• International Journal of Control, Automation, and Systems
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• 제6권4호
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• pp.495-505
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• 2008

This paper describes modeling Voltage Sourced Inverter (VSI) type Flexible AC Transmission System (FACTS) controllers and control methods for power system dynamic stability studies. The considered FACTS controllers are the Static Compensator (STATCOM), the Static Synchronous Series Compensator (SSSC), and the Unified Power Flow Controller (UPFC). In this paper, these FACTS controllers are derived in the current injection model, and it is applied to the linear and nonlinear analysis algorithm for power system dynamics studies. The parameters of the FACTS controllers are set to damp the inter-area oscillations, and the supplementary damping controllers and its control schemes are proposed to increase damping abilities of the FACTS controllers. For these works, the linear analysis for each FACTS controller with or without damping controller is executed, and the dynamic characteristics of each FACTS controller are analyzed. The results are verified by the nonlinear analysis using the time-domain simulation.

• Journal of Electrical Engineering and Technology
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• 제5권1호
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• pp.79-102
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• 2010

This paper presents exhaustive review of various methods/techniques for coordinated control between FACTS controllers in multi-machine power systems. It also reviews various techniques/methods for optimal choice and allocation of FACTS controllers. Authors strongly believe that this survey article will be very much useful to the researchers for finding out the relevant references in the field of placement and coordination of FACTS Controllers.

• 대한전기학회논문지:전력기술부문A
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• 제55권7호
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• pp.281-289
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• 2006

Advanced controllers among Flexible AC Transmission System(FACTS) devices employ self-commutated switching converters, VSI (Voltage Sourced Inverters), as the synchronous voltage source. Such controllers are SSSC (Static Synchronous Series Compensator), STATCOM (Static Synchronous Compensator) and UPFC (Unified Power Flow Controller). UPFC is series-shunt combined controller. Its series and shunt inverters can be modeled as SSSC and STATCOM but the dependant relation between the inverters is very complex. For that reason, the complexity makes it difficult to develop the UPFC model by simply combining the SSSC and STATOM models when we apply the model for conventional power system dynamic simulation algorithm. Therefore, we need each relevant models of VSI type FACTS devices for power system analysis. This paper proposes a modeling approach which can be applied to modeling of VSI type FACTS devices. The proposed method using Newton-type current injection method can be used to make UPFC, SSSC, and STATCOM models. The proposed models are used for 2-area test system simulation, and the results verify their effectiveness.

• 조명전기설비학회논문지
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• 제18권3호
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• pp.149-155
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• 2004

본 논문에서는 상정사고 해석을 통해 결정된 가장 심각한 단일 선로고장에 대하여 부하차단이나 재급전을 하지 않고, 유연송전기기의 운전만으로 안전도를 향상시켜 이를 극복할 수 있는 방법을 제시하였다. 즉, 직렬, 병렬, 직병렬보상기기 등 유연송전기기의 각 종류별로 정적 안전도 여유를 최대화하고 안전도 지수를 최소화하는 방법을 개발하였고, 이를 통하여 각 유연송전기기의 최적 운전점을 결정하는 방법을 개발하였다. 여기서, 정적 안전도 지수는 선로 조류 및 모선 전압에 관한 안전도를 정량화하여 식으로 나타낸 것이다. 안전도 지수가 작아지면 안전도 여유는 커지는데, 본 논문에서는 안전도 지수를 반복계산법으로 최소화하였다. 본 논문에서는 제안한 방법은 IEEE 57모션개통에 적용하여 제안된 방법의 정당성을 수치적으로 입증하였다.

• 전기학회논문지
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• 제59권3호
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• pp.525-530
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• 2010

Installation of FACTS(Flexible AC Transmission System) device can maximize utilization of existing power facilities and reliability of power system. STATCOM has excellent characteristics in operating cost, maintaining facilities, loss and so on. However, STATCOM has a disadvantage of facility cost over capacity. So it is effective to coordinate STATCOM and existing external bank(capacitor and reactor) and OLTC(On Load Tap Changer). This paper mainly proposes coordinative control method between STATCOM installed within substation and other reactive power resources including Shunt Reactors and Shunt Capacitors and OLTC for voltage stability improvement. The proposed coordinative control method is developed for the STATCOM of Mi-gum substation and the simulation results of EMTP/RV model show the effectiveness of the proposed method.

• 한국정보통신학회논문지
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• 제15권3호
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• pp.624-631
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• 2011

본 논문은 Exciter와 Power System Stabilizer(PSS)를 포함하는 발전기 제어장치와 싸이리스터에 의한 불연속 스위칭 동작을 하는 직렬형 Flexible AC Transmission System(FACTS) 설비인 Thyristor Controlled Static-var Compensator(TCSC)를 포함하는 전력계통의 고유치 해석과 안정도 개선을 위한 고유치 감도계수를 이산 시스템에서의 해석방법을 사용하여 해석하였다. 이산 시스템에서의 해석방법으로는 Resistive Companion Form(RCF) 해석법을 사용하였으며, 상태천이 방정식을 사용하여 감도해석에 필요한 계산 알고리즘을 제시하였고, 연속시스템에서의 해석결과와 비교하였다. TCSC의 스위칭 동작이 고려되지 않는 연속 시스템에서의 해석결과와 달리, 이산 시스템에서의 해석결과 스위칭 동작의 영향으로 제어기 정수에 대한 감도해석 결과가 일정한 방향성을 가지면서 주기적으로 변화하는 것을 알 수 있었다. 또한 중요 진동모드에 대한 제어기정수의 감도계수 값이 연속시스템에서의 해석결과와 달리 싸이리스터의 주기적 스위칭 동작에 의해 다른 값을 가지면서 주기적으로 진동하는 것을 알 수 있었다.

• 전기학회논문지
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• 제59권1호
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• pp.1-8
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• 2010

The ultrafashionable machinery that require high quality electricity power has been daily come into being. Because domestic power system has been larger and more complicated in accordance with raising power demand by power market requirement. Because of these power market situations, The FACTS (Flexible AC Transmission System) which is power transmission system for the next generation to meet flexible supply the power and reliability has been applied. If they, compensators and FACTS, are used inter-efficiently in range that does not affect the stability and a badly influence the security, they might be increase in the voltage stability of system, supply reliability and also achieve the voltage control in a suddenly changed power system. Therefore we describe and suggest on this treatise that a plan for coordination control between UPFC, Shunt elements (Sh. Capacitors & Sh. Reactors) among compensators and also describe the method to keep or control the voltage of power system in allowable ranges. The method follows that, we used characteristics of each equipment, UPFC would be also settled to keep the identified voltage range in change of load bus, Shunt elements also would be settled to supply the reactive power shortage in out of operating range of UPFC to cope actively with change of the power system. As the result of simulation, it is possible to keep the load bus voltage in limited range in spite of broad load range condition. This helps greatly for the improvements of supply reliability and voltage stability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.332-334
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• 2005

This paper presents a dynamic simulation of the unified power flow controller (UPFC) using a current injection method. Flexible AC Transmission System (FACTS) devices give more flexibility of control for security and economic operation of power systems. Diffculties of modeling UPFC in the conventional dynamic simulation programs arise from the fact that the injected voltage by the series inverter is superimposed on the shunt inverter side voltage. A solution can be a current injection method, in which a serial part of UPFC is converted to a parallel equivalent circuit using source transformation, and two current sources affect each other at every time step. To verify efficiency of this method, the proposed model is applied for the transient analysis of an example power system.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.533-540
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• 2017

Distance relay identifies the type and location of fault by measuring the transmission line impedance. However any other factors that cause miss calculating the measured impedance, makes the relay detect the fault in incorrect location or do not detect the fault at all. One of the important factors which directly changes the measured impedance by the relay is series capacitive compensation (SCC). Another factor that changes the calculated impedance by distance relay is fault resistance. This paper provides a method based on the combination of distance and differential protection. At first, faulty transmission line is detected according to the current data of buses. After that the fault location is calculated using the proposed algorithm on the transmission line. This algorithm is based on active power calculation of the buses. Fault resistance is calculated from the active powers and its effect will be deducted from calculated impedance by the algorithm. This method measures the voltage across SCC by phasor measurement units (PMUs) and transmits them to the relay location via communication channels. The transmitted signals are utilized to modify the voltage signal which is measured by the relay. Different operating modes of SCC and as well as different faults such as phase-to-phase and phase-to-ground faults are examined by simulations.