• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.81-89
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• 2004

AC electric railroad system receives its power from 3-phase transmission system. Since trainloads are moving continuously, the voltages for the single load fluctuate in the train garage, and moreover, the fluctuating voltages generate high-order harmonics. This means the difficulty in maintaining power quality in the power system. Therefore, in this paper, the adequacy of SVC application is investigated for the train garage in KNR(Korean National Railroad). Voltage drop, voltage regulation, and unbalanced voltages are assessed in the train garage for the condition of power system both with svc and without SVC. In this paper, PSCAD/EMTDC is used for the above assessment items, and the results are compared with ones which was already designed in the field in practice for the train garage. As a result, the train garage using SVC improves power quality.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.230-232
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• 2000

To improve the voltage profile of the load bus, it is important that the coordinated controls among the reactive power compensators at the distribution substation. However, the conventional control scheme of the Under Load Tap Changer (ULTC) is not proper for coordinate control with Static Var Compensator (SVC). This paper proposes a new control model for ULTC and a new coordinated control scheme between ULTC and SVC. The numerical simulation verifies that the proposed system could improve the voltage profile on the load bus and could decrease the number of ULTC tap operation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.1
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• pp.10-15
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• 2003

This paper presents the digital computer performance evaluations of the three-phase self-excited induction generator (SEIG) driven by the variable speed prime mover such as the wind turbine using the nodal admittance approach steady-state frequency domain analysis with the experimental results. The three-phase SEIG setup is implemented for small-scale rural renewable energy utilizations. The experimental performance results give a good agreement with those ones obtained from the digital computer simulation. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by a variable speed prime mover employing the static VAR compensator (SVC) circuit composed of the thyristor phase controlled reactor (TCR) and the thyristor switched capacitor(TSC) is designed and considered herein for the wind-turbine driven the power conditioner. To validate the effectiveness of the SVC-based voltage regulator of the terminal voltage of the three-phase SEIG, an inductive load parameter disturbances in stand-alone are applied and characterized in this paper. In the stand-alone power utilization system, the terminal voltage response and thyristor triggering angle response of the TCR are plotted graphically. The simulation and the experimental results prove the effectiveness and validity of the proposed SVC which is controlled by the Pl controller in terms of fast response and high performances of the three-phase SEIG driven directly by the rural renewable energy utilization like a variable-speed prime mover.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.19-22
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• 2001

For stabilization and improving power factor in the power lines, various Static Var Compensators(SVC) have been considered to be installed and partly applicated already. With all these merits of the SVC, it stil has demerits, principally evoking harmonic problems. So far, many harmonic reduction type inverters have been used in various parts. In this paper, the reactive power is controlled by amplitude of the output voltage. This paper propose that the multiple voltage source inverter have controllable power factor made by load vary at receive-stage as lagging and leakage control. The theoretical analysis on this system was confirmed through the computer simulation and the experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.101-108
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• 2004

AC electric railroad system receives its power from 3-phase transmission system, Since, trainloads are changing continuously, the voltages for the single-phase load fluctuate in the train garage, and moreover, the fluctuating voltages generate high-order harmonics. This means that there is the difficulty in maintaining power quality in the power system. Therefore, a Static Var Compensator(SVC), which in general compensates the reactive power, is used in order to balance the trainload. In this paper, PSCAD/EMTDC is used for the analysis of harmonic generation in the train garage using SVC. The Total Harmonic Distortion(THD) of voltages is calculated using PSCAD/EMTDC dynamic simulation. As a result, the train garage using SVC improves power quality.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.262-264
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• 1996

This paper presents a new dual loop control using novel vector phase locked loop(VP-PLL) for a high power static var compensator(SVC) with three-level GTO voltage source inverter(VSI). Through circuit DQ-transformation, a simple dq-axis equivalent circuit is obtained. From this, DC analysis is carried out to obtain maximum controllable phase angle ${\alpha}_{max}$ per unit current between the three phase source and the switching function of inverter, and AC open-loop transfer function is given. Because ${\alpha}_{max}$ becomes small in high power SVC, this paper proposes VP-PLL for more accurate $\alpha$-control. As a result, the overall control loop has dual loop structure, which consists of inner VP-PLL for synchronizing the phase angle with source and outer Q-loop for compensating reactive power of load. Finally, the validity of the proposed control method is verified through the experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.8
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• pp.48-53
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• 2006

An electric arc furnace being used in the steel industry is a time-varying non-linear load causing voltage fluctuations to the power system. Flicker can be defined as the effect produced on the human visual perception by a changing emission of light lamps subjected to magnitude fluctuations of their supply voltage. The level of flicker depends on the amplitude, frequency and duration of the voltage fluctuations. In this paper, the voltage fluctuation problem in an 154[kV] system due to the electric arc furnace loads is investigated and the analysis results of the static var compensator application for the voltage flicker mitigation are presented and evaluated by the IEC 61000-3-7.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.51-52
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• 2014

전력계통은 전력수요의 지속적인 성장에 따라서 전력설비의 추가를 지속적으로 추진하고 있지만, 심해지는 환경문제 등으로 인해 용지 확보에 어려움이 있다. 이로 인해 송전선로 장거리화, 용량부족량 등 전력계통에 여러 가지 복잡한 문제가 야기되는데, 이것은 곧 전력계통의 안정도와 직결된다. 이러한 문제를 효과적이면서 경제적인 해결방법으로 FACT(Flexible AC Transmission System)기술이 주목 받고 있다. FACTS 기기 중 SVC(Static Var Compensator)는 상용운전 중이며, 기존 동기조상기에 비해 저렴하고, 신속 정확한 전압제어를 하는 장점이 있다. SVC는 TCR(Thyristor Controlled Reactor)과 TSC(Thyristor Switched Capacitor), FC(Fixed Capacitor)등 여러 종류의 구성을 가질 수 있다. TCR과 TSC는 실제 운전에 앞서 여러 가지 방법으로 검증이 필요하다. 합성 시험회로 설비(Synthetic Test Circuit)는 TCR과 TSC 안에 존재하는 Thyristor Valve의 동작을 실제 동작 조건으로 동작시켜, 동작의 신뢰성을 검증하는 설비이다. 본 논문에서는 TCR의 Operational Test를 위한 STC를 기술하고 있다. 설계된 STC는 PSCAD를 사용하여 검증하였다.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1206-1208
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• 2000

The Static var compensators(SVC) are intensively studied to realize high performance power equipment for electric power systems. Rapid and continuous reactive compensation by the SVC contributes to voltage stabilization, power oscillation damping, overvoltage suppression, minimization of transmission losses and so on. In this paper, instantaneous power vector theory which can expresses the instantaneous apparent power vector is proposed to control reactive power. The validity of the proposed method is confirmed by simulation studies.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.991-1001
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• 2013

Instead of building new substations or transmission lines, proper installation of flexible AC transmission systems (FACTS) devices can make the transmission networks accommodate more power transfers with less expansion cost. In this paper, the problem to maximize power system loadability by optimally installing two types of FACTS devices, namely static var compensator (SVC) and thyristor controlled series compensator (TCSC), is formulated as a mixed discrete-continuous nonlinear optimization problem (MDCP). To reduce the complexity of the problem, the locations suitable for SVC and TCSC installations are first investigated with tangent vector technique and real power flow performance index (PI) sensitivity factor and, with the specified locations for SVC and TCSC installations, a set of schemes is formed. For each scheme with the specific locations for SVC and TCSC installations, the MDCP is reduced to a continuous nonlinear optimization problem and the computing efficiency can be largely improved. Finally, to cope with the technical and economic concerns simultaneously, the scheme with the biggest utilization index value is recommended. The IEEE-14 bus system and a practical power system are used to validate the proposed method.