• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.372-378
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• 2012

This paper deals with a 3-phase voltage disturbance generator for a performance test of custom power devices such as dynamic voltage restorers (DVR), dynamic uninterruptable power supplies (UPS), etc. The operating principle of the proposed circuit is described in each mode of voltage sag, swell, outage, and unbalance. The main components of the proposed disturbance generator are silicone controlled rectifier (SCR) thyristors, variable autotransformers, and transformers. Therefore, the disturbance generator can be implemented with a considerably low cost compared to the conventional pulse width modified (PWM) inverter and converter type generators. Furthermore, it has good features of high reliability with simple structure, high efficiency caused by no PWM switching of the SCR thyristors, and easy control with a wide variation range. To verify the validity of the proposed scheme, simulations and experiments are carried out.

• 전력전자학회논문지
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• 제21권1호
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• pp.80-87
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• 2016

This study investigates output voltage variation of a voltage disturbance generator in case of sag and swell modes. The generator uses series transformers and silicon-controlled rectifier thyristors to provide voltage disturbance; consequently, voltage drop at the output terminal is inevitable. On the basis of the analysis, voltage drop increases as the power factor decreases in lagging. Voltage drop is 3.7 [%] at a power factor (lagging) of 0.8. Simulation and experimental results show the validity of the analysis.

• 전기학회논문지P
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• 제64권3호
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• pp.104-110
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• 2015

This paper describes a power quality disturbance generator for the test of a microgrid. The generator provides phase-angle jump as well as voltage sag with simple structure. The main components of the generator are SCR thyristors and transformers, therefore, high reliability and high efficiency can be obtained without switching losses. The operating principle of the proposed scheme is described and the voltage and current characteristics in case of voltage sag with phase-angle jump is analyzed. The usefulness of the proposed topology is verified through simulations and experimental results.

• 전력전자학회논문지
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• 제15권5호
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• pp.411-416
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• 2010

본 논문에서는 변압기 기반 전압변동 발생기의 직렬변압기에 의한 전압강하 특성을 분석하였다. 전압변동 발생기의 회로구성 방식에는 여러 가지가 있으나 본 논문에서는 비교적 비용이 저렴하고 신뢰도가 높은 직렬변압기를 사용한 방식에 대해 다루고자 한다. 직렬변압기에 의한 전압강하는 변압기의 %Z와 부하용량 및 부하역률에 의해 결정된다. 직렬변압기의 설계가 잘못되면 전압강하가 심각하게 발생하여 제대로 된 성능을 확보할 수 없다. 본 논문에서는 10kVA급 전압변동 발생기에 대해 %Z가 4%인 직렬변압기를 사용한 경우 부하역률에 따른 전압강하를 분석하였으며 지상 부하일수록 전압강하가 증가하고 역률이 0.85 지상인 경우 전압강하가 4% 발생함을 시뮬레이션 및 실험을 통하여 확인하였다.

• 전력전자학회논문지
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• 제13권3호
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• pp.163-170
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• 2008

본 논문에서는 DVR 등의 전력품질 개선장치들의 성능시험에 용이하게 사용하기 위하여 제안한 3상 전압변동 발생기에 대하여 선형뿐만 아니라 비선형 부하에서도 동작이 가능함을 보이는 스위칭 특성해석을 하였다. 선형 부하의 경우는 전류가 연속이므로 전압변동 발생기를 구성하는 SCR 사이리스터의 자연전류(natural commutation)가 용이하게 발생하지만, 비선형 부하의 경우는 전류 불연속 모드 동작이 발생하여 SCR 사이리스터의 원활한 스위칭이 이루어질 수 없는 경우도 있다. 따라서 비선형 부하 시 전류 불연속 구간에서의 SCR 사이리스터의 스위칭 패턴을 분석하여 전압 새그(sag), 스웰(swell), 순간정전(outage), 전압불평형(voltage unbalance) 동작이 선형에서와 동일하게 발생되는 조건을 파악하였다. 각각의 기능을 발생시키는 원리와 동작 특성을 해석하였으며 시뮬레이션과 실험을 통하여 성능을 확인하였다. 본 논문에서 다룬 전압변동 발생기는 전원 외란 발생을 낮은 비용으로 구현해 낼 수 있고 구조와 제어가 간단하여 전력품질 개선과 관련된 연구를 하는데 용이하게 활용될 것으로 기대한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.218-220
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• 2007

A new 3-phase voltage disturbance generator is proposed. The voltage drop of the conventional generator in normal mode can be reduced significantly. The output voltage of the proposed generator is constant in normal mode and the efficiency of the series transformer is improved. The proposed generator has good feature of simple structure, cost effective implementation, high reliability, high efficiency, and easy control. The usefulness of the scheme is verified through simulation and experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.120-122
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• 2007

A new power quality disturbance generator is proposed. The proposed scheme overcomes the problem of voltage drop of the conventional generator in normal mode. Therefore, the output voltage of the proposed generator is constant in normal mode and the efficiency of the series transformer is improved. The proposed generator has good feature of simple structure, cost effective implementation, high reliability and easy control. The usefulness of the scheme is verified through simulation and experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1254-1256
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• 2004

This paper deals with a novel 3-phase power quality disturbance generator. The proposed generator can be applied to the performance that of custom power devices. Voltage sag, swell and outage are provided by the generator. The control scheme for the disturbance generation is simple, and hardware setup is cost effective, compared with conventional scheme. The operating principle of the generator is described and the usefulness verified through simulation with 10KVA power rating.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.552-554
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• 2005

This paper deals with a simple structured voltage disturbance generator for power quality improving devices. The proposed generator can be applied to the performance test of custom power devices. Voltage sag, swell, outage, unbalance and phase jump after outage are provided by the generator. The improving phase jump operating principle of the generator is described and analysed. The usefulness of the generator is verified through simulation.

• 전기학회논문지P
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• 제67권2호
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• pp.57-62
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• 2018

A brush-less type synchronous generator driven by an internal-combustion engine is used for emergency electric source. These types of generators have to maintain a certain range of output voltage even under the sudden load change conditions such as full load application and removal. This paper describes a method for suppressing the output voltage of a synchronous generator that operates excessively when the load fluctuates. The method used in this paper is a feedforward control method in which the main voltage control consists of a feedback loop using a typical PID controller and the load current is detected as a disturbance element and compensated directly. A feedforward system is constructed in which the load current is regarded as disturbance, and the appropriate feedforward controller configuration and parameters are found through simulation. Finally, it can be seen through the experiment that the feedforward control is performed properly. It can be seen that the generator terminal voltage is recovered to the steady state in a short period of time as compared with the existing PID control method even when the entire load of the generator is changed.