• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.199-206
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• 2010

Matrix converter is an energy conversion device of controlled power semiconductor switches that directly connects the three-phase source to the three-phase load. With no dc-link components for energy storage in the matrix converter the input current depends directly upon the load currents and the switch state of the converter. Therefore the unbalanced and distorted input voltages can result in unwanted output harmonic currents. This paper presents a current compensator based on neural network to improving output current quality for matrix converter under abnormal input voltage conditions. The effectiveness and feasibility of the proposed technique has been proven through numerical simulations and experimental tests.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.153-160
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• 2006

This paper presents a new compensating system, which consists of a shunt active filter and passive components for mitigating voltage and current disturbances arising from an Electric Arc Furnace (EAF). A novel control strategy is presented for the shunt active filter. An extended method based on instantaneous power theory in a rotating reference frame is developed for extraction of compensating signals. Since voltages at the point of common coupling contain low frequency interharmonics, conventional methods cannot be used for dc voltage regulation. Therefore, a new method is introduced for this purpose. The passive components limit the fast variations of load currents and mitigate voltage notching at the Point of Common Coupling (PCC). A three-phase electric arc furnace model is used to show power quality improvement through reactive power and harmonic compensation by a shunt active filter using the proposed control method. The system performance is investigated by simulation, which shows improvement in power quality indices such as flicker severity index.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.11
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• pp.563-571
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• 2003

In this paper, the control algorithm and control method for a combined system of shunt passive filter and series active filter in 3-phase 4-wire system are discussed. Moreover, the three-phase four-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and its 3th harmonics are termed as triple and zero sequence components that do not cancel each other in the system neutral. Consequently, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control algorithm for a series hybrid active system, whereas the control approach it adopts may directly influence its compensation characteristics. Hence, the advantage of this control algorithm is direct extraction of compensation voltage reference and the required rating of the series active filter is much smaller than that of a conventional shunt active filter. Some experiments were executed and experimental results from a prototype active power filter confirm the suitability of the proposed approach.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.761-765
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• 2006

At present, harmonic currents cause serious problems in power conversion system using the semiconductor switching device. Also some of the conversion system provokes harmonic currents against to the main power supply system and causes hindrances for the system. Main power impedance of the traditional LC passive filter method, influences on the filter characteristics and amplifies the harmonics when resonance phenomenon is occurred. And the traditional existing 2 level inverter systems show the limit in capacity of voltage and current in case of occurring sudden load change. So, to solve this problem active filter which uses cascaded H-bridge multi level inverter has been designed and ex-filter system circuits were totally investigated. With multi level active filtering system not only the size of filter but also the size of filter for transformer can be reduced by half and so as to the weight, while the capacity of inverter can be double sized and wave forms can be compensated exactly and precisely. Also by the benefit of the increase in rating capacity, the various currents owing to the load fluctuation can be dealt more steadily. In order to simulate the wave form of harmonics based on the measured data on the AC 25kV high speed Domestic Commercial railway, it was simulated with PSCAD/EMTDC and PSIM. Based on the results of this demonstration, the power supply system and inverter system would be more stable and also promoting its efficiency.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1046-1048
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• 2002

The increase of triplen harmonics in three-phase four-wire systems leads to overloaded neutral conductor, common-mode noise problems, derating of transformers, and so on. Various compensator has been designed to prevent the problems associated with the triplen harmonics. But these can not protect distribution system effectively because the triplen harmonic source is distributed extensively and distribution system type is diverse. This paper explain the operation and installation of single phase active power filter to eliminate triplen harmonics and then it is verified by simulation.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.149-150
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• 2016

STATCOM은 전력 계통에 병렬로 연결되어 역률 보상, 전압 보상 그리고 비선형 부하에 의해 야기되는 불필요한 고조파 전류를 보상하는 기능을 한다. 고조파 전류의 경우 대개 전원 주파수의 배수 형태로 발생하며, 이를 보상하기 위해 활용될 수 있는 다양한 제어기 중 하나로써 반복 제어기를 적용하였다. 공진 제어기의 무한한 합과 등가인 반복제어기의 경우, 모든 배수 고조파에 대한 제어가 가능하기 때문에 다양한 부하에 의한 예측 불가능한 고조파 전류를 보상해야 하는 STATCOM 제어에 적합하다. 본 논문에서는 반복제어기를 적용한 고조파 전류 제어기를 소개하고, 그 성능을 15kVA 축소 모델 실험으로 검증한다.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.287-289
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• 1988

A reactive power compensator whiych employs a 3-phase voltage source PWM converter is presented and ana lysed in this study. In this study, instantaneous reactive power compensator by the theort of instantaneous real and imaginary power are theoretically studied how to compensate reactive power occured by fundamental and harmonic reactive current. And we showed the compensation characteristic as well as the capacity of condenser.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.87-91
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• 2003

Most of the loads in industrial power distribution systems are balanced and connected to three wires power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating a large amount of non-characteristic harmonics. With the advent of power electronics and proliferation of non-linear loads in industrial power applications, power harmonics and their effects on power quality are a topic of concern. Harmonics by the unbalance voltage and non-linear loads, cause the increase of machine loss and heating. In order to allow current harmonic compensation, a filter must be installed. This paper describes the performance of passive filter under the voltage unbalance and non-linear load.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.374-381
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• 2005

The ability to provide quality power has become a significant issue in power systems. The main causes of poor power quality are harmonic currents, poor power factor, supply-voltage variations, etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply-voltage variation (sag or swell) at the load side is presented in this paper. The operation and rating issues of the proposed Single-phase Unified Power Quality Conditioner are also highlighted. To reduce the total cost while simultaneously increasing the performance, the system is fully digitally controlled using the fixed-point TMS320F240 digital signal processor. The performances of the UPQC, which is composed by shunt and series PWM controlled-converters, have been verified on a laboratory prototype.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.137-139
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• 1988

A reactive power compensator whitch employs a three phase voltage source PWM converter is presented and analysed in this study. In this study, instantaneous reactive power compensator by the theory of instantaneous real and imaginary power are theoretically studied how to compensate reactive power occured by fundamental and harmonic reactive current. And we showed the compensation characteristics by comparing the experimental results with those of computer simulation.