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The Effect of Surface Leakage Current on Frequency Domain Spectroscopy of 22 kV OIP Bushing
(2024-01-01)
Rojanasunan, Warisanan
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Chumpiboon, Komin
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Udomluksananon, Patt
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Jeenmuang, Siwakorn
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Chancharoensook, Phop
In this paper the dielectric response in frequency domain or frequency domain spectroscopy (FDS) is used to assess the effect of surface leakage current both from high voltage side and ground side on the FDS results of OIP bushings. The test object in this paper is a 22 kV OIP bushing which is out of service. The surface leakage current can be simulated using the copper tape as a bandage around the bushing core in several locations. From the FDS results, several parameters i.e., dissipation factor, capacitance, and capacitance ratio together with frequency scanning of capacitance and dissipation factor from many cases were investigated to get the fundamental knowledge of how to interpret the FDS result of OIP bushing.
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Control of a 3-Phase 12/8 Switched Reluctance Generator for Future Energy System Applications
(2024-01-01)
Chancharoensook, Phop
This paper presents implementation of a control system for a 3-phase 12/8 switched reluctance generator (SRG). The study has confirmed the potential of switched reluctance machines to be decent alternatives in renewable energy applications, energy storage systems and electrified transportation systems. Initially, a dynamic model of the SRG was created in MATLAB/Simulink environment to achieve useful preliminary results from computer simulation. Next, in hardware realization, the proposed system employed a standard asymmetric half-bridge (AHB) converter to generate a voltage of 200 V at the DC-link. Optimal turn-on and turn-off angles of phase current waveforms were used through commutation signals generated by a simple and inexpensive opto-interrupter rotor position sensor. There were two closed-loop controls involved in the system. The outer loop was for DC-link voltage control using PI controller while the inner loop was for phase current control using soft chopping hysteresis control technique. Finally, real-time control was implemented using an economical dsPIC30F4011 microcontroller. Experimental results have shown acceptable performance of the proposed SRG control system in various conditions, including normal operation, speed change and step reference voltage change. The DC-link voltage can be satisfactorily regulated when subjected to those conditions.
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Analysis of electrical insulation paper by Simulation for analyze Polarization and Depolarization current testing method
(2023-01-01)
Rakkaphan, Chananut
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Boonsaner, Nutthaphan
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Pattanadech, Norasage
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Chancharoensook, Phop
This paper presents the quality analysis of insulation paper in distribution transformer oil in Thailand. The country locates in tropical zone and therefore experiences relatively high temperature. Analytical principles based on polarization and depolarization current method with various test conditions are used. Computer simulation can help to analyze the efficiency of insulation paper in transformer oil under different voltages and temperatures. The tested system consists of an electrode inside a high-Temperature and high-voltage control cabinet. It can be concluded that increasing temperature has a marginal effect on the electric field stress of the electrode. However, the rising temperature significantly affects the polarization current that flows through the insulators. The results can indicate the limitation of using oil insulation paper and how to improve the quality of it.
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Frequency Domain Spectroscopy Analysis of the Water Tree XLPE Cable
(2022-01-01)
Sawatdimongkol, Whichakorn
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Chancharoensook, Phop
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Sawatdimongkol, Worachai
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Taylim, Alisala
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Luangpol, Amata
Water tree is one type of insulation deterioration occurring in polymeric cables such as polyethylene, ethylene-propylene rubber, and cross-linked polyethylene (XLPE) caused by the existing impurities in the bulk insulation or imperfection of the semiconductive surface. Moreover, the water tree phenomenon affects the cable's overall lifetime and can be developed into an electrical tree, leading to the failure of the cable. Because of this, the evaluation of water trees becomes one of the most important factors in the condition assessment of the cable. This paper presents the comparison of the dielectric properties of 22 kV XLPE underground cable between aged and new (unused) cables. Furthermore, the water tree was detected in the aged cable. Besides, the evaluation of aged and new cables was performed by frequency-domain spectroscopy (FDS), which measures the insulation's complex capacitance and dissipation factors in the frequency domain. Then, the aged and new cables' complex capacitance and dissipation factor were compared. The test result found that the dissipation factor and imaginary part of the complex capacitance of the aged cable have a higher value than these of the new cable. More or less, the results show that FDS is one of the non-destructive testing methods suitable for assessing the condition of the cable insulation, which deteriorated by water tree.
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The Study and Analysis of Oil-immersed Power Transformer by Using Artificial Neural Network for Designing Program Apply in the Industry of Testing Oil-immersed Transformers
(2020-10-25)
Boonsaner, Nutthaphan
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Chancharoensook, Phop
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Bunnag, Chisanucha
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Suwantaweesuk, Achirawit
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Vongphanich, Kiattisak
This research presents the study and analysis of faults in the oil-immersed transformer. Abnormalities can be analyzed from the Dissolved Gas Analysis (DGA) test. The oil has a variety of compounds such as hydrocarbons, oxygen, nitrogen and hydrogen. The amount of gas in oil has distinctive characteristics that can indicate abnormalities in different types. This program is developed based on according to standard IEEE Std C57.104TM - 2019. This program is designed to detect for defects in oil-immersed transformers by using artificial neural networks (Artificial Neural Network: ANN). The program using MATLAB programs is prepared for maintenance planning and supports applications from basic learning to industrial sector.
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Test Chamber Designed with Temperature Control for Partial Discharge and Polarization and Depolarization Current Testing
(2020-10-25)
Boonsaner, Nutthaphan
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Panoon, Nitouch
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Chancharoensook, Phop
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Pattanadech, Norasage
This paper presents the temperature-controlled test chamber for Partial Discharge and Polarization and Depolarization Current test of dielectric liquid including impregnated pressboards with the various conditions. Besides, the temperature of the test specimen is controlled between room temperature to 300°C. The temperature distribution in the test chamber was simulated. Besides, the electric field stress at the electrodes were simulated. Furthermore, different kinds of sensors such as a thermocouple, gas sensors, and so on were designed to be equipped within the test chamber. From the simulated result, both electric field stress and temperature distribution were in the given conditions.
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Dielectric Loss Factor Measurement in A Gas-Insulated Transmission Line by Using Very Low Frequency Test
(2020-06-01)
Nganpitak, Tritod
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Rugthaicharoencheep, Nattachote
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Chancharoensook, Phop
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Pattanadech, Norasage
Very low frequency tan delta measurement (VLF-TD measurement) is one of the insulation diagnosis methods usually uses to diagnosis the condition of electrical cable insulation. However, this research focuses on using VLF-TD measurement with a gas-insulated transmission line (GIL). The 230kV, 2500A, single phase, GIL with 2.0 m length was installed and prepared for experiments. in this paper, VLF-TD experiments were divided into 5 cases, classified by using types of artificial defects as a criterion, i.e. 1) The clean GIL without any defect, 2) The GIL with scratched on the surface of cone insulator, 3) The GIL with tracking path on the surface of cone insulator, 4) The GIL with protrusion on high voltage conductor and 5) The GIL with protrusion on enclosure. The average tan delta, VLF tan delta stability, and VLF differential tan delta were presented and compared in this paper.
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Dielectric response analysis for cable joint problems in medium voltage underground cable system
(2020-01-01)
Klienhom, Sitthisak
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Boonsaner, Nutthaphan
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Nimsanong, Phethai
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Chancharoensook, Phop
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Kunakorn, Anantawat
This paper represents the investigation of dielectric response analysis of a cable system composed of a medium voltage XLPE underground cable, a heat-shrink cable joint and a heat-shrink cable termination. A 12/20(24) kV single core XLPE underground cable with the nominal cross-section area of 240 mm<sup>2</sup>, three pieces of 22 kV cable joints, and eight pieces of 22 kV cable termination were prepared for the experiment. Then, polarization and depolarization current (PDCs) measurement were performed. The experiments were divided into two parts. The first part was composed series of three tests, A — C, and the second part consisted series of two tests, D — E, as follows: Test A examined dielectric response of a 6 m healthy XLPE underground cable, Test B examined dielectric response of a 6 m healthy XLPE underground cable with two healthy cable terminations, Test C examined dielectric response of a two of 3 m healthy XLPE underground cable with healthy cable terminations connected by a healthy cable joint, Test D used the test object similarly as case C but the cable joint was contaminated with copper particles, and Test E used the test object similarly as case C but the cable joint was contaminated with tiny pieces of water blocking. From the experiment, the PDCs and the derived dielectric parameters such as geometrical capacitance, insulation resistance, polarization index, depolarization index, charge difference curve and charge ratio curve were analyzed. The PDCs and the derived parameters were found different for each case of study as details in this paper. Besides, the charge ratio proposed by authors is a valuable parameter for the diagnosis of insulation system of high voltage equipment.
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Polarization and Depolarization Current Measurement for Foreign Object Detection in Gas-Insulated Transmission Line
(2019-10-01)
Nganpitak, Tritod
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Chancharoensook, Phop
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Pattanadech, Norasage
Polarization and depolarization current (PDC) test is one of non-destructive insulation test method that usually uses for diagnosis the solid and liquid insulation problems. In case of gas-insulated transmission line (GIL), it not only comprises of gas insulation but also the solid insulation such as cone insulators. This paper presents the PDC measurement for foreign object detection in GIL. A 230kV, 2500A, single phase GIL with 2 m length was used in the PDC experiments. The external diameter of this GIL conductor and enclosure are 92 and 366 mm respectively. In the experiment, defects on the cone insulator was simulated in three cases, i.e. 1) cone insulator was attached with a paper tape, 2) cone insulator was attached with an aluminum foil, 3) cone insulator was attached with a moist paper. The width of the simulation defect was approximately 2 mm. The lengths of the simulation defects were varied from 25 - 200 mm depending on defect types. PDC test results obtained from the GIL with the simulated defect cone insulators were compared with that of clean and dry cone insulator as reference. The results of the experiments showed that PDC curves obtained from GIL with the simulated defect cone insulators were clearly different from that of the reference case. Other analyses are reported in the paper.
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An improved asymmetric half-bridge converter for switched reluctance motor in low-speed operation with current regulated mode
(2015-10-01)
Woothipatanapan, Sakhon
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Chancharoensook, Phop
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Jangwanitlert, Anuwat
This study presents a novel method for reducing the switching losses of an asymmetric half-bridge converter for a three-phase, 12/8 switched reluctance motor operated in low speed. In particular, this study aims to reduce the switching-off losses of chopping switches in the converter when operated in the current regulated mode (chopping mode). The proposed method uses the mixed parallel operation of IGBT (chopping switch) and MOSFET (auxiliary switch). MOSFET is precisely controlled to momentarily conduct prior to the turn-off interval of the IGBT. Consequently, the voltage across the switches is clamped to approximately zero, substantially decreasing the turn-off switching losses. The analytical expressions of power losses are extensively elaborated. Compared with the conventional asymmetric half-bridge converter, the modified converter can effectively minimize the switching losses. Therefore, the efficiency of the converter is eventually improved. Computer simulation and experimental results confirm the effectiveness of the proposed technique.

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