• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.258-264
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• 2006

This paper presents an integrative control scheme for series-type active power filters combined with shunt passive filters not only to compensate for the source voltage unbalance and current harmonics but also to correct the power factor. To reduce the power capacity of the active filters, passive filters are connected in parallel. Diode rectifiers are replaced by the PWM converters in order to feed the real power back to the source. Power factor control is performed by changing the phase of the load voltage so that the phase of the source current coincides with that of the source voltage. The resultant voltage reference is the addition of the voltage component compensating for the source voltage unbalance and harmonic currents and the voltage component correcting the power factor. The validity of the proposed algorithm has been verified by experimental results.

• Journal of Power Electronics
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• 제7권3호
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• pp.257-264
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• 2007

Active power filters can be cost-effective for use in practical systems with the insertion of a few passive elements in shunt or series configuration. The resulting hybrid filters can be designed to provide dominant lower order harmonic elimination and reactive power support by the passive elements so that the burden on the active filter counterpart is reduced. In this paper, the rate reduction in the shunt active filter is estimated when it is connected in parallel with suitable passive tuned harmonic filters. The active filtering system is based on an appropriate control scheme. The simulation and the experimental results of the shunt active filter, along with the estimated value of reduction in rating, show that the hybrid shunt filtering system is quite effective in compensating for the harmonics and reactive power, in addition to being cost-effective.

• Journal of Power Electronics
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• 제11권3호
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• pp.311-318
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• 2011

LCL filters installed at converter outputs offer a higher harmonic attenuation than L filters. However, as a three order resonant circuit, it is difficult to stabilize and has a risk of oscillating with the power grid. Therefore, careful design is required to damp LCL resonance. Compared to a passive damping method, an active damping method is a more attractive solution for this problem, since it avoids extra power losses. In this paper, the damping capabilities of capacitor current, capacitor voltage, and grid-side current feedback methods, are analyzed under the discrete-time state-space model. Theoretical analysis shows that the grid-side current feedback method is more suitable for use in active power filters, because it can damp LCL resonance more effectively than the other two methods when the ratio of the resonance and the control frequency is between 0.225 and 0.325. Furthermore, since there is no need for extra sensors for additional states measurements, this method provides a cost-efficient solution. To support the theoretical analysis, the proposed method is tested on a 7-kVA single-phase shunt active power filter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.752-755
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• 2000

This paper describes a new algorithm for active power filters which can be control source current symmetrically under unbalanced condition in power system. Positive sequency voltage is detected by symmetrical coordinate method and compensating reference current of active power filters is calculated using by accurate phase angle information of positive sequency voltage. The basic principle of the proposed method is described in detail and the conventional and proposed phase detecting methods are compared and discussed through the simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.292-295
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• 2003

Conventional methods in time / frequency domain for evaluating the compensation performance of active power filters are not provided easy solutions. So, the authors have previously proposed 3-D current coordinates which is composed into active component, fundamental reactive component and distorted component of nonlinear loads current. This method has excellent performance, but can not evaluate the characteristics of nonlinear load current whether it is inductive or capacitive. Therefore, To overcome problems mentioned previously, this paper deals with the simple Average power theory and the expanded 3-D current coordinates for evaluating the compensation performance of active power filters. To confirm the validity, active power filters simulator is developed using C-language. From the simulation, results are discuss their utility.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2549-2552
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• 1999

The fictitious power theory in time domain is very easy to understand, but power analyzing time of active power is increased, because power is analyzed using signal techniques based on the correlation between voltage and current waveforms. Also, conventional methods in time/frequency domain to evaluate the compensation performance of active power filters are not provided easy solutions. So, the authors have previously proposed 3-D current coordinates which is composed into active component, fundamental reactive component and distorted component of nonlinear loads current. This method has excellent performance, but can not evaluate the characteristics of nonlinear load current whether inductive or capacitive. Therefore, To overcome problems mentioned previously, this paper deals with the simple instantaneous power theory and the modified 3-D current coordinates for evaluating the compensation performance of active power filters. To confirm the validity, active power filters simulator is developed using C-language. From the simulation, results are discussed their utility.

• 전력전자학회논문지
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• 제6권6호
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• pp.514-524
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• 2001

종전의 평균전력이론은 3상 불평형과 같은 전원전압 조건에 따라 능동전력필터의 보상기준전류가 결정적으로 영향을 받는 문제점이 있다. 이와 같은 불평형된 능동전력 필터의 보상전류는 결과적으로 불평형이 되는 원인이 된다. 본 연구에서는 불평형 전원 하에서도 유효전력과 기본파 무효전력의 동기 검출법에 입각하여 비선형 부하전류의 유효성분과 기본파 무효성분 그리고 왜형 성분을 각각 독립적으로 분해가 가능한 평균전력 이론을 제시하였다. 제안된 이론은 간단한 평균전력 이론을 기반으로 하고 잇기 때문에 우선 이해사기 쉽고 구현이 간단하다는 장점이 있다. 본 연구 에서는 고속의 DSP(digital signal processor)에 의하여 이와 같은 문제을 어느정 도 해결할 수있었다. 제안된 방법의 타당성을 입증하기 위해서 TMS320C31-DSP기반의 전력분석 시스템을 제작하였다. b상 전압이 15% 불평형된 3상 3전 전원하에서 시뮬레이션 및 실험을 수행한 결과 종전의 방법에 비하여 제안된 알고리즘의 유용성을 입증할수 있었다.

• Journal of Power Electronics
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• 제13권6호
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• pp.1058-1069
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• 2013

This paper proposes and designs a new output filter called an LCFL filter for application to three phase three wire shunt active power filters (SAPF). This LCFL filter is derived from a traditional LCL filter by replacing its capacitor with a C-type filter, and then constructing an L-C-type Filter-L (LCFL) topology. The LCFL filter can provide better switching ripple attenuation capability than traditional passive damped LCL filters. The LC branch series resonant frequency of the LCFL filter is set at the switching frequency, which can bypass most of the switching harmonic current generated by a SAPF converter. As a result, the power losses in the damping resistor of the LCFL filter can be reduced when compared to traditional passive damped LCL filters. The principle and parameter design of the LCFL filter are presented in this paper, as well as a comparison to traditional passive damped LCL filters. Simulation and experimental results are presented to validate the theoretical analyses and effectiveness of the LCFL filter.

• Journal of Power Electronics
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• 제11권6호
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• pp.914-921
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• 2011

Commencing with incandescent light bulbs, every load today creates harmonics. Unfortunately, these loads vary with respect to their amount of harmonic content and their response to problems caused by harmonics. The prevalent difficulties with harmonics are voltage and current waveform distortions. In addition, Electronic equipment like computers, battery chargers, electronic ballasts, variable frequency drives, and switching mode power supplies generate perilous amounts of harmonics. Issues related to harmonics are of a greater concern to engineers and building designers because they do more than just distort voltage waveforms, they can overheat the building wiring, cause nuisance tripping, overheat transformer units, and cause random end-user equipment failures. Thus power quality is becoming more and more serious with each passing day. As a result, active power filters (APFs) have gained a lot of attention due to their excellent harmonic compensation. However, the performance of the active filters seems to have contradictions with different control techniques. The main objective of this paper is to analyze shunt active filters with fuzzy and pi controllers. To carry out this analysis, active and reactive current methods ($i_d-i_q$) are considered. Extensive simulations were carried out. The simulations were performed under balance, unbalanced and non sinusoidal conditions. The results validate the dynamic behavior of fuzzy logic controllers over PI controllers.

• Journal of Power Electronics
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• 제18권3호
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• pp.871-878
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• 2018

In this paper, the conducted EMI reduction performances of active feed-forward current-sensing current-actuation (CSCA) and voltage-sensing current-actuation (VSCA) filters for a three-phase induction motor drive system are evaluated by experiments. For comparison purposes, the conducted EMI (CM emission, DM emission and total emission) of a three-phase induction motor drive with a conventional CM choke, a conventional CM choke in series with an active VSCA filter, and an active CSCA filter (where the CM choke was modified and used as a sensing current transformer) were compared to the case of a system without any filter inserted. Experimental results show that the active CSCA and VSCA filters can improve the CM reduction performance of the conventional CM choke by about 5 dB especially at low-frequencies. However, for DM comparisons, it shows that there is no different between cases with and without filters inserted.