• 전자공학회논문지
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• 제54권8호
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• pp.115-122
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• 2017

본 논문에서는 슬라이닥을 이용하는 새로운 역률보상시스템을 제안한다. 제안하는 역률보상시스템은 슬라이닥의 출력전압을 커패시터에 인가하여 역률을 보상하는 구조이다. 기존의 커패시터 뱅크 방법을 이용하는 역률보상시스템은 선택 가능한 커패시터 용량이 한정되어 있어 부하 상황에 따라 역률 보상 오차가 발생하지만, 제안 시스템은 커패시터 인가 전압을 슬라이닥을 이용하여 세밀하게 변화시킬 수 있어 변화하는 부하를 추종하여 오차 없이 역률을 100%까지 보상할 수 있다. 기존 시스템과 제안 시스템을 비교하여 제시하고, 제안 시스템의 역률 보상 성능이 우수함을 모의실험과 실험을 통해 확인한다. 제안 시스템을 수용가에 설치할 경우 역률 개선을 통한 전기료 감소, 선로손실 감소, 부하 용량 증대 효과가 기대된다. 특히 발전 사업가측에서는 역률 보상 성능의 향상으로 송전 여유 용량 확보와 발전량 절감이 가능하다.

• 복식문화연구
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• 제23권1호
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• pp.117-125
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• 2015

The purpose of this study is to evaluate the differences of body compensation image on variations in the shoulder height and width of power shoulder raglan sleeve jacket. Nine samples were examined: 3 variations of the shoulder height and 3 variations of the shoulder width. The data was evaluated by 123 fashion design majors. The results were as follows; as a result of analyzing the body compensation image according to changes in the shoulder height and width of power shoulder raglan sleeve jacket, five factors were selected; the shoulder compensation factor, the bust compensation factor, the waist compensation factor, the arm compensation factor and the neck compensation factor. Among these factors, the shoulder compensation factor is the most important factor. Examining the major effect of the body compensation image based on changes in the shoulder height and width of power shoulder raglan sleeve jacket, it had an independent influence on factors about waist, neck, shoulder and arm compensation except a factor about bust compensation, had an influence on interacting effect of factors about shoulder, bust, waist, arm compensation, and it had no influence on interacting effect of a factor about neck compensation. This shows that the shoulder height has larger effect on neck compensation image than the shoulder width in power shoulder raglan sleeve jacket.

• 전기학회논문지P
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• 제67권3호
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• pp.155-159
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• 2018

Recently, the expansion or establishment of facilities for the logistics system is increasing. Conveyor facilities play a major role in sorting and transporting logistics. Induction motors are widely used for the operation of these conveyor systems. In the logistics system, a large number of induction motors are used. These motors have a considerable distance from the power source side and have a low power factor. The installation position for the power factor compensation of the induction motor is very important. Since the voltage drop depends on the length of the line, it is an important parameter in capacitor capacity determination for power factor compensation. The capacity of the capacitors installed to compensate the power factor of the inductive load should be designed to the extent that self-excitation does not occur. In this study, we analyze the method of compensating the proper power factor considering the voltage drop and the installation position of the induction motor in the logistics system.

• 전자공학회논문지
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• 제54권8호
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• pp.107-114
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• 2017

본 논문에서는 3상 4선식 전력계통에서 새로운 전압제어 방식의 역률보상시스템을 제안한다. 제안하는 전압제어 방식의 역률보상시스템은 슬라이닥을 이용하여 가변되는 출력전압을 커패시터에 인가하는 것으로 보상에 필요한 무효전력을 생성한다. 기존의 커패시터 뱅크 방법을 이용하는 역률보상시스템은 선택 가능한 커패시터 용량이 한정되어 있어 부하 상황에 따라 역률보상 오차가 발생하지만, 제안 시스템은 변화하는 부하를 추종하여 오차 없이 역률을 100%까지 보상할 수 있다. 본 논문에서는 3상 4선식 전력계통에서 전압제어 방식의 역률보상시스템과 제어 알고리즘을 개발하였고 모의실험과 실험을 통해 성능을 확인한다. 제안 시스템을 수용가에 설치할 경우 역률 개선을 통한 전기료 감소, 선로손실 감소, 부하 용량 증대 효과가 기대된다. 특히 발전 사업가 측에서는 역률 보상 성능의 향상으로 송전 여유 용량 확보와 발전량 절감이 가능하다.

• 전기학회논문지P
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• 제57권3호
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• pp.225-230
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• 2008

Reactor starting method has the advantage of simplicity and closed transition in spite of lower starting torque per kVA. This method allows a smooth start with almost no observable disturbance on transition and is suitable for applications such as centrifugal pumps or fans. Reactive power doesn't contribute to work but needs to sustain the electromagnetic field required for the induction motor to operate. Starting power factor of induction motor is specially lower than running power factor. Power factor application is needed to compensate for the lower power factor of induction motor. This power factor compensation systems is occasionally being hit by the effects of the starting reactor connection position at the starting, stopping of high-voltage induction motor. This paper describes voltage and current stress affected by the installation position of power factor compensation application at the reactor starting method.

• Journal of Power Electronics
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• 제19권6호
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• pp.1380-1392
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• 2019

Input filters are very important to matrix converters (MCs). They are used to improve grid side current waveform quality and to reduce the input voltage distortion supplied to the grid side. Due to the effects of the input filter and the output power, the grid side power factor (PF) is not at unity when the input power factor angle is zero. In this paper, the displacement angle between the grid side phase current and the phase voltage affected by the input filter parameters and output power is analyzed. Based on this, a new grid side PF unity compensation method implemented in the indirect space vector pulse width modulation (ISVPWM) method is presented, which has a larger compensation angle than the traditional compensation method, showing a higher grid side PF at unity in a wide output power range. Simulation and experimental results verify that the analysis of the displacement angle between the grid side phase current and the phase voltage affected by the input filter and output power is right and that the proposed compensation method has a better grid side PF at unity.

• 전력전자학회논문지
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• 제26권4호
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• pp.302-305
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• 2021

Selection of the optimal inductance for power factor improvement of a buck AC/DC light-emitting diode (LED) driver with wide input voltage range is described in this study. The power factor change based on the slope compensation is obtained for various normalized output current (NOC) values using discrete-time domain analysis. The possibility of implementing constant slope compensation is described using power factor curves for various NOC values. NOC = 0.5 is chosen for the value of inductance with consideration for the simple implementation and reduction of inductor size. Experimental results of the inductance corresponding to NOC = 0.5 are presented.

• Journal of Power Electronics
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• 제19권5호
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• pp.1315-1325
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• 2019

Aiming at the negative sequence and harmonic problems in the operation of railway static power conditioners, an optimization compensation strategy for negative sequence and harmonics is studied in this paper. First, the hybrid RPC topology and compensation principle are analyzed to obtain different compensation zone states and current capacities. Second, in order to optimize the RPC capacity configuration, the minimum RPC compensation capacity is calculated according to constraint conditions, and the optimal compensation coefficient and compensation angle are obtained. In addition, the voltage unbalance ${\varepsilon}_U$ and power factor requirements are satisfied. A PSO (Particle Swarm Optimization) algorithm is used to calculate the three indexes for minimum compensating energy. The proposed method can precisely calculate the optimal compensation capacity in real time. Finally, MATLAB simulations and an experimental platform verify the effectiveness and economics of the proposed algorithm.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권7호
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• pp.475-482
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• 2000

This paper presents a novel power-factor correction method using customer STATCOM which generally improves the power quality of electric customers. Customer STATCOM detects the reactive currents of a induction motor(IM) and so injects compensation currents which is in 180$^{\circ}$ phase with load currents that the reactive power of IM is compensated. In particular, the paper proposes the general compensation current references in the synchronous coordinate system and makes converter output voltages using space-vector PWM. The compensation effect of customer STATCOM is confirmed through the simulation according to the operation condition of an induction motor (at no load and full load).

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1380-1388
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• 2013

The conventional graphical representation of the instantaneous compensation power flow for single-phase active power filters(APFs) simply represents the active power flow and the reactive power flow which flowing between the power source and the active filter / the load. But, this method does not provide the information about the rectification mode and the compensation mode of APFs, especially, the loss for each mode was not considered at all. This is very important to understand the compensation operation characteristics of APFs. Therefore, this paper proposes the graphical representation of the instantaneous compensation power flow for single-phase APFs considering the instantaneous rectification mode and the instantaneous inversion mode. Three cases are verified in this paper - without compensation, with compensation of the active power 'p' and the fundamental reactive power 'q', and with compensation of only the distorted power 'h'. To ensure the validity of the proposed approach, PSIM simulation is achieved. As a result, we could confirm that the proposed approach was easy to explain the instantaneous compensation power flow considering the instantaneous rectification mode and the instantaneous inversion mode of APFs, also, Total Harmonic Distortion(THD)/Power Factor (P.F) and Fast Fourier Transform(FFT) analysis were compared for each case.