• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.583-584
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• 2015

Energy Storage System(ESS) can be used as several purposes such as uninterruptible power supply (UPS), frequency regulation, maximum load cut, and etc. This paper analyzes and simulates the reclosing operation in distribution system with ESS for frequency regulation and maximum load cut. To solve the effect from ESS, two sequences in reclosing process are added to conventional reclosing. The modelings and simulations of reclosing operation using EMTP/ATPDraw are performed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.226-228
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• 2006

This paper presents the two lossless auxiliary inducors-assisted voltage source type half bridge(single ended push pull:SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliimplemented here is proved from the practical point of view.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.236-241
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• 2001

This paper presents a novel prototype of active voltage-clamping capacitor-assisted edge resonant soft switching PWM inverter operating at a constant frequency variable power (VPCF) regulation scheme, which is suitable for consumer high-power induction-heating cooking appliances. New generation IGBT with a trench gate is particularly improved in order to reduce conduction loss due to its lowered saturation voltage characteristics. The soft switching load resonant and quasi-resonant inverter designed distinctively using the latest IGBTs is evaluated from an experimental point of view.

• Journal of Power Electronics
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• 제14권2호
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• pp.282-291
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• 2014

This paper presents a detailed theoretical analysis and performance assessment of the capacitor voltage balancing strategies for staircase modulated modular multilevel converters (MMC) in terms of the algorithm structures, voltage balancing effect, and switching frequency. A constant-frequency redundancy selection (CFRS) method with minimal switching loss is proposed and the function realization of specific modules of the algorithm is given. This method is simple and efficient in both switching frequency and regulation capacity. Laboratory results show very good agreement with the theoretical analysis and numerical simulations.

• 조명전기설비학회논문지
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• 제22권7호
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• pp.49-57
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• 2008

This paper presents a voltage source type half-bridge series resonant high frequency (HF) inverter for induction heated fixing roller in copy machines. This high-frequency inverter works under zero current soft switching (ZCS) commutation and has wide power regulation range due to employing a pulse density modulation (PDM) scheme. Transient and steady state operating modes of the inverter are presented in this paper together with its PDM-based power regulation system. Experimental operating performances of the developed HF-ZCS inverter as well as power losses and actual efficiency are discussed and compared with computer simulation results.

• 전기전자학회논문지
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• 제20권4호
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• pp.432-434
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• 2016

기존 SIDO(Single Inductor Dual Output) boost converter에서는 전력 사용량의 변화에 맞게 부하에 전하를 공급하는 시간을 바꾸게 된다. 이 때 boost converter의 스위칭 주파수가 변해야 할 정도로 어느 한 부하의 전력 사용량이 크게 바뀔 경우, 나머지 부하에 전하를 공급하는 시간도 바뀌게 된다. 이로 인해 크로스 레귤레이션이 일어난다. 따라서 본 논문에서는 어느 한 부하의 전력 사용량의 변화로 스위칭 주파수가 정수 비로 바뀔 때 나머지 부하에 전하를 공급하는 시간도 같은 정수 비로 변화 시킨다. 이 방법을 전하 복사기법(charge copy)이라 하며 이 효과로 인하여 크로스 레귤레이션이 감소한다. 제안하는 방법의 시뮬레이션 결과로 크로스 레귤레이션이 기존의 방법보다 10.42mV/A 만큼 감소하고, 복원 시간은 39.118us 만큼 작아지는 결과를 보였다.

• 전기학회논문지
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• 제65권4호
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• pp.555-560
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• 2016

Recently, many countries have placed great attention on energy security and climate changes. Governments are promoting the construction of renewable energy projects with regulatory support in Korea. Despite an increasing penetration of renewable resources, however, the photovoltaic and wind power are underutilized due to the endemic problems such as difficulties of output control and intermittent output. The Energy Storage System (ESS) is proposed as a good solution for solving the problems and has been studied in both the private business and the government. However, because of inefficient aspects, the research has been carried out for improving high costs and a small capacity. In addition, the ESS is currently installed for using only one purpose which is frequency regulation or transmission congestion relief such that has an economic limitation. Therefore, methods which are becoming economically justifiable to increase the penetration of the ESS is required. Thus, this paper presents in terms of operation efficiency to improve economic feasibility of the ESS currently used. mainly, there are two aspects for the operation efficiency. Firstly, it is intended to improve the utilization rate through a process that can utilize the ESS for various purposes. It is necessary to be able to use for other purposes by classifying and clustering for increasing the efficiency of availability. The clustering method is proposed to conduct the grouping the ESS. Especially, it is proposed to utilize ESS for frequency regulation service which is the one of ancillary services in the power system. Through case studies, it is confirmed to secure the necessary resources by clustering small size ESS.

• Journal of Power Electronics
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• 제2권1호
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• pp.46-54
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• 2002

In this paper a neural network controller for achieving maximum power tracking as well as output voltage regulation, for a wind energy conversion system (WECS) employing a permanent magnet synchronous generator is proposed. The permanent magnet generator (PMG) supplies a dc load via a bridge rectifier and two buck-boost converters. Adjusting the switching frequency of the first buck-boost converter achieves maximum power tracking. Adjusting the switching frequency of the second buck-boost converter allows output voltage regulation. The on-time of the switching devices of the two converters are supplied by the developed neural network (NN). The effect of sudden changes in wind speed and/ or in reference voltage on the performance of the NN controller are explored. Simulation results showed the possibility of achieving maximum power tracking and output voltage regulation simulation with the developed neural network controllers. The results proved also the fast response and robustness of the proposed control system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.656-659
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• 2001

In this paper a neural network controller for achieving maximum power tracking as well as output voltage regulation, for a wind energy conversion system(WECS) employing a permanent magnet synchronous generator, is proposed. The permanent magnet generator (PMG) supplies a dc load via a bridge rectifier and two buck-boost converters. Adjusting the switching frequency of the first buck-boost converter achieves maximum power tracking. Adjusting the switching frequency of the second buck-boost converter allows output voltage regulation. The on-times of the switching devices of the two converters are supplied by the developed neural network(NN). The effect of sudden changes in wind speed ,and/or in reference voltage on the performance of the NN controller are explored. Simulation results showed the possibility of achieving maximum power tracking and output voltage regulation simultaneously with the developed neural network controller. The results proved also the fast response and robustness of the proposed control system.

• 한국보육지원학회지
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• 제14권3호
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• pp.21-39
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• 2018

Objective: This study was to examined the mediating effect of active emotion regulation and marital quality in the relationships between self-compassion and maternal-fetal attachment. Methods: A questionnaire was administered to 836 pregnant women and the data were analyzed by SPSS21 and M-plus7, and statistical analysis, frequency analysis, and then structural equation modeling were performed. Results: First, self-compassion directly affects maternal-fetal attachment. Second, self-compassion was indirectly influenced by maternal-fetal attachment through active emotional regulation. Third, self-compassion indirectly affects maternal-fetal attachment through marital quality. Fourth, in regards to the relationship between self-compassion and maternal-fetal attachment, active emotional regulation and marital quality were mediated. Conclusion/Implications: we discussed implications for enhancing self-compassion and active emotional regulation and enhancing marital quality to increase the maternal-fetal attachment of pregnant women.