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Yanggu, South Korea

Yoon D.-H.,Korea University | Lee H.,Korea University | Park B.,PQ Technology INC. | Jang G.,Korea University
Fusion Engineering and Design | Year: 2011

The KSTAR system, which includes a large amount of nonlinear load, is a relatively high reactive power consumption load which injects harmonic currents into the power system which could result in the possibility for a power system perturbation to occur in the transmission lines, affecting nearby customers. In order to maintain the power quality and power factor in the inner system of the KSTAR system and the adjacent distribution lines, the assessment of the effect of the DC power supply in the KSTAR system is required for appropriate countermeasures to be put in place. In this paper, on the basis of a preliminary inspection of the power system near a KSTAR system, the simulation of a compensating device is performed for the prevention of abnormal voltage variations caused by a large amount of reactive and nonlinear load. In addition, through the comparison of the pre- and post-application of compensation devices in the actual power system, it is verified that a stable operation of the KSTAR nuclear fusion experimental system can be achieved. © 2011 Elsevier B.V. Source


Park B.,PQ Technology INC. | Lee H.,Korea University | Jang G.,Korea University | Han B.,Myongji University
Electric Power Systems Research | Year: 2010

This paper proposes the most feasible solution to overcome the failure of the 2nd harmonic filter in the static VAR compensator (SVC) which operates with the DC electric arc furnace (EAF) at Gwangyang Steel Mill in Korea. In order to investigate the causes of this failure, various measurements were carried out on the DC EAF and the main transformer at the PCC (point of common connection). It was concluded that the two causes for the failure are; the inrush current in the main transformer, and the parallel resonance between the system impedance and the harmonic filter. Three solutions to suppress the transformer inrush current and another three solutions to avoid the parallel resonance are suggested. The feasibility of these solutions was verified through the computer simulation with PSCAD/EMTDC. The most feasible solution to avoid further failures of the 2nd harmonic filter was selected, based on the estimated result for the six optional solutions in the point of performance and cost. © 2009 Elsevier B.V. All rights reserved. Source


Hong S.-L.,National Fusion Research Institute | Kong J.-D.,National Fusion Research Institute | Kim Y.-S.,National Fusion Research Institute | Eom D.-Y.,National Fusion Research Institute | And 3 more authors.
Fusion Engineering and Design | Year: 2014

The superconducting magnet power supply which supplies superconducting magnet coil (SC) with the power to generate plasma during a KSTAR experiment for nuclear fusion research is a nonlinear load. Characteristic harmonics are generally produced since it converts AC to DC using 6 or 12 pulsed operation. However, non-characteristic harmonics or inter-harmonics are generated according to output control characteristics. Also, 95% out of the power generated from superconducting magnet coil is reactive power. Therefore, harmonic and reactive power occurring during operation have some bad influences such as voltage drop, voltage distortion and decrease in power factor on the KSTAR power system, and reactive power compensator (RPC) & harmonic filter (HF) system which is able to compensate harmonic and reactive power at the same time was established and has been operated [1]. However, out of non-characteristic harmonics and inter-harmonics caused by output control characteristics of superconducting magnet power supply, the more compensation volume of the RPC & HF system increases, the more voltage distortion with harmonic expansion is caused by harmonics in a low-order band due to the parallel resonance in a low-order band between the KSTAR power system and the RPC & HF system. As a result, it has serious effect on the injection capacity restriction of the RPC & HF system, the unstable operation control of superconducting magnet coil, and the operation of main cooling facilities. This paper presents reasons of the resonance phenomenon of the KSTAR power system and suggests a design plan of additional facilities for stable operation of the KSTAR power system, and proves their effects through the simulation and test results. © 2014 Published by Elsevier B.V. Source


Hong S.-L.,National Fusion Research Institute | Kong J.-D.,National Fusion Research Institute | Kim Y.-S.,National Fusion Research Institute | Eom D.-Y.,National Fusion Research Institute | And 2 more authors.
Fusion Engineering and Design | Year: 2012

The Korea Superconducting Tokamak Advanced Research (KSTAR) device requires a large pulse power to generate and confine plasma in order to function as a nuclear fusion device. Such a large pulse power causes voltage-drop and voltage-distortion in the electric power system, because it generates large reactive power and harmonic currents. These effects are detrimental to other experimental devices and deteriorate the power quality delivered by the power system. Therefore, it is important to stabilize the KSTAR power system by compensating for the reactive power and rejecting the harmonic currents using a Reactive Power Compensator (RPC) & Harmonic Filter (HF) system. The TSC type RPC & HF system has been fabricated to have a total capacity of 35 MVar and included two features. The first is a fast response speed of within 10 cycles to compensate for the reactive power. The second is a stable KSTAR power system in which no resonance is detected due to the installation of the TSC type RPC & HF system. This paper presents simulation results of the TSC type RPC & HF system and test results of the plasma experiment of KSTAR carried out in 2009. © 2011 Elsevier B.V. All rights reserved. Source


Kong J.-D.,National Fusion Research Institute | Hong S.-L.,National Fusion Research Institute | Hwang I.-S.,National Fusion Research Institute | Choi J.-H.,National Fusion Research Institute | And 6 more authors.
IEEE Transactions on Plasma Science | Year: 2010

After more than ten years of construction, the Korea Superconducting Tokamak Advanced Research (KSTAR) device finally completed its assembly in June 2007. We conducted the first plasma operation from April 2008 to July 2008 and succeeded in the plasma generation in July 2008. The electric power system for the first plasma operation is made up of various electric devices, including 154-kV circuit-breaker systems, a 154/22.9-kV 50-MVA transformer, 22.9-kV circuit-breaker systems, and reactive power compensator (RPC) and harmonic filter (HF) systems. When the poloidal-field magnet power supplies were operated, the reactive power and harmonic currents (12n ± 1) were generated instantaneously in the KSTAR electric power system for the first plasma generation due to the characteristics of the KSTAR superconducting coils. The measured voltage drop and harmonics seriously affected the other experimental equipment as well. Therefore, it is important to compensate the reactive power and remove the harmonics with the RPC and HF system for the superconducting tokamak device. In this paper, we discuss the stability of the electric power system and the operational results of the RPC and HF systems during the KSTAR first plasma operation. Furthermore, the upgrade plan of the electric power system based on the KSTAR operation plan will be discussed. © 2010 IEEE. Source

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