• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.252-254
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• 2006

The recent improvement in the performance of digital processor, the application of control technology, which used in the HVDC(High Voltage Direct Current) system with the digital processors, has increased. Having this research development as the basis, this paper presents an achievement of progression by tuning the parameter of PI controller based on Genetic Algorithms(GAs) and by controlling with PI controller with a developed simulator by applying the Matrix operating function, voltage source switching element, modified nodal analysis which can include transformer and the backward Euler which does not create the problem of numerical oscillation. As a result, I expect this development in the simulator HVDC System to bring more application in the field of control technology research with an expanded practicality.

• Progress in Superconductivity and Cryogenics
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• v.17 no.1
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• pp.32-35
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• 2015

Many kinds of high temperature superconducting (HTS) devices are being developed due to its several advantages. In particular, the advantages of HTS devices are maximized under the DC condition. A line commutated converter (LCC) type high voltage direct current (HVDC) transmission system requires large capacity of DC reactors to protect the converters from faults. However, conventional DC reactor made of copper causes a lot of electrical losses. Thus, it is being attempted to apply the HTS DC reactor to an HVDC transmission system. The authors have developed a 8 mH class HTS DC reactor and a model-sized LCC type HVDC system. The HTS DC reactor was operated to analyze its operational characteristics in connection with the HVDC system. The voltage at both ends of the HTS DC reactor was measured to investigate the stability of the reactor. The voltages and currents at the AC and DC side of the system were measured to confirm the influence of the HTS DC reactor on the system. Two 5 mH copper DC reactors were connected to the HVDC system and investigated to compare the operational characteristics. In this paper, the operational characteristics of the HVDC system with the HTS DC reactor according to firing angle are described. The voltage and current characteristics of the system according to the types of DC reactors and harmonic characteristics are analyzed. Through the results, the applicability of an HTS DC reactor in an HVDC system is confirmed.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.3
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• pp.263-269
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• 2017

This paper proposes a novel circulating current control method for an MMC-HVDC system based on Vector PI control. The method can suppress second-order harmonics of the circulating currents under balanced and unbalanced grid conditions. The proposed method is robust to grid frequency variation. The effectiveness of the proposed method is verified through frequency response and time domain simulation.

• Journal of the Korean Solar Energy Society
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• v.35 no.3
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• pp.49-56
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• 2015

This paper presents a comparative operating characteristics of static var compensator(SVC) and static synchronous compensator(STATCOM) for compensating the reactive power in the Jeju power system. There are two kinds of reactive power compensating systems, which are active and passive system in the applications of the line commutated converter type high voltage direct current (LCC-HVDC). In the Jeju power system, two STATCOMs as active compensating system have been operating. Even though STATCOM has good performance compared with SVC, economical efficiency of former system is not good to the latter system. So, it is necessary to examine the performance and economical efficiency depend on the intention before appling the system. To compare the operating characteristics of two systems in the Jeju power system, simulations have been carried out for case studies that both of the HVDC system have transient state by using PSCAD/EMTDC program.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.459-468
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• 2020

The pole interaction of the line-commutated converter high-voltage direct current (HVDC) is analyzed, and a practical solution that uses a surge arrester is proposed. Jeju HVDC No. 2 is a double-monopole HVDC link that has a rated power capacity of 2 × 200 MW and was commissioned in 2012. During normal operation, Jeju HVDC No. 2 is operated in the bipolar mode to minimize the loss caused by the dedicated metallic return. However, when one pole of the inverter valve is bypassed, a commutation failure can occur in the other pole. This phenomenon is called pole interaction in this work. This pole interaction interrupts the HVDC power transfer for almost 2 s and may affect the stability of the power system. This research proposes the installation of a surge arrester at the inverter neutral, which can be an effective and practical solution for pole interaction. The HVDC system is analyzed, and the residual voltage of the surge arrester is determined. Detailed simulation using PSCAD/EMTDC demonstrates that the proposed method eliminates the pole interaction of the bipolar-operated HVDC.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.85-86
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• 2011

In this paper, the virtual power grid of Jeju in 2020 is modelled including not only VSC HVDC(Voltage Source Current-High Voltage Direct Current) but also wind power generators as 200MW for onshore and 500MW for offshore by PSCAD/EMTDC. Each active power and reactive power are able to controlled by the VSC HVDC. In addition, to verify the characteristic of the modeling VSC HVDC, those wind power generators are cut off from the grid. The result show that the modeling power grid of Jeju become stabilized after 0.1second from failure.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.7-8
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• 2016

본 논문에서는 모듈형 멀티레벨 컨버터 (Modular Multilevel Converter ; MMC) 고압 직류 송전 (High Voltage Direct Current ; HVDC) 시스템의 순환전류 성분을 제어하기 위해 VPI (Vector Proportional Integral) 제어기를 적용한 순환전류 제어 기법을 제안하였다. 제안한 방식은 기존의 준공진 (Quasi-Resonant) 제어기를 적용한 방식과 비교하여 계통 주파수 변동에 강인하고 넓은 공진 대역폭 선정이 용이한 장점을 갖는다. 제안한 순환전류 제어기의 성능은 기존의 준공진 제어기를 적용한 기법과 계통 전압 단상지락 및 계통 주파수 변동 상황에서 시뮬레이션을 통하여 비교 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.4
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• pp.270-277
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• 2008

Capacitor Commutated Converter HVDC system is required the small reactive power. It has the advantage of an application to the week grid because the firing angle ${\alpha}$ can be increased to a value well beyond $180^{\circ}$. In this paper, The three HVDC converter arrangements which are the CCC(Capacitor Commutated Converter) and the CSCC(Controlled Series Capacitor Convertor) and Conventional Converter are compared the dynamic character. and it find that the CCC HVDC is operating with more reliability. The simulation was conducted to the PSCAD/EMTDC.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.69-70
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• 2015

100년전 토마스 에디슨이 주장한 직류 전력 전송 방식인 DC 송전은 AC 송전보다 장거리 송전 시 손실이 적고 안정도가 좋다. 또한 다른 주파수를 가진 두 지역을 연계하여 전력을 전송 할 수있으며 전력 조류를 제어할 수 있다는 장점을 가지고 있다. 그러나, AC와 DC전력간의 변환 장치를 필요로 하여 설비 구축 비용이 비싸다는 점과 고도의 제어기술 및 검증 기술이 요구된다는 단점은 이제 굳이 논할 필요도 없는 사실이다. 이에 수년전부터 국내에서도 손실이 적고 안정도가 좋다는 장점이 지속적으로 부각되고 있으며 친 환경 발전 및 스마트 그리드의 호황 속에 DC 송전 기술의 필요성은 차세대 기술로 각광받으며 DC 고압 직류 방식인 HVDC (High Voltage Direct Current, 이하 HVDC)에 대한 연구 및 사업이 시작되었다. 그러나, HVDC 시스템의 손실 측정은 계산으로 인해 이루어지고 있으며, 이에 대한 실측 방안은 현재 없다. 또한 시스템 설계 시, 고려해야 하는 시스템의 Feasibility 및 신뢰성에서 손실은 중요한 지표 중의 하나이다. 그러나, HVDC 를 개발하고 설치, 운전하여 양도 또는 인수하는 과정에서 손실은 전력 요금과 직결되기 때문에 계산 및 측정에 대한 논란이 있는 실정이다. 계산 및 측정하는 HVDC의 손실은 무부하 손실 및 부하 손실로 구분된다. 본 논문에서는 현재 사용되고 있는 손실 계산 방법을 소개하고 당사에서 측정을 실시한 HVDC 손실 측정 방법에 대해서 소개하고자 한다.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.443-451
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• 2015

The stability of a multi-terminal direct current (MTDC) system is often influenced by its control strategy. To improve the stability of the MTDC system, the control strategy of the MTDC system must be appropriately adopted. This paper deals with estimating stability of a MTDC system based on the line-commutated converter based high voltage direct current (LCC HVDC) system with an inverter with constant extinction angle (CEA) control or a rectifier with constant ignition angle (CIA) control. In order to evaluate effects of two control strategies on stability, a MTDC system is tested on two conditions: initialization and changing DC power transfer. In order to compare the stability effects of the MTDC system according to each control strategy, a mathematical MTDC model is analyzed in frequency domain and time domain. In addition, Bode stability criterion and transient response are carried out to estimate its stability.