the background noise occur in the partial discharge test. Sometimes noise level is higher than the acceptable level of the PD tests in some high-voltage equipment such as potential transformers, distribution transformer, and so on. In this paper, the performances of the filters with different designs are studied and compared the result in terms of the output voltage difference (RMS, voltage , and ,peak,voltage 2), total harmonic distortion of the output high voltages value (THD<inf>v</inf>), and value of background noises as occur in the partial discharge test. The low-voltage source based on uni-polar pulse width modulation (PWM) topology was employed in the PD testing system. From the experimental results, the designed filter shows the promising performances with low levels of the background noise, THD<inf>v</inf>, and voltage difference. The experimental results show that the background noise is lower than 2.0 pC, the voltage difference and THD<inf>v</inf> are less than 5%. In addition, the designed filter has been tested in the partial test of a real potential transformer successfully.
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    Development of a resonant frequency converter for partial discharge tests on potential transformers
    (2018-06-08)
    Yutthagowith, P.
    ;
    Prombud, T.
    ;
    Leelachariyakul, B.
    In this paper, the development of a partial discharge testing system based on a resonant frequency converter for potential transformers (PTs) is presented. The system is composed of a power low-voltage variable frequency converter connected with a frequency tuning circuit, a high-voltage testing transformer, and a conventional partial discharge detection system. The performances of the developed system in comparison with the conventional PWM frequency converter were investigated terms of the quality of the output voltage from the high-voltage testing transformer, i.e. the voltage difference (peak voltage/square root of 2 and rms voltage), total harmonic distortion of the output high voltages (THDv), and background noises in the partial discharge test. It is found that the developed system based on the resonant frequency converter provides the better performances (in terms of the output voltage from a testing transformer, the voltage difference, THDv, and background noise) than those of the PWM converter. The voltage difference and THDv are lower than 2%, and the background noise is less than 2.5 pC. In addition, the developed system has been used for the real partial test on a potential transformer in the distribution system successfully. The developed inverter is an attractive choice in the PD tests of potential transformers.