• 대한전기학회논문지:전력기술부문A
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• 제53권9호
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• pp.494-499
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• 2004

This paper presents to compute the power economic dispatch, an optimal power flow (OPF) computation algorithm, considering the load power factor limits constraint in developed. Efficient reactive power planning enhances economic operation as well as system security. Accordingly, an adequate level of power factor limits for the load busesshould be evaluated for economic operation. In this paper, the ranges of acceptable load power factors are portrayed as bandwidths of load power factor expressed as a function of load level. The load power factor limits are included and described into the OPF's objective function. The method Proposed is applied to IEEE 26 bus system.

• 전기학회논문지P
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• 제64권3호
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• pp.159-163
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• 2015

Recently squirrel cage induction generator has been steadily applied to many small hydro power plants. Induction generator needs a reactive power for magnetization. The reactive power of induction generator is being supplied from the supply side mostly. The use of induction generators in the power distribution grid can affect the power factor. The power factor of induction generator is fixed already during production. The power factor in the distribution system is due to the increase or decrease of the load rather than due to the induction generator. In this study, we analyzed that how the increase or decrease of D/L load impacts at the change of power factor and power flow.

• 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.

• 전자공학회논문지
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• 제53권7호
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• pp.121-127
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• 2016

본 논문에서는 고조파로 전압과 전류가 왜곡된 상황에서 정확하게 기본파의 역률을 측정할 수 있는 방법을 제안한다. 제안한 역률 계측 방법에서는 전압과 전류를 DQ회전좌표계로 변환한 후 유효전력과 무효전력을 계산하여 역률값을 구하게 된다. 기존의 역률 계측방법과 제안한 방법을 수식적으로 비교하여 제시하고, 제안한 방법은 전압과 전류 모두 고조파 왜곡된 상황에서도 기본파의 역률을 정확하게 계측할 수 있는 것을 MATLAB을 이용한 모의실험에서 확인한다. 제안한 역률 계측방법을 자동역률제어장치에 적용할 경우 고조파 왜곡 환경에서 역률 보상 성능을 최대화 할 수 있다. 그 결과 수용가에서는 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.

• 전기학회논문지
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• 제66권3호
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• pp.593-598
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• 2017

Induction generator is always required reactive power in order to generate a rotating magnetic field as an inductive load. The reactive power must be continuously supplied to the induction generator as well as load of distribution system from the power supply side. So the power factor of the power supply side during the induction generation operation is low. Condenser is installed in order to raise the low power factor of the induction generator. Switching transients occurs when the power supply of the capacitor is turned on in order to ensure the low power factor. When using the reactor in series with the capacitor in order to reduce the influence of switching transient, it can affect the reactive power by the condenser voltage rises. In this study, we analyzed the operating characteristics for power and power factor of induction generator in accordance with the presence or absence of the application of the serial reactors for switching transients reduction of the condenser and the condenser for power factor correction.

• 전기학회논문지
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• 제65권7호
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• pp.1311-1315
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• 2016

Induction motor requires a rotating magnetic field for rotation. Current required to generate the rotating magnetic field is immediately magnetizing current. This magnetizing current is associated with the reactive power. Induction motor is always required reactive power. If reactive power is supplied only to the power supply side, the power factor is low. Therefore, it is to compensate the power factor by connecting capacitors in parallel to the motor terminal. If the capacitor current is greater than the magnetizing current of the motor, there is a possibility that the self-excitation occurs. High voltage generated by the self-excitation leads to insulation failure on the motor. So it is necessary to calculate the power factor correction capacitor capacity the most suitable to the extent that the magnetizing current does not exceed the capacitor current. In this study, we first computed the magnetization current and the reactive power of the induction motor and then calculates a limit of the maximum power factor by comparing the magnetizing current and the capacitor current installed in order to achieve the target power factor.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.499-500
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• 2008

In this paper, we design and implement the monolithic power factor correction IC for system power modules using a high voltage(50V) CMOS process. The power factor correction IC is designed for power applications, such as refrigerator, air-conditioner, etc. It includes low voltage logic, 5V regulator, analog control circuit, high-voltage high current output drivers, and several protection circuits. And also, the designed IC has standby detection function which detects the output power of the converter stage and generates system down signal when load device is under the standby condition. The simulation and experimental results show that the designed IC acts properly as power factor correction IC with efficient protective functions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.480-482
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• 2005

In this paper, utilization of load duration curves is presented for analyzing the effect of load power factor and determining the value of load power factor effectively. In addition, the power factor sensitivity of generation cost and integrated costs including voltage variation penalty cost are used for determining the value of the load power factor from the point of view of voltage regulation and economic investment. It is shown through the application to the KEPCO power system that the load power factor can be enhanced effectively and appropriately using the load duration curve.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.147-150
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• 2002

HPSL(High Pressure Sodium lamp)have attracted much attention in recent years, because they offer high luminous efficiency and very long life. Recently, AC-DC converters have been widely as power factor improvement circuits in the power conversion equipment An application of the ZVT-PWM(Zero Voltage Transition Pulse Width Modulation) boost converter, which has great advantage on miniaturization and high power density, to the power factor improvement circuit of the HPSL inverter are described to identify the power factor correction characteristics of the inverter. In this paper the series-parallel resonant inverter(electronic ballast) for driving a HPS lamp is discussed. Finally, a power factor corrector is cascaded in front of the electronic ballast. Consequently, a high power factor above 0.99 and low THD on the line current can be achieved.

• 수산해양기술연구
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• 제16권1호
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• pp.43-47
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• 1980

The author designed and tested the high sensitive three-phase power factor meter and relay circuit, and dealt with the circuit to detect the phase of the current and the voltage. An operational amplifier comparator circuit and two single-phase transformers are used to control and detect the phase angle between the current and the voltage. The results obtained are as follows: 1. Converting the sine wave input current into the constant amplitude rectangular wave form by using a transistor chopper circuit, the power factor can be measured precisely over the load current of 0.08 A. 2. Using the moving coil type current meter, the power factor meter can be read in uniform . scale all over the range. 3. Using the three-phase power factor meter, the power factor relay which works at any power factor can be made.