Kunakorn, Anantawat

Preferred name

Kunakorn, Anantawat

Alternative Name

Kunakorn, A.

Kunakorn, Anatawat

Main Affiliation

School of Engineering

anantawat.ku@kmitl.ac.th

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Polarization and depolarization current characteristics of thermally stressed stator bars
(2019-07-01)
Pattanadech, N.
;
Srichuen, N.
;
Wang, C.
;
Kaewdee, N.
;
Poungpat, T.
Polarization and depolarization current (PDC) measurement was used in this research to investigate the insulation integrity of stator bars. This method is non-destructive testing. This paper presents the PDC analysis of thermally stressed stator bars divided into two main groups. The first group was heated at 100^{\circ}C and the second group was heated at 130 ^{\circ}C for 36 hours. After 12, 24 and 36 hours of heating process, PDC measurement of each test specimen was performed. PDC test results including capacitance ratio and dielectric dissipation factor were analyzed and reported.
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Computer aided-program for validation of measuring system from unit step response by time convolution method
(2005-01-01)
Yutthagowith, P.
;
Pattanadech, N.
;
Kunakorn, A.
;
Phoomvuthisarn, S.
This paper presents the design and development of the computer algorithm based on LabVIEW for verification of a high voltage measuring system. The algorithm consists of two parts. The first part is a program for calculating the parameters of unit step responses which are verified an ability of the measuring system by a comparison with the values given in IEC 60060-2. The second part is a program for calculating the output voltage waveform by time convolutions between standard testing waveforms and unit step responses. The standard waveforms under investigation are full lightning impulse voltage waveforms, tail-chopped lightning impulse voltage waveforms, front-chopped lightning impulse voltage waveforms and steep-front voltage waveforms according to IEC standards 60060-2 and 61211. This paper considers two different types of the measuring systems, with a resistive voltage divider and a damped capacitive voltage divider for testings. The results show that the algorithm proposed in this paper is practicable, and should be a useful tool for impulse voltage measurements in a standard high voltage laboratory.
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Implementation of fuzzy logic controller with bifurcation control of a current-mode boost converter
(2007-12-01)
Khaehintung, Noppadol
;
Sirisuk, Phaophak
;
Kunakorn, Anantawat
This paper presents the design of a basic fuzzy logic controller for switching current-mode DC/DC boost converters. The proposed simple fuzzy logic controllers used only nine rules to regulate output voltage. Moreover, they provide an optimal slope compensation to keep the system adequately remote from the first bifurcation point by mean of stabilizing around the reference signal. In spite of nonlinear characteristics and instabilities of the converter, the performance of the closed-loop control system can be considerably improved to avoid bifurcation phenomena. The experimental results found that these technique introduced in this paper give satisfactory results with the regulating and tracking modes under changes in operating conditions. © 2007 IEEE.
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Estimation of short circuit current due to a group of induction motors using an aggregation model
(2004-12-01)
Suwanwej, Wanlop
;
Kunakorn, Anantawat
This paper presents generalized equations for determining an aggregation model to represent a group of induction motors connected in the same bus of industrial power systems. The model is employed in calculating short circuit current contribution with different types of faults from the group of induction motors. The simulation and analysis are performed using PSCAD/EMTDC. Various case studies are used to implement the model. It is found that the aggregation model proposed in the paper can give reasonable and satisfactory results for short circuit contribution due to the induction motor loads. © 2004 IEEE.
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Transient equivalent circuit of a horizontal grounding electrode
(2012-12-31)
Yutthagowith, P.
;
Kunakorn, A.
;
Potivejkul, S.
;
Chaisiri, P.
This paper proposes an equivalent circuit of grounding electrode which has validity upto a frequency range of sub-sequence stroke lightning current. The equivalent circuit is modelled by lumped and distributed parameters based on quasistatic assumption. In this study, only a grounding electrode installed horizontally is in consideration. The limitation of the uniform distributed equivalent circuit of a grounding electrode is presented. The non-uniform distributed equivalent circuit is proposed. The proposed equivalent circuits are verified by comparison of the results of ground potential rise computed by the proposed circuit, the partial element equivalent circuit method, and available experimental data. The proposed equivalent circuit can be adapted for being the models for development and design of the grounding system for lightning protection system in transmission and distribution systems in an effective way. © 2012 IEEE.
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A cable terminator for partial discharge and dielectric loss measurements
(2001-12-01)
Nakaviwat, K.
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Kumpiranont, S.
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Boonseng, C.
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Apiratikul, P.
;
Kunakorn, A.
This paper presents a design of the cable connector used in partial discharge and dielectric loss tests. The body of the connector is constructed using the acrylic tube and PVC, and the oil is used as an insulating medium. In order to implement the connector, partial discharges and the dielectric loss (tan δ) of a cable are tested according to IEC standards. It is found that the cable connector proposed can give the satisfactory and reasonably accurate results from the measurements. In addition, the cost of the construction of the connector developed is cheaper than that of the commercial module.
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Robust pitch controller design in hybrid wind-diesel power generation system
(2008-09-23)
Cuk Supriyadi, A. N.
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Ngamroo, I.
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Kaitwanidvilai, S.
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Kunakorn, A.
;
Hashiguchi, T.
In this paper, the robust control design of pitch controller for frequency control in a hybrid wind-diesel power generation system is proposed. The structure of the pitch controller is a 1<sup>st</sup>-order lead-lag compensator. To take system uncertainties into account, the coprime factorization is applied in system modeling. To obtain the controller parameters, the performance and stability conditions of H<inf>∞</inf> loop shaping technique are used to formulate the optimization problem. The genetic algorithm is employed to solve the problem. Simulation studies show the frequency control effect and robustness of the proposed controller against system uncertainties in comparison with a variable structure pitch control. ©2008 IEEE.
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The Study of Polarization and Depolarization Current Measurements on Service-Aged 22 kV XLPE Underground Cables with Presence of Water Trees
(2022-01-01)
Udomluksananon, P.
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Kunakorn, A.
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Maneerot, S.
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Bunlaksananusorn, C.
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Pannil, P.
This paper represents the condition assessment of service-aged 22 kV XLPE insulated underground cables. From the investigation, the water trees were detected in the insulation layer. The visual inspection of underground cables reveals the presence of copper carbonate contaminated on the copper tape layer. Some underground cables have the discontinuity of the copper tape layer. To evaluate the insulation condition of the underground cables, the polarization and depolarization current (PDC) measurements were performed on both the service-aged and the new (or unused) cables. The underground cables to experiment with the length of insulation screen equal to 1 m were prepared. In this research, the PDC measurements were performed on different aspects, i.e., the testing voltages (600 V, 800 V, and 1000 V), the testing positions, the effect of the discontinuity of the copper tape layer which occurred during service, the influence of the presence of copper carbonate, and the influence of water trees in XLPE cables. The dielectric response of the underground cables by using polarization and depolarization current measurements can diagnose the problems in service-aged underground cables, but this paper needs more test data for accurate interpretation.
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Studies of Electrical and Thermal Characteristics of Natural Ester Immersed Transformer Compared with Mineral Oil Immersed and Palm Oil Immersed Transformer
(2018-11-14)
Maneerot, S.
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Jariyanurat, K.
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Nimsanong, P.
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Bunlaksananusor, C.
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Kunakorn, A.
This paper represents studies of electrical and thermal characteristics of natural ester immersed transformer compared with mineral oil immersed and palm oil immersed transformer by designing and constructing three single-phase transformers with rated 400/1000V 10kVA, the first transformer used mineral oil, the second transformer used natural ester, and the last one used palm oil, for studying about electrical properties, thermal properties and chemical properties under different types of liquid insulation in each transformer. First of all, three types of liquid insulation were tested with many item such as dielectric breakdown strength according to IEC 60156, dielectric dissipation factor following to ASTM D924-99. Besides, dielectric breakdown strength of impregnated pressboard were also investigated following to IEC 60243-1. Moreover, the chemical properties of the insulations were tested for some properties such as moisture content in accordance with ASTM D1533-00, interfacial tension according to ASTM D0971-99, acidity according to ASTM D974-02. After that, transformers were operated at 100 % of designed rated with inductor load for four months by which the temperature, current, and voltage were recorded every hour. Every two months, the liquid insulation was sampling from each transformer to be investigated. From the test results, they can concluded that natural ester are the alternative liquid insulation for using instead of mineral oil. In part of palm oil, it has good properties but it has the weak points about dielectric dissipation factor and acidity which are higher than the others.
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Frequency dependence parameter analysis of underground cables with and without joint
(2018-06-29)
Nimsanong, P.
;
Kunakorn, A.
;
Pattanadech, N.
This paper represents the dielectric investigation of XLPE power cables with and without cable joint (premolded joint) by using polarization and depolarization current (PDC) measurement. To investigate the polarization phenomena of the underground cable (case 1) and the underground cable with the premolded joint (case 2), the XLPE cables with the cross-section area of 240 mm<sup>2</sup> and 5 m long with rate voltage of 12/20(24) kV with and without premolded joint were used in the experiment. In this research work, the DC voltage of 1,000V was applied to insulation system for measuring polarization current, i<inf>pol</inf>(t). Then, suddenly disconnected the DC applied voltage source to short circuit the tested cable to measure depolarization current, i<inf>dep</inf>(t), In case 1, the PDC measurement was only for 100 seconds due to its homogeneous insulation of XLPE cable; only conduction current and interfacial polarization current with short relaxation time existed. In case 2, the PDC measurement was done for 2,000 seconds. In this case the polarization current was from XLPE cable mentioned and the interfacial polarization current from the barrier between XLPE cable and cable joint. From the experiment, the frequency dependence of the complex capacitance and dielectric dissipation factor of the underground cable and the underground cable with the premolded joint were analyzed. It is found that the trend of real part of the complex capacitance and the conduction loss of both case studies is not much different. However, the trend of imaginary part of the complex capacitance and polarization loss of both case studies is clearly different. Two peaks of imaginary parts of complex capacitance and polarization loss of the underground cable with joint is from XLPE and the junction of XLPE and joint.

Kunakorn, Anantawat

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