• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.332-334
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• 2008

The matrix-type superconducting fault current limiter (SFCL) using YBCO thin film consists of the trigger and current-limiting parts. We fabricated the matrix-type SFCL with the integrated current limiting modules. we carried out the experiment of matrix-type SFCL with the integrated current limiting modules connected in series or parallel. We saw current characteristics due to ratio of change the shunt resistance and turns. We confirmed that the difference of critical current between superconducting units was decreased by increment of current flowing into the reactor which applied the magnetic field into the superconducting units..

• Journal of Power Electronics
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• 제7권3호
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• pp.233-237
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• 2007

This paper deals with the new HVDC interaction which was observed in the Jeju-Haenam HVDC system. The interaction is not from a system malfunction or controller loop problem but from the change of AC network scheme and the network operating condition. We have found that the interaction is caused by the voltage oscillation between synchronous compensator and HVDC shunt reactor. We analyzed the cause of the interaction and suggested a solution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1075-1077
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• 1993

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.286-290
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• 2007

In this paper, a new algorithm based on sensitivity method for alleviating overloads in power networks is presented to find the switching branches effectively. Preferentially the switching of shunt reactive devices such as shunt reactor and shunt capacitors is performed. If overloads are not eliminated, the ranking of switching branches is calculated according to the algorithm based on sensitivity method and the switching of the ranked branches is performed in the order of ranking until overloads are eliminated. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus test system.

• 대한전기학회논문지
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• 제31권11호
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• pp.133-140
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• 1982

In recent years, a number of thyristor-controlled shunt compensators have been used in industrial and utility systems for phase balancing, power-factor correction and flicker reduction. This paper describes a simple and basic control scheme and circuits for shunt compensator with a fixed capacitor and thyristor-controlled reactor. Feedforward-control scheme is applied, and compensating currents are computed from the symmetrical components of the disturbed system. A 8 bit microprocessor is used for the computation of the compensating currents as well as for the measurements of the symmetric components. A 3-phase 1 KVA compensator is developed and a good reduction of the unbalance factor of the power source is achieved using it.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권12호
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• pp.664-669
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• 2002

In this paper the method to determine tire optimal switching instants in order to reduce the transient surges during switching not relevant to the neutral treatment of shunt reactors is presented. This method consists of the following two steps. First, the instants of the voltage peaks between the contacts of each poles and the voltage magnitude as well as the moments of the current zero crosses were found out analytically. Next, the instants of the contact touches or separations were determined in consideration of the rate of decrease of dielectric strength or a circuit breaker and the variation of the its operating time. The results obtained from the EMTP(Electromagnetic Transient Program) analysis studies show that the making instants are established at the peak voltage of each three poles for any conditions of a neutral point and the possible upper limited values of inrush currents due to the variation of the mechanical operating time can be estimated.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.201-203
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• 2005

A new 3-phase line-interactive UPS(Uninterruptible Power Supply) system with parallel-series active power-line conditioning capability using AC line reactor and two four-leg PWM VSCs(Voltage Source Converters) was introduced recently, In this paper, the strategy of voltage control in suggested UPS system is explained. The objective of proposed voltage controllers in parallel(shunt) and series PWM VSC is to guarantee satisfactory characteristics in steady state and transient state.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.689-697
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• 2012

This paper proposes a new coordinated voltage control scheme between STATCOM (Static Synchronous Compensator) and reactive power compensation devices, such as shunt elements(shunt capacitor and shunt reactor) and ULTC(Under-Load Tap Changer) transformer in a local substation. If STATCOM and reactive power compensators are cooperatively used with well designed control algorithm, the target of the voltage control can be achieved in a suddenly changed power system. Also, keeping reactive power reserve in a STATCOM during steady-state operation is always needed to provide reactive power requirements during emergencies. This paper describes the coordinative voltage control method to keep or control the voltage of power system in an allowable range of steady-state and securing method of momentary reactive power reserve using PSS/E with Python. In the proposed method of this paper, the voltage reference of STATCOM is adjusted to keep the voltage of the most sensitive bus to the change of loads and other reactive power compensators also are settled to supply the reactive power shortage in out range of STATCOM to cope with the change of loads. As the result of simulation, it is possible to keep the load bus voltage in limited range and secure the momentary reactive power reserve in spite of broad load range condition.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1072-1077
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• 2006

본 논문은 AC 라인 리액터와 2개의 4레그 PWM 전압형 컨버터를 사용하여 병렬 및 직렬 능동필터 기능을 가지는 새로운 3상 Line-Interactive UPS 시스템을 제안하고 전압제어 방식을 설명한다. 제안하는 UPS 시스템의 병렬 및 직렬 PWM 전압형 컨버터에서 전압제어의 목적은 정상상태 및 과도상태에서 만족스러운 동작 특성을 보장하는 것이다.

• 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.