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Access type: UnknownAuthor: search.filters.author.Limcharoen, Worrakan

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    Multilevel frequency converters and noise reduction for pratial discharge tests
    (2017-11-03)
    Kitcharoen, Phattarin
    ;
    Kunakorn, Anantawat
    ;
    Yutthagowith, Peerawut
    ;
    Limcharoen, Worrakan
    This paper presents the usage of multilevel frequency converters for partial discharge tests and an approach for noise reduction. The comparison of the background noise generated by square wave (2-level) and 5-level frequency converters with the frequency of 200 Hz is presented. The testing frequency of 200 Hz is necessary for partial discharge test of transformers because of avoiding saturation effect of the iron core. Therefore, the frequency converter must be generated the voltage with the frequency of more than two time of the power frequency. The comparison of background noise and output voltage waveform generated by the developed converters is presented. Both frequency converters with the noise reduction technique (applied a low pass filter) have very low background noise, and the generated voltages are closed to pure sinusoidal waveform when the frequency converters supply to PD test circuit.
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    Solid state tesla transformer for flashover test on suspension insulators
    (2017-10-27)
    Pongsathit, Watchara
    ;
    Yutthagowith, Peerawut
    ;
    Limcharoen, Worrakan
    This paper presents design and construction of a dual resonant solid-state Tesla transformer (DRSSTT) used for an electrical flashover test of suspension insulators. Rated voltage and frequency of the developed DRSSTT are 120 kV and 200 kHz, respectively. The developed DRSSTT was designed and constructed by applying solid-state electronics devices and knowledge of power electronics together. The developed DRSSTT has over advantages over the conventional Tesla transformer (CTT). The CTT has high power loss from the ignition caused by sparks of electrode of quenching gap, a cooling system requirement, large structure, high weight and high cost. In addition, it is not convenience to be used for the flashover test in a small testing room in the actual factory and on-site test. Therefore, the DRSSTT is necessary to develop. The aims of developing the DRSSTT are to be used to perform the flashover test of insulators and to reduce the equipment cost. The developed DRSSTT uses H-bridge inverter to drive a conventional Tesla coil. Four IGBTs in H-bridge configuration are employed to generate a square wave voltage with a resonant frequency which is close to the resonance frequencies of the primary and secondary circuit of Tesla transformer. Therefore, the voltage regulator, the high-voltage transformer, and the quenching gap are not required in the developed equipment. So, the developed DRSSTT are small size and low cost. However, there are weak points of the DRSSTT such as requirement of high rate current and voltage of electronics switching devices. The experiments have been carried out to confirm the performance of the developed DRSSTT. In the experiments, the developed DRSSTT with the height of 0.6 m was employed in the flashover test of insulators. The damped high-voltage with high-frequency of about 200 kHz is generated to make continually flashover on an insulator for 3 second to 5 second. The insulators under test are suspension type ANSI 52-1, ANSI 52-4 and post type ANSI 57-2. It is found that the DRSSTT can generate high voltage with frequency about 200 kHz (180 to 201 kHz) and make flashovers on the insulators according to the ANSI C29.1 standard. From the reasons above, the developed DRSSTT is very attractive to use for the flash test of insulators in the real practice.
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    Rogowski coil with an active integrator for measurement of switching impulse current
    (2013-09-02)
    Limcharoen, Worrakan
    ;
    Yutthagowith, Peerawut
    This paper presents design and construction of an impulse current measuring system based on a Rogowski coil with various types of integrators, a conventional RC integrator, a compensated RC integrator, and an active integrator. The developed measuring systems were designed for measurement of switching impulse current waveform used in a residual voltage test of arresters. The comparative measurement of the Rogowski coil with those integrators and non-inductive shunt resistor were carried out in an HV Laboratory. From the experiment results measured by the same Rogowski coil with various integrators show that all current measuring systems provide accurate front time. The Rogowski coil with the conventional RC and compensated integrators provide inaccurate measurement of inverse current peak and tail time. The Rogowski coil with the active integrator provides all fairly accurate waveform parameters when it was compared to the measured results by the non-inductive shunt resistor. © 2013 IEEE.
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    PSO based decentralized robust power system stabilizer for a multi-machine power system
    (2012-06-12)
    Kaitwanidvilai, Somyot
    ;
    Ussawapusitgul, Chanchai
    ;
    Limcharoen, Worrakan
    This paper presents a new technique to design a robust Power System Stabilizer (PSS) in multi-machine power system. The Particle Swarm Optimization (PSO) is adopted to find the optimal parameters of the predefined structure decentralized controller. The main objectives of this research are to reduce the oscillation and to increase the overall robust performance of the system. The proposed technique adopts the stability margin (ε) as the index of robustness and performance of the controlled system. In addition, the optimal weight selection, which is a difficult process of the robust loop shaping design, can be achieved by the proposed technique. In this paper, the performance of the proposed controller is investigated in the standard IEEE four generators system in comparison with the classical robust loop shaping control. The results of rotor speed deviation of generators by the proposed PSS and the conventional PSS verify the effectiveness of the proposed algorithm.