• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.222-227
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• 1997

Unbalanced source voltages due to unbalanced loads in the 3-phase power system is decomposed into positive, negative and zero sequence components. Also, assuming there is no neutural path in the system, the zero sequence component is not shown. Therefore, it is possible to compensate unbalanced source voltage by canceling the negative sequency component of the voltages of the source. In this paper, an algorithm compensating unbalanced source voltages by canceling the negative sequence component is presented and analysis of instantaneous voltage compensator using 3-phase PWM inverter is carried out through computer simulation.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권12호
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• pp.615-623
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• 2001

In this paper, we study a series active power filter to compensate current harmonics and unbalanced source voltages. Conventional control methods for compensating unbalanced source voltages use source voltages to calculate compensation voltages, and in addition use load voltages to regulate load voltages. But the proposed control method uses load voltage to compensate unbalanced source voltages and regulate load voltages. And we propose a control method to reduce current harmonics which can calculate compensation voltages directly from source currents and load voltages. By well-matched operation of two control methods, the series active power filter can compensate current harmonics, unbalanced source voltages, and regulate load voltages. We compose a combined system of the series active power filter and parallel passive filters to confirm a validity of proposed control methods. The results from experiments are presented to demonstrate effectiveness of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.191-194
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• 2001

In this paper, we propose a series active power filter control method to compensate current harmonics and unbalanced source voltage. The system is composed of series active power filter and shunt passive filer that are tuned 5th and 7th harmonics. In this conventional system, series active power filter complements drawbacks of the shunt passive filter, namely improves harmonic compensation characteristics, and compensates unbalanced source voltage. In the proposed algorithm, compensation voltage for harmonic reduction is calculated by performance function, and compensation voltage for unbalanced source voltage is calculated in based on a synchronous reference frame. So, ultimate compensation voltage is sum of those two compensation voltages. By computer simulation, we verify the excellency of proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.319-322
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• 2001

In this paper, a 3phase-3wire series active power filter compensating current harmonics and unbalanced source voltages is presented. The system is composed of series active power filter and shunt passive filters that are tuned 5th and 7th harmonics. In this system, series active power filter improves harmonic compensation characteristics of the shunt passive filters and compensates the unbalanced source voltages. In the proposed algorithm, compensation voltage for harmonic reduction is calculated by a performance function, and compensation voltage for the unbalanced source voltage is calculated in based on the synchronous reference frame. Some results obtained from the experimental model using the proposed method are presented to demonstrate and confirm its validity.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권5호
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• pp.249-257
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• 2002

In this paper, a novel control scheme compensating source voltage unbalance and harmonic currents for the combined system of series active and shunt passive power filter is proposed, where no low/high-pass filters are used in deriving the reference voltage for compensation. The phase angle and the reference voltages compensating for harmonic current and unbalanced voltage are derived from the positive sequence component of the unbalanced voltage set, which is simply obtained by using digital all-pass filters. In order to remove the phase delay in generating the reference voltage for compensation, the reference of 5th and 7th harmonic components is predicted one-sampling ahead. The validity of the proposed scheme has been verified for 3[kVA] proto-type active power filter system.

• 전력전자학회논문지
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• 제4권3호
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• pp.275-284
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• 1999

3산 전력 시스템에서 불평형 전원의 전압은 대칭좌표법에 의하여 정상, 역상, 영상성분으로 각각 분해 될 수 있고 또한 전력 시스템에 중성선이 없는 경우 영상성분은 부하측에 나타나지 않게 된다. 따라서 중성선이 없는 불평형 시스템에서는 전원측의 역상성분만을 검출하여 보상함으로써 부하측에 평형된 전압을 공급할 수 있을 뿐만 아니라 정상성분의 크기를 제어함으로써 부하에 인가되는 전압의 크기를 조정하는 것이 가능하다. 아울러 이러한 불평형 전압에 의한 각 대칭분은 3상 2상 변환을 통한 동기좌표축상에서의 효율적인 검출이 가능한데, 본 논문에서는 전원의 불평형 성분을 동기좌표축 상에서 순시적으로 검출하여 이를 보상하고 부하의 전압조정 기능 역시 수행하는 순간전압보상기의 보상 알고리즘 및 이때 좌표변환시 필요한 전원의 위상각 정보를 전원의 정상성분에 일치시키는 새로운 위상각 검출 알고리즘을 제안한다. 제안된 보상 시스템의 성능 및 특성을 시뮬레이션을 통하여 해석하고 실험으로써 검증하였다.

• Journal of Power Electronics
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• 제8권2호
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• pp.131-140
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• 2008

This paper presents a new control approach of DSTATCOM (distribution static compensator) for compensation of reactive power, unbalanced loading and harmonic currents under unbalanced non-sinusoidal ac mains. The control of DSTATCOM is achieved using Adaline based current estimator based on LMS algorithm to maintain source currents real and undistorted. The dc bus voltage of voltage source converter (VSC) working as DSTATCOM is maintained at constant voltage using a proportional-integral (PI) controller. The DSTATCOM system alongwith proposed control scheme is modeled in MATLAB to simulate the behavior of the system. The practical implementation of the DSTATCOM is carried out using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. Simulated and implementation results are presented to demonstrate the effectiveness of the DSTATCOM with Adaline based control to meet the severe load perturbations with different types of loads (linear and non-linear) under distorted and unbalanced AC mains.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.196-199
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• 2001

This paper deals with current harmonics and unbalanced source voltages compensation using combined filter system. Filter system consists of a series active filter and parallel passive filters. Passive filters were a traditional method to compensate current harmonics, so those were installed in power system widely. The active filter can be a substitution to improve filtering characteristics and complement drawbacks of the passive filter. The combined system of the active power filter and passive filter can has a better compensation performances and economical goods. The series type active power filter injects compensation voltage into power system by transformers. It's compensation principle is able to applicate for voltage compensation. A new control algorithm for series active filter to compensate current harmonics and unbalanced source voltages is proposed. In the proposed algorithm, a compensation voltage for harmonic reduction is calculated directly by instantaneous reactive power theory, and a compensation voltage for unbalanced source voltage is calculated in based on a synchronous reference frame. By experiments, we show validity of proposed compensation method.

• Journal of Power Electronics
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• 제16권6호
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• pp.2192-2201
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• 2016

Wind energy is currently the fastest-growing electricity source worldwide. The cost efficiency of wind generators must be high because these generators have to compete with other energy sources. In this paper, a system that utilizes an open-winding permanent-magnet synchronous generator is studied for wind-energy generation. The proposed system controls generated power through an auxiliary voltage source inverter. The VA rating of the auxiliary inverter is only a fraction of the system-rated power. An adjusted control system, which consists of two main parts, is implemented to control the generator power and the grid-side converter. This paper introduces a study on the effect of unbalanced voltages for the wind-generation system. The proposed system is designed and simulated using MATLAB/Simulink software. Theoretical and experimental results verify the validity of the proposed system to achieve the power management requirements for balanced and unbalanced voltage conditions of the grid.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.359-360
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• 2016

This paper presents a new predictive current control (PCC) method to achieve the coordinate control of power and current of the matrix converter under unbalanced input voltages. In order to control the power fluctuation in the input side, the flexible source current reference is generated based on the positive-negative sequence components of the input voltage. The optimal switching state to adjust source and load currents is selected by minimization the cost function which is obtained from the sum of the absolute errors between the current references and their predictive values. Simulation results are given to validate the effectiveness of the proposed PCC method.