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Partial Discharge Pulse Propagation in Coaxial Cable
(2022-01-01)
Juntasorn, T.
;
Chancharoensook, P.
;
Pattanadech, N.
In the past, Coaxial cable was the signal cable used to transfer computer data. However, coaxial cables are now being modified for use in the high voltage coaxial cables to increase the security of power transmission in various areas. In addition to increased security, there is also an issue of stability maintenance and many perspectives as well. Because the cable that used to be utilized is still insulated. Therefore, Partial Discharge (PD) can still happen in the electrical system. This paper presents the PD propagation within the coaxial cable simulated via PSCAD/EMTDC program and carried out with RG-58 coaxial cable in a laboratory by testing the propagation of the PD pulse according to the conditions of different cable distances. From the experiment, the calculations will be reversed by considering on the differences of the time manner that PD pulse flows on the cable. The time reference point that the research studied has 2 points which are Peak to peak and Time of arrival(TOA). The comparison between simulation and experiment indicated the similar results with slight discrepancies caused by factors that can be accepted. TOA has smaller errors comparing with the peak to peak point showing that PD pulse flowing on the cable is attenuation and dispersion to the tailing wave part. That's the reason using Peak to Peak is a time reference point that has more errors. A thorough study of PD propagation is useful for in-depth analysis to locate the PD source accurately. As a result, the defect will be resolved on the spot.
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Frequency Domain Spectroscopy of Pressboard Impregnated with Natural Ester under Thermal Stress
(2022-01-01)
Chumpiboon, K.
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Vittayakorn, W.
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Kittikhuntharadol, Y.
;
Maneerot, S.
;
Pattanadech, N.
One of the most popular insulating liquids is mineral oil, which is used in many high-voltage apparatuses, especially in transformers. For a few decades, the concept of the use of alternative insulating liquids has been presented. Natural ester is a vegetable-based insulating liquid. Pressboard is a type of electrical insulation paper made of cellulose. Frequency Domain Spectroscopy (FDS) has been used to assess the insulation characteristics such as oil-impregnated paper. In this paper, the FDS of pressboard impregnated with natural ester under thermal stress and pressboard impregnated with natural ester were studied. In the experiment, the pressboard test specimens were heated at 100 degrees Celsius in a vacuum oven for 48 hours to reduce the moisture. Then, the test specimens were impregnated with natural ester for 0, 8, 16, and 24 hours. After that, they were simulated with thermal stress by heating at 150 degrees Celsius in a vacuum oven for 0, 30, and 90 days. To analyze their dielectric integrity, FDS was performed by DIRANA. The test cell for solid insulation testing, according to JIS C2111 was prepared and used for the FDS experiment. The result shows that the characteristics of the natural ester-impregnated pressboard that had been subjected to thermal stress were slightly different when compared with the same impregnation time of the pressboard.
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The Effects of Coupling and Grounding on the Partial Discharge Pulse Propagation in the Underground Cable
(2022-01-01)
Rojanasunan, W.
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Chancharoensook, P.
;
Jeenmuang, S.
;
Mongkolsatitpong, S.
;
Pattanadech, N.
When a Partial Discharge (PD) pulse propagates through a cross-bonded (CB) power cable system, such pulse undergoes attenuation and dispersion along a cable. Moreover, the coupling effect occurs when a PD pulse propagates in HV cable joints and CB link lines. This paper aims to study the effects of coupling phenomena and groundings on the PD pulse propagation. The experiments were divided into 3 parts: the experiment for attenuation in the conductor and ground wire, the experiment for coupling effect, and the experiment for different grounding configuration. The experimental setups used a 30 m length of new 33 kV XLPE insulated cable. PD pulses was obtained from a PD calibrator, and the pulses are detected by Radio Frequency Current Transformer at various positions. The knowledge gained from this research should be useful for a deep understanding of pulse propagation and PD source localization in CB power cable systems.
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A locating diagnosis of partial discharge on cross-bonding ground system
(2021-05-19)
Inwanna, W.
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Mongkolsatitpong, S.
;
Chancharoensook, P.
;
Pattanadech, N.
At the present, Thailand has turned the attention to Underground Cable (UC) systems and trends to use it more to safety, stability and reliability of electrical system. However, one problem that can affect to this electrical system is the Partial Discharge (PD) problem. Most of PD problems are caused by incomplete installation, maintenance reason and insulation degradation on the weakest part, especially cable joint. This paper proposes a method of analysis to locate the PD source in UC systems with Cross Bonding (CB) focus on cable joints. This work has carried out in laboratory on CB system model using 50ohm R58 coaxial cable instead of underground cable. The PD detection technique according to IEEE 400.3 standard with a RFCT sensor to refer the appropriate signal. This work uses a PD diagnostic device that can filter noise from the PD groups and separate groups of PD for greater analysis accuracy. To determine which cable joint is PD source and to be able to fix it on the spot. The PD signal analysis are performed by using time of arrival method considered together with the characteristics and the polarity of the PD pulse.
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Applications of Ozone for Recycling of Wastewater from Biogas Production for Electricity Generation
(2018-08-21)
Tantirungruang, W.
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Chancharoensook, P.
;
Yutthagowith, P.
This paper presents applications of ozone to recycle the wastewater from the biogas production process for electricity generation. The ozone could be generated by using electric field between polarized electrodes. In comparative experiments, three tanks were used for biogas fermentation using anaerobic microorganisms. We designed three different experimental settings as follows: 1) The one using only fresh wastewater from ethanol production process. 2) The one using recycled wastewater with ozonation. 3) The one using recycled wastewater without ozonation. The experimental results indicated that ozone could help improving the biogas production to 2.1 liters/day per 1 liter of recycled wastewater. The methane and carbon dioxide concentrations were 66. 8% and 38. 5%, respectively.
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Efficiency improvement of converter for switched reluctance motor drives at low speed operation
(2009-12-01)
Woothipatanapan, S.
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Chancharoensook, P.
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Jangwanitlert, A.
This paper presents a method to improve the efficiency of a standard asymmetric half-bridge converter for 3 phase, 12/8 switched reluctance motor (SRM) drives at low speed operation. At that speed range, the SRM converter operates mainly in current chopping modes either hard chopping or soft chopping control. This work emphasizes on minimizing the main power losses during the turn-off interval of each cycle. Once the optimum size of snubber capacitor is obtained from calculation, such snubber capacitors are paralleled with chopping switches in order to reduce rate of voltage rise across those switches and ultimately their switching losses can be decreased. The developed dynamic model based on measured data of flux linkage and static torque characteristics of the SRM has been used for simulation in MATLAB/Simulink environment. The results have satisfactorily verified the validity of the proposed concept.

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