• Journal of Power Electronics
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• 제17권1호
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• pp.172-180
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• 2017

The repetitive control (RC) strategy is widely used in AC power systems because of its high performance in tracking period signal and suppressing steady-state error. However, the dynamic response of RC is determined by the fundamental period delay $T_0$ existing in the internal model. In the current study, a ($nk{\pm}i$)-order harmonic RC structure is proposed to improve dynamic performance. The proposed structure has less data memory and can improve the tracking speed by n/2 times. $T_0$ proves the effectiveness of the ($nk{\pm}i$)-order RC strategy. The simulation and experiments of ($6k{\pm}1$)-order and ($4k{\pm}1$)-order RC strategy used in the voltage source inverter is conducted in this study to control the harmonic current source, which shows the validity and advantages of the proposed structure.

• Journal of Power Electronics
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• 제18권6호
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• pp.1889-1900
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• 2018

Harmonic current mitigation is vital in power distribution networks owing to the inflow of nonlinear loads, distributed generation, and renewable energy sources. The active power filter (APF) is the current electrical equipment that can dynamically compensate for harmonic distortion and eliminate asymmetrical loads. The compensation performance of an APF largely depends on the control strategy applied to the voltage source inverter (VSI). Model predictive control (MPC) has been demonstrated to be one of the effective control approaches to providing fast dynamic responses. This approach covers different types of power converters due to its several advantages, such as flexible control scheme and simple inclusion of nonlinearities and constraints within the controller design. In this study, a finite control set-MPC technique is proposed for the control of VSIs. Unlike conventional control methods, the proposed technique uses a discrete time model of the shunt APF to predict the future behavior of harmonic currents and determine the cost function so as to optimize current errors through the selection of appropriate switching states. The viability of this strategy in terms of harmonic mitigation is verified in MATLAB/Simulink. Experimental results show that MPC performs well in terms of reduced total harmonic distortion and is effective in APFs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.205-207
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• 2005

In this paper, the Point of Common Coupling (PCC) is selected to analyze harmonic characteristic of distribution system by IEC 61000 - 3 - 6 in Electromagnetic Compatibility(EMC). Harmonic voltage and current were measured at the PCC of real distribution system. Harmonic distribution, nonlinear load component and Total Harmonic Distortion(THD) were verified by measurement. The effective and accurate modelling of real distribution system were proved through a analysis of harmonic impedance, voltage and current in steady-state. Harmonic transfer characteristic in distribution system were summarized and investigated through a analysis of harmonic voltage and harmonic current in harmonic current source.

• Journal of Power Electronics
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• 제9권3호
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• pp.403-409
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• 2009

Automatically tuned passive filters can improve power quality to a great extent in power systems. A novel three-phase shunt auto-tuned filter is designed to effectively compensate source current harmonics and to provide reactive power required by the non-linear load, which draws a highly reactive, harmonic-rich current from the supply. An artificial neural network (ANN) based controller selects filter component values in accordance with reactive power requirement and harmonic compensation. Traditional passive filters are permanently connected to the system and draw large amounts of source current even under light load conditions. By using auto-tuned filters, the passive filter components can be controlled according to load variations and, hence, draw only required source currents. The selection is done by the ANN with the help of a properly tuned knowledge base to provide instantaneous compensation using a digital controller.

• 대한전자공학회논문지
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• 제27권9호
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• pp.1427-1435
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• 1990

This paper proposes the Selected Harmonic Elimination Pluse Width Modulation (SHE PW) scheme toreduce the ahrmonic components of source line current. To eliminate the low order harmonics which affects the source dominatly, we apply the Fourier series analysis to line current waveforms and then find out the switching patterns using the SHE PWM scheme. In addition to the analysis of harmonic effects, the three phase filter circuit is used to reduce high order harmonics. For the experimental realization, the converter circuit with power Transistor(PTR) is designed and the Pulse Time Control(PTC) is applied. The line current and the load voltage are measured under the condition of three phase application, highly inductive load.

• Journal of Power Electronics
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• 제15권2호
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• pp.497-503
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• 2015

This paper analyses the harmonic pollution to power grids caused by several high-power rectifiers, summarizes the requirements for rectifiers in suppressing grid-side current harmonics and optimizes a new-type of current source PWM rectifier with a hybrid switch. The rectifier with a hybrid switch boasts significant current characteristics and cost advantages in the high-power area. To further enhance the working frequency of the current source rectifier with a hybrid switch for suppressing grid-side harmonics and reducing the inductance size, this paper proposes an optimal control strategy based on space vector. It also verifies that the optimal control strategy based on space vector can reduce the total harmonic distortion of the grid-side current of the rectifier with a hybrid switch via circuit simulation and experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.382-391
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• 2005

Increasing of the nonlinear type power electronics equipment, power conditioning systems (PCS) have been researched and developed for many years in order to compensate for harmonic disturbances and reactive power. PCS's not only improve harmonic current and power factor in the ac grid line but also achieves energy saving used by the renewable energy source (RES). In this paper, the implementation of a current controlled voltage source inverter (CCVSI) using RES for PCS is presented. The basic principle and control algorithm is theoretically analyzed and the design methodology of the system is discussed. The proposed system could achieve power quality control (PQC) to reduce harmonic current and improve power factor, and demand side management (DSM) to supply active power simultaneously, which are both operated by the polarized ramp time (PRT) current control algorithm and the grid-interactive current control algorithm. A 1KVA test model of the CCVSI has been built using IGBT controlled by a digital signal processor (DSP). To verify the proposed system, a comprehensive evaluation with theoretical analysis, simulation and experimental results is presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.234-236
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• 2006

In this paper, APF(Active Power Filter) will be treated in order to improve the output current distortion of the AC source. APF generates the harmonic current which contributes to a source side harmonic reduction. We can extract the compensating current of the parallel APF with phase transformations and the proposed current control method. Therefore, the calculation times is short and the control method is simple compared with conventional hysteresis methods. Experimental results verify that the system using the proposed method appers a good performance.

• 전력전자학회논문지
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• 제12권1호
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• pp.27-36
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• 2007

본 논문은 전원전압이 불평형이고 왜곡될 경우의 3상 PWM 컨버터의 전류제어기법을 제안한다. 전원전압의 왜곡에 대한 대책은 종래의 일반적인 전류 제어기에 5차, 7차 고조파 전류제어기를 추가하여 전원전류에 저차고조파가 나타나는 것을 제거한다. 그리고 전원전압 불평형의 경우, 역상분 전류제어기를 추가함으로써 전원전류를 평형으로 제어하거나 직류출력 전압의 리플을 감소시킬 수 있다. 제안된 제어 알고리즘의 타당성을 실험을 통하여 검증하였다.

• 조명전기설비학회논문지
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• 제25권4호
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• pp.57-64
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• 2011

Most of the user has been used linear load and non-linear load. The former is usually inductive load which is needed power factor compensation, the latter is power conversion system device. Actually two kinds of load is used together in the customer application. Generally capacitor is used for power-factor compensation of inductive load and reduction harmonics of non linear load with reactor. Non-linear load generates harmonic current for its energy conversion process. If harmonic current pass along the low impedance side of distribution system, the magnification of voltage and current is appeared by the series and parallel resonance. As a result, condenser has received a bitter electrical stress by the harmonic component. In this paper, we analyzed that how resonance is changed by the 5-th harmonic current pattern and proposed an alternative plan for non-magnification.