• 한국전자통신학회논문지
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• 제11권10호
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• pp.963-968
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• 2016

논문에서는 도시철도의 변전소의 최대수요전력을 줄이기 위한 새로운 방법으로 OLTC(:On Load Tap Changer)를 갖는 변압기의 사용을 제안한다. 국내의 대부분의 도시철도는 전동차에 필요한 전력을 다이오드 방식으로 정류하며 DC 1500[V]로 공급한다. 변전소가 병렬로 연결되어 있기 때문에 수전전압이 상승하면 정류기 전압도 상승하게 되고 변전소의 최대전력도 증가하게 된다. 시뮬레이션 결과를 통해 본 논문에서 제안하는 방법이 최대수요전력의 증가를 상당히 제한할 수 있음을 보인다.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2211-2220
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• 2015

This paper analyzes multiple active management (AM) techniques of active distribution network (ADN), and proposes an optimal coordination model of intermittent distributed generation (IDG) accommodation considering the timing characteristic of load and IDG. The objective of the model is to maximize the daily amount of IDG accommodation under the uncertainties of IDG and load. Various active management techniques such as IDG curtailment, on-load tap changer (OLTC) tap adjusting, voltage regulator (VR) tap adjusting, shunt capacitors compensation and so on are fully considered. Genetic algorithm and Primal-Dual Interior Point Method (PDIPM) is used for the model solving. Point estimate method is used to simulate the uncertainties. Different scenarios are selected for the IDG accommodation capability investigation under different active management schemes. Finally a modified IEEE 123 case is used to testify the proposed accommodation model, the results show that the active management can largely increase the IDG accommodation and penetration.

• 한국산업정보학회논문지
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• 제17권7호
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• pp.119-125
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• 2012

본 논문은 변전소 내에서 취득된 데이터만을 이용하여 전계통 전압안정도를 확보하기 위한 실시간 변전소내 OLTC(On-Load Tap Changer)와 S.S(Switched Shunt)와의 협조제어 알고리즘을 제안하고자 한다. 전압레벨을 일정한 값으로 유지시키기 위해서 동작하는 OLTC의 제어를 잘못하게 된다면 오히려 계통의 안정도(전압안정도) 를 해치는 결과를 나타낼 수 있다. 이 논문에서는 단일 변전소에서 취득된 데이터만으로 전체 시스템의 상태를 판단할 수 있는 Z-index를 이용하였다. Z-index를 이용하여 시스템을 normal 상태와 abnormal 상태로 구분하였고, 각 상태에 따른 협조제어 알고리즘을 제안하였다. 알고리즘 검증을 위해서 Hypersim과 matlab simulink를 이용하였다.

• 대한전기학회논문지:전력기술부문A
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• 제55권6호
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• pp.242-248
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• 2006

This paper proposes a coordinated control method for under-load tap changers (ULTCs) with shunt capacitors to reduce the operation numbers of both devices. The proposed method consists of two stages. In the first stage, the dispatch schedule is determined using a genetic algorithm with forecasted loads to reduce the power loss and to improve the voltage profile during a day. In the second stage, each capacitor operates according to this dispatch schedule and the ULTCs are controlled in real time with the modified reference voltages considering the dispatch schedule of the capacitors. The performance of the method is evaluated for the modified IEEE 14-bus system. Simulation results show that the proposed method performs better than a conventional control method.

• KIEE International Transactions on Power Engineering
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• 제4A권4호
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• pp.207-213
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• 2004

In this paper, the on-line volt/var control algorithms of the Load Tap Changer (LTC) transformer and Shunt Capacitor (SC) are proposed for distribution volt/var compensation. In the existing volt/var control of the distribution substation, the feeder voltage and reactive power demand of the distribution are mainly controlled by the LTC transformer tap position and on/off operation of the Sc. It is very difficult to maintain volt/var at the distribution networks within the satisfactory levels due to the discrete operation characteristics of the LTC and SC. In addition, there is the limitation of the LTC and SC operation times, which affects their functional lifetimes. The proposed volt/var control algorithm determines an optimal tap position of the LTC and on/off status of the SC at a distribution substation with multiple connected feeders. The mathematical equations of the proposed method are introduced. A simple case study is performed to verify the effectiveness of the proposed method.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2006년도 High Temperature Superconductivity Vol.XVI
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• pp.98-98
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• 2006

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.330-336
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• 2009

This paper proposes an on-line voltage management and control solution for a distribution system which can improve the efficiency and accuracy of existing off-line work by collecting customer voltage on-line as well as the voltage compensation capability of the existing ULTC (Under Load Tap Changer) operation and control strategy by controlling the ULTC tap based on pattern clustering and recognition. The proposed solution consists of an ADVMD (Advanced Digital Voltage Management Device), a VMS (Voltage Management Solution) and an OLDUC (On-Line Digital ULTC Controller). An on-line voltage management emulator based on multi-thread programming and the shared memory method is developed to emulate on-line voltage management and digital ULTC control methodology based on the on-line collection of the customer's voltage. In addition, using this emulator, the effectiveness of the proposed pattern clustering and recognition based ULTC control strategy is proven for the worst voltage environments for three days.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.710-713
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• 1992

An AVR for OLTC controls motor tap in transformer in order to supply constant power source. Recently for society which is higher informative and more automatic, in our research, the digital AVR for OLTC is developed that can perform more functions and higher functions ( mesurement, display, protection, control ) using microprocessor in a different control method than the conventional AVR. The experiment result is also present.

• Journal of Electrical Engineering and Technology
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• 제2권2호
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• pp.152-156
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• 2007

This paper proposes a method for real-time control of both capacitors and ULTC in a distribution system to reduce the total power loss and to improve the voltage profile over the course of a day. The multi-stage consists of the off-line stage to determine dispatch schedule based on a load forecast and the on-line stage generates the time and control sequences at each sampling time. It is then determined whether one of the control actions in the control sequence is performed at the present sampling time. The proposed method is presented for a typical radial distribution system with a single ULTC and capacitors.

• 한국초전도ㆍ저온공학회논문지
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• 제9권1호
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• pp.67-71
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• 2007

HTS transformers which have been developed until now had only fundamental structures. Among the auxiliary functions of conventional transformers, voltage regulating is the most important one. For the voltage regulation, conventional transformers are equipped with on load tap changers (OLTCS). In this paper, we describe the possibility of the HTS transformer with OLTC. For the case study, we designed a single phase 33 MVA HTS transformer with OLTC. It is one of three individual HTS transformers which composes a 3 phase, 100 MVA transformer. It is expected to substitute for a 3 phase, 60 MVA conventional transformer in Korea. The parameters of an HTS transformer are varied due to the gap length between primary and secondary windings. The length was decided for the transformer to have the impedance of 12 %. Its size was limited to the one of the conventional transformer. The characteristics of the HTS transformer were analyzed in both case of having OLTC and not.