• 대한전기학회논문지:전력기술부문A
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• 제53권11호
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• pp.610-618
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• 2004

With the development of industry and the improvement of living standards, better quality in power electric service is required more than ever before. Under these circumstances, to deliver reasonable voltage regulation methods in distribution systems need to be developed. So, This paper deals with optimal introduction of the line voltage regulator (SVR : Step Voltage Regulator) in power distribution systems. First, This paper investigates characteristics of SVR and performs economic evaluation of SVR's introduction by using Present Worth Method. This paper, also suggests proper location and optimal voltage regulation algorithm. In order to deliver suitable voltages to as many customers as possible, the optimal sending voltage of SVR should be decided by the effective operation of voltage regulators at the distribution feeders. The simulation results using a model distribution system and real distribution systems show that the proposed methods can be a practical tool for the voltage regulation in distribution systems.

• Journal of Power Electronics
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• 제15권6호
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• pp.1601-1608
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• 2015

This paper presents a PQ control strategy for micro grid inverters with axial voltage regulators. The inverter works in the voltage-controlled mode and can help improve the terminal power quality. The inverter has two axial voltage regulators. The 1st regulator involves the output voltage amplitude and output impedance, while the 2nd regulator controls the output frequency. The inverter system is equivalent to a controllable voltage source with a controllable inner output impedance. The basic PQ control for micro grid inverters is easy to accomplish. The output active and reactive powers can be decoupled well by controlling the two axial voltages. The 1st axial voltage regulator controls the reactive power, while the 2nd regulator controls the active power. The paper analyses the axial voltage regulation mechanism, and evaluates the PQ decoupling effect mathematically. The effectiveness of the proposed control strategy is validated by simulation and experimental results.

• Journal of Power Electronics
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• 제11권6호
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• pp.880-889
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• 2011

In this paper, a novel Active Voltage Quality Regulator (AVQR) topology with a thyristor rectifier and an adaptive dclink voltage control strategy are proposed. The proposed AVQR can efficiently mitigate the long duration variations (e.g. undervoltages/overvoltages), voltage imbalances and voltage harmonics. Compared with conventional AVQRs, it can regulate the load voltage very well with a much lower dc-link voltage. This is accomplished by replacing the diode rectifier with a thyristor rectifier. Moreover, its dc-link voltage can vary with the deviations of the supply voltage through the proposed adaptive dc-link voltage control strategy. All of these contribute to its significantly higher efficiency for online operating, which is very important and attractive for many applications. The proposed topology and control strategy are theoretically analyzed in detail. Simulation results are also provided in the paper. Finally, the feasibility and effectiveness of the proposed method are verified by means of experimental results from a 2kVA prototype. Both of the simulation and experimental results show that the proposed AVQR can achieve a much higher efficiency and similar regulation performance when compared with the conventional ones.

• Journal of Power Electronics
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• 제12권4호
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• pp.664-676
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• 2012

A phase shift algorithm based on the closed-loop control of dc-link voltage implemented on a series active voltage quality regulator (AVQR) is proposed in this paper. To avoid pumping-up the dc-link voltage, a general phase shift compensation strategy is applied. The relationships among the operation variables are discussed in detail, which is very important for guiding the design of both the main circuit and the control system. Then on the basis of an investigation of the dc-link voltage pumping-up from viewpoint of the active power flow, a novel phase shift control method based on the closed-loop of the dc-link voltage is proposed. This method can adjust the phase of the output voltage gradually and automatically according to the dc-link voltage variation without introducing a phase jump. The effectiveness of the proposed strategy is verified through simulations of a single-phase 5kVA prototype and laboratory experiments on both a single-phase 5kVA and a three-phase 15kVA prototype.

• 조명전기설비학회논문지
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• 제27권11호
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• pp.69-75
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• 2013

This paper proposes a new algorithm for the optimal placement of a step voltage regulator(SVR) in distribution system with Distributed Generators(DG) using a Particle Swarm Optimization(PSO). The objective function of this algorithm is to find optimal placement for minimum loss while maintaining each node voltage fluctuations within upper and lower limits. In the objective function of proposed algorithm, the deviations to reference voltage and the distribution loss are considered. To verify effectiveness of the proposed method, simulation is implemented using MATLAB.

• 한국산학기술학회논문지
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• 제12권6호
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• pp.2698-2706
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• 2011

본 논문에서는 기존의 고압배전선로에 설치되어 운용되고 있는 선로전압조정장치(Step Voltage Regulator, 이하 SVR)의 최적 전압조정 알고리즘을 제시하고 이를 이용하여 수용가전압을 평가할 수 있는 최적 평가시스템을 제시한다. 현재 SVR은 일정전압 송출방식을 사용하고 있지만, 대규모의 태양광, 풍력 등의 분산전원이 배전계통에 도입되는 경우, 전압품질[과전압/저전압] 문제점을 발생시킬 수 있다. 따라서 본 논문에서는 선로전압조정장치의 LDC운용에 필수적인 정정치를 계산하기 위하여, 비선형 최적화수법인 선형회귀법을 사용하여 선로전압조정장치의 최적 운용 알고리즘을 제시하였고, 제안한 알고리즘을 바탕으로 평가시스템을 제작하여, 분산전원의 타입과 연계용량에 따라 다양한 시뮬레이션을 수행하여 제안한 알고리즘의 유효성을 확인하였다.

• Journal of Power Electronics
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• 제13권2호
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• pp.256-263
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• 2013

This paper presents an IHQRR (Integrated High Quality Rectifier Regulator) BIFRED (Boost Integrated Flyback Rectifier Energy Storage DC-DC) converter fed BLDC (Brushless DC) motor drive. A reduced sensor topology is derived by utilizing a BIFRED converter to operate in a dual DCM (Discontinuous Conduction Mode) thus utilizing a voltage follower approach for the PFC (Power Factor Correction) and voltage control. A new approach for speed control is proposed using a single voltage sensor. The speed of the BLDC motor drive is controlled by varying the DC link voltage of the front end converter. Moreover, fundamental frequency switching of the VSI's (Voltage Source Inverter) switches is used for the electronic commutation of the BLDC motor which reduces the switching losses in the VSI. The proposed drive is designed for a wide range of speed control with an improved power quality at the AC mains which falls within the recommended limits imposed by international power quality standards such as IEC 61000-3-2.

• 전기학회논문지
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• 제58권7호
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• pp.1263-1269
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• 2009

Stable and sustainable power supply means maintaining a certain level of power quality and service while securing energy resource and resolving environmental issues. Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. It is known that voltage violation is the most important constraint for load variation and the maximum allowable DG. In distribution system, sending voltage from distribution substation is regulated by ULTC (Under Load Tap Changer) designed to maintain a predetermined voltage level. ULTC is controlled by LDC (Line Drop Compensation) method compensating line voltage drop for a varying load, and the sending voltage of ULTC calls for LDC parameters. The consequence is that the feasible LDC parameters considering variation of load and DG output are necessary. In this paper, we design each LDC parameters determining the sending voltage that can satisfy voltage level, decrease ULTC tap movement numbers, or increase DG introduction. Moreover, the maximum installable DG capacity based on each LDC parameters is estimated.

• 전기전자학회논문지
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• 제5권2호
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• pp.146-152
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• 2001

본 논문에서는 배전 계통에서 전압 파형 개선을 위하여 배전용 정지형 보상기(DSTATCOM)의 제어 기법 2가지를 보였다. 1선 지락 사고 시에 제시한 방법을 이용한 시뮬레이션을 통해 선로 전압 파형이 개선됨을 알 수 있다. 또한 비제어 및 PI 제어와 LQR 제어를 비교하였다. 요구되는 응답 특성 및 제어 효과에서 LQR 제어가 우수함을 보이고 PSCAD/EMTDC을 이용하여 검증하였다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제7권1호
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• pp.1-11
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• 2007

This paper presents a derating design approach for reliability improvement of a regulator IC. The IC is usually used in SMPS. The main failure mechanism of interest is voltage drop due to the package delamination mainly caused by two stresses, i.e. temperature and current. The lifetime under stresses is modeled as a function of stresses and time using accelerating life testings. Quantitative and qualitative variation in lifetime according to stress variations are investigated using the modeled lifetime. Stress levels would be determined to achieve required reliability levels in the aspect of derating design for reliability.