• Journal of Power Electronics
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• v.18 no.3
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• pp.863-870
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• 2018

The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

• Journal of Power Electronics
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• v.10 no.1
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• pp.91-96
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• 2010

In this paper, a simplified control algorithm for a three-phase, four-wire unified power quality conditioner (UPQC) is presented to compensate for supply voltage distortions/unbalance, supply current harmonics, the supply neutral current, the reactive power and the load unbalance as well as to maintain zero voltage regulation (ZVR) at the point of common coupling (PCC). The UPQC is realized by the integration of series and shunt active filters (AFs) sharing a common dc bus capacitor. The shunt AF is realized using a three-phase, four leg voltage source inverter (VSI) and the series AF is realized using a three-phase, three leg VSI. A dynamic model of the UPQC is developed in the MATLAB/SIMULINK environment and the simulation results demonstrating the power quality improvement in the system are presented for different supply and load conditions.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.498-500
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• 2005

This paper presents a unified control scheme for series-type active power filters combined with shunt passive filters for the source voltage unbalance compensation and the power factor correction simultaneously. The power factor correction is achieved by controlling the amplitude of reactive power current in a series filter as zero in a synchronously rotating reference frame. The proposed algorithm successfully compensates the source voltage unbalance and the power factor. The validity of the proposed scheme has been verified by simulation for a 3-kVA hybrid active power filter system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1085-1086
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• 2008

Shunt active filter can compensate harmonic current of utility results from non-linear loads such as rectifiers, cycloconverters and arc furnaces. It has the same structure as photovoltaic(PV) generation system. So, It was proposed the system that generates PV power and also has active filter function. It is called PV-AF(Photovoltaic and Active Filter) power generation system. Islanding can be occurred in an inverter based dispersed generation system, when the system disconnected from utility and loads are entirely supplied by PV system only. Islanding may result in interference to grid protection devices, equipment damage, and even personnel safety hazards. Therefore, islanding has to be detected and protected. The conventional anti-islanding methods have NDZ(None-Detection Zone) or power quality degradation. But PV-AF power generation system has the function of not only shunt active filter but also anti-islanding method without NDZ. In this paper, a novel anti-islanding method for PV-AF system is proposed and analysed in detail.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.802-807
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• 1998

The main drawback of parallel type active power filters (APF) is the large capacity required for harmonic compensation. This paper evaluates the APF capacity requirement of harmonic/reactive power compensation for thyristor converter load. Theoretically achievable maximum power factor under partial load is evaluated. And it is shown that the APF capacity can be considerably reduced while slightly sacrificing the filtering performance by deliberately limiting the peak current of the APF.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1714-1728
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• 2016

This paper presents improved harmonics extraction based on Adaptive Linear Neuron (ADALINE) algorithm for single phase photovoltaic (PV) shunt active power filter (SAPF). The proposed algorithm, named later as Improved ADALINE, contributes to better performance by removing cosine factor and sum of element that are considered as unnecessary features inside the existing algorithm, known as Modified Widrow-Hoff (W-H) ADALINE. A new updating technique, named as Fundamental Active Current, is introduced to replace the role of the weight factor inside the previous updating technique. For evaluation and comparison purposes, both proposed and existing algorithms have been developed. The PV SAPF with both algorithms was simulated in MATLAB-Simulink respectively, with and without operation or connection of PV. For hardware implementation, laboratory prototype has been developed and the proposed algorithm was programmed in TMS320F28335 DSP board. Steady state operation and three critical dynamic operations, which involve change of nonlinear loads, off-on operation between PV and SAPF, and change of irradiances, were carried out for performance evaluation. From the results and analysis, the Improved ADALINE algorithm shows the best performances with low total harmonic distortion, fast response time and high source power reduction. It performs well in both steady state and dynamic operations as compared to the Modified W-H ADALINE algorithm.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.225-227
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• 2002

In this paper, novel concept of a photovoltaic(PV) power generation system adding the function of active filter(AF) is proposed. Even PV power generation system can be treated to a harmonics source for the power distribution system, it is necessary that the function of AF system in grid connected PV power generation system. Active Filters intended for harmonic solutions are expending their functions from harmonic compensation of nonlinear loads into harmonic isolation between utilities and consumer, and harmonic damping throughout power distribution system. So, the PV system combined the function of AF system can be usefully applied in power distribution system. Here, the control strategy of PV-AF system is introduced.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.462-465
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• 2008

본 연구에서는 장거리 배전선로의 전압 고조파 확산을 억제하기 위한 HBML 능동전력필터(HBML-AFU : H-Bridge Multi-Level Active Power Filter Unit)를 제시하였다. 버스(Bus)의 전압 고조파는 60Hz 버터워쓰 대역통과필터(BPF : Band Pass Filter)에 의하여 검출하였다. 제안된 시스템의 보상전원으로는 배터리($24v{\times}2=48v$)를 사용하였다. 제안된 시스템의 타당성은 PSIM시뮬레이션에 의하여 과도상태 및 정상상태에서 확인하였다.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.201-203
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• 2005

A new 3-phase line-interactive UPS(Uninterruptible Power Supply) system with parallel-series active power-line conditioning capability using AC line reactor and two four-leg PWM VSCs(Voltage Source Converters) was introduced recently, In this paper, the strategy of voltage control in suggested UPS system is explained. The objective of proposed voltage controllers in parallel(shunt) and series PWM VSC is to guarantee satisfactory characteristics in steady state and transient state.

• Journal of Power Electronics
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• v.15 no.3
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• pp.819-829
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• 2015

This paper presents a shunt active power filter (SAPF) for compensating inter-harmonics and harmonics when inter-harmonics content is evident in the grid. The principle of inter-harmonics generation in the grid was analyzed, and the inter-harmonics effect on repetitive controllers was discussed in terms of control performance. Traditional repetitive controllers are not applicable in inter-harmonic compensation. Moreover, the effect of an ideal controller on harmonics signals was analyzed on the basis of the internal model principle. The repetitive controller was improved in the form of a basis function according to theoretical analysis. The finite-dimensional repetitive controller, which is also called the multiple-period repetitive controller, was designed for the control of multiple periodic signals. A selective harmonic compensation system was developed with SAPF. This system can be used to compensate harmonics and inter-harmonics in the grid. Finally, system control performance was verified by simulation and experimental results.