• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.609-611
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• 1996

Zero-Cross Detector makes pilot signal to control the power to CEDM(Control Element Drive Mechanism). Existing Zero-Cross Detectors has had a problem which can cause unexpected reactor trip resulted from fluctuating frequency of input signal coming from M/G Set. The existing Zero-Cross Detector can't work properly when power frequency is varying because it was designed to work under stable M/G Set operation, and produces wrong pilot signal and output voltage. In this report the Zero-Cross Detector is improved to resolve voltage fluctuating problem by using new devices such as digital noise filtering circuit, variable cycle compensator and alarm circuit. And through the performance verification it shows that new circuit is better than old one. If suggested detector is applied to plant, it is possible to use it under House Load Operation because stable voltage can be generated by new Zero-Cross Detector.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.356-358
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• 2001

Voltage sags are known as a serious problem causing mal-operation of equipment, process controllers and adjustable-speed drives. We understand problems of the voltage sag that have a bad effect to the load and then we design for a new model of the compensator. We accomplished system modeling for both sensorless part and sensing part, and compare the merits and demerits of both.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.262-265
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• 2001

최근 전력계통의 과부하, 전압안정도 등의 문제에 대한 해결책으로 FACTS (Flexible AC Transmission Systems)가 대두되고 있다. FACTS 설비에는 TCSC (Thyristor-Controlled Series Capacitor), SSSC (Static Synchronous Series Capacitor)와 같은 직렬 기기와 SVC(Static Var Compensator), STATCOM(STATic COMpensator) 와 같은 병렬기기 그리고, 본 논문에서 다루는 UPFC와 같은 직 병렬기기로 나누어진다. UPFC는 SSSC와 STATCOM을 결합한 형태로 유 무효전력을 동시에 보상할 수 있는 FACTS 기기이다. 본 논문에서는 한전 계통의 전압안정도 향상과 과부하 해소를 위해 강진S/S에 설치예정인 80MVA UPFC의 하드웨어 특성과 주변계통의 특성을 소개하고, UPFC와 한전 계통의 연계방안과 시험방안을 설명한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.903-908
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• 1998

This paper aims at investigating the characteristics of the operating modes of two-module Thyristor Controlled Series Compensator (TCSC) in a power transmission system. The operating modes of two-module TCSC are defined, analyzed and compared to those of single-module TCSC are defined, analyzed and compared to those of single-module TCSC. The load flow program, the stability calculation program and Electro Magnetic Transient Program (EMTP) simulation of a TCSC power transmission system are developed for the performance evaluation of two-module TCSC as a power flow controller. In the process of the simulation study, the potential problem areas of the TCSC power transmission system are identified.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.483-494
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• 2002

In this thesis an optimal design technique of fuzzy logic controller using the real variable elitist genetic algorithm(RVEGA) as a supplementary control to Static Var Compensator(SVC) in order to damp oscillation in an AC-DC Dower system was proposed. Fuzzy logic controller is designed self-tuning shape of fuzzy rule and fuzzy variable using genetic algorithm based on natural selection and natural genetics. To verify the robustness of the proposed method, considered dynamic response of system by applying a load fluctuation.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.192-201
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• 1997

The feedback control scheme of the pressure control system of the rear wheel steering gear which has relatively large volume and sprung load was built up in order to improve th response characteristic of the system. The control algorithm chosen was a feedback compensator joined by a feedfoward compensator and the model matching method was used in the process of control system design. The structures and properties of the reference models were inspected and the parameters of the controller were decided. The improvement of the response characteristic of the pressure control valve by means of the feedback control is affirmed. Particularly, when the order of the system model is higher than the 2nd order, the effectiveness of the feedback control on the improvement of the response characteristic of the valve is distinct. And the convenience of the model matching method is the process of control system design is confirmed as well.

• 전기학회논문지
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• 제62권3호
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• pp.417-423
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• 2013

The load of electric railroad can generate voltage fluctuation in the electric railway system because of high speed of the electric railroad and frequent movement and stop. This voltage fluctuation of electric railway system can cause not only voltage imbalance but also harmonic in the utility grid. Therefore the electric railroad system is in need of the reactive power compensation, such as static synchronous compensator (STATCOM) and static var compensator (SVC). Especially, the battery energy storage system (BESS) can control the real and reactive power at the same time. In this paper, the electric railway system using BESS has been modeled to show its voltage compensation effect using Matlab/Simulink.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권6호
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• pp.402-408
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• 2004

This paper proposes the novel V/f control method to improve the stability of a V/f controlled induction motor drive system. The conventional V/f control method used in the proposed V/f control method is a vector-based method that is slightly different from the existing conventional V/f control method. The proposed control method uses a dynamic current compensator to improve the stability of a V/f controlled induction motor drive system. This proposed method is easy to implement and completely eliminates the motor oscillation phenomenon causing the instability of a V/f controlled induction motor drive system, especially when the system is driven near the resonant frequency in steady-state with light load. Additionally, this paper analyzes theoretically the instability of a V/f controlled induction motor drive system and shows the validity of the Proposed V/f control method through simulation and experimental results.

• 전기학회논문지
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• 제57권8호
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• pp.1377-1382
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• 2008

DSTATCOM(distribution static compensator) is one of the custom power devices, and protects a distribution line from unbalanced and harmonic current caused by non-linear and unbalanced loads. Researches about DSTATCOM are mainly divided two parts, one is the calculation of compensation current and the other part is the current control. Conventional researches use a LPF(low pass filter) to eliminate ripple component at the calculation of compensation current. But this method has a problem that LPF's characteristics restrict the compensation performance of instantaneous active and reactive power. This paper proposes a calculation of compensation current using state observer that can be a counterproposal of conventional methods using LPF. Improved performance of instantaneous active and reactive power compensation was shown by experiments.

• Journal of Power Electronics
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• 제11권3호
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• pp.375-380
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• 2011

A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using Gate Turn Off (GTO) power semiconductor devices employed for reactive power control. The operation principal is similar to that of a synchronous condenser. A typical application of a STATCOM is voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. This paper presents the modeling of STATCOM with twenty four pulse three level VSC and Type-1 controller to regulate the reactive current or the bus voltage. The performance is evaluated by transient simulation. It is observed that, the STATCOM shows excellent transient response to step change in the reactive current reference. While the eigenvalue analysis is based on D-Q model, the transient simulation is based on both D-Q and 3 phase models of STATCOM (which considers switching action of VSC).