• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.2
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• pp.215-221
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• 2014

To satisfy the high voltage direct current (HVDC) grid connection demand for wind power generation system, a novel topology and control strategy of HVDC grid connection for open-winding permanent magnet synchronous generator (PMSG) based wind power generation system is proposed, in which two generator-side converter and two isolated DC/DC converters are used to transmit the wind energy captured by open winding PMSG to HVDC grid. By deducing the mathematic model of open winding PMSG, the vector control technique, position sensorless operation, and space vector modulation strategy is applied to implement the stable generation operation of PMSG. Finally, the simulation model based on MATLAB is built to validate the availability of the proposed control strategy.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.47-55
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• 2015

This paper proposes the installation of a new modular multilevel converter based high-voltage direct current (MMC-HVDC) system to connect between mainland and Jeju island power systems in Korea in 2020. The purpose is to combine with two old line-commutated converters (LCC)-based HVDC system to achieve a stability of the Jeju island power system. The operation of the overall system will be analyzed in three cases: (i) wind speed is variable, (ii) either one of the LCC-HVDC systems is shutdown because of a fault or overhaul, (iii) a short circuit fault occurs at the mainland side. The effectiveness of the proposed control method is confirmed by the simulation results based on a PSCAD/EMTDC simulation program.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.525-526
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• 2006

One of the electrode in Haenam converter, which is role of rectifier in Jeju-Haenam HVDC system is destroyed and we found many cracks at another electrode and we also found many cracks in Jeju converter station, which is role of inverter of Jeju-Haenam. HVDC system, there is no exact reason for these phenomenon, even though the life cycle of these electrode is 40 years. So, the experts for HVDC system in KEPCO and Anotec corporation, which is manufacturer of electrode, would perform research for the reason of electrode disorder. In this paper analyze the reason of electrode disorder and corrosion in high voltage direct current system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.5
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• pp.750-756
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• 2017

This paper presents a method for DC voltage control of HVDC system connection of offshore wind farms. In the event of fault in AC grid, HVDC system need to meet LVRT regulations. When HVDC system meet LVRT regulation, unbalance is caused between power input and power output for DC link. Therefore, LVRT regulation lead to DC voltage increase of HVDC system. To control the DC voltage increase, the chopper resistor can be suggested. In this paper, DC voltage suppression is proposed using chopper resistor and de-loading. The effectiveness of the chopper resistor was verified using PSCAD/EMTDC.

• Journal of Sensor Science and Technology
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• v.32 no.3
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• pp.199-206
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• 2023

This study presents a novel monitoring technique for underwater high-voltage direct current (HVDC) cables based on the Distributed Acoustic Sensor (DAS). The proposed technique utilizes vibration and acoustic signals generated on HVDC cables to monitor their condition and detect events such as earthquakes, shipments, tidal currents, and construction activities. To implement the monitoring system, a DAS based on phase-sensitive optical time-domain reflectometry (Φ-OTDR) system was designed, fabricated, and validated for performance. For the HVDC cable monitoring experiments, a testbed was constructed on land, mimicking the cable burial method and protective equipment used underwater. Defined various scenarios that could cause cable damage and conducted experiments accordingly. The developed DAS system achieved a maximum measurement distance of 50 km, a distance measurement interval of 2 m, and a measurement repetition rate of 1 kHz. Extensive experiments conducted on HVDC cables and protective facilities demonstrated the practical potential of the DAS system for monitoring underwater and underground areas.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.99-100
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• 2014

전압형 HVDC(High Voltage Direct Current)는 현재 차세대 전력망으로써 각광을 받고 있고 그에 대한 연구가 활발하게 진행 중이다. 많은 논문에서 모듈형 멀티레벨 컨버터(Modular Multilevel Converter, MMC)의 제어 및 보호 방안에 대하여 기술하지만 운영적인 시퀀스 측면에 있어서는 아직 많은 연구가 진행되지 않고 있다. 이에 본 논문은 전압형 HVDC의 AC Yard, DC Yard 및 상위 제어기에 관한 구동 시퀀스에 대하여 기술하고자 한다.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2315-2326
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• 2016

This paper discusses the elimination of DC voltage deviation and the enhancement of load current sharing accuracy in multi-terminal high voltage direct current (MT-HVDC) systems. In order to minimize the power line losses in different parallel network topologies and to insure the stable operation of systems, a decentralized control method based on a modified droop control is presented in this paper. Averaging the DC output voltage and averaging the output current of two neighboring converters are employed to reduce the congestion of the communication network in a control system, and the decentralized control method is implemented. By minimizing the power loss of the cable, the optimal load current sharing proportion is derived in order to achieve rational current sharing among different converters. The validity of the proposed method using a low bandwidth communication (LBC) network for different topologies is verified. The influence of the parameters of the power cable on the control system stability is analyzed in detail. Finally, transient response simulations and experiments are performed to demonstrate the feasibility of the proposed control strategy for a MT-HVDC system.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1499-1507
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• 2015

High voltage direct current transmission based on modular multilevel converter (MMC-HVDC) is one of the most promising power transmission technologies. In this study, the mathematical characteristics of MMC-HVDC are analyzed in a synchronous rotational reference frame. A hybrid current vector controller based on proportional integer plus resonant is used to uniformly control the DC and double-base frequency AC currents under unbalanced grid voltage conditions. A corresponding voltage dependent current order limiter is then designed to solve the overcurrent problems that may occur. Moreover, the circulating current sequence components are thoroughly examined and controlled using a developed circulating current suppressor. Simulation results verify the correctness and effectiveness of the proposed control schemes.

• JOURNAL OF ELECTRICAL WORLD
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• s.447
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• pp.74-79
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• 2014

제주도는 육지와는 물론 여타의 섬 문화와도 극명한 차별성을 지니고 있다. 전력계통 구성도 매우 특이하다. 섬이라는 독립적인 계통 특성상 일부는 제주 지역 내에 있는 발전소에서, 일부는 육지에서 공급을 받는다. 이 중 육지에서 전력을 공급받기 위한 방안으로 한전은 '송전기술의 꽃'이라 불리는 HVDC(High Voltage Direct Current, 초고압 직류 송전)를 채택, 이를 운영하고 있다. 여기에 지난해 말에는 HVDC 실증을 위한 제주 HVDC 스마트센터가 준공됨으로써 HVDC 기술의 국산화에 박차를 가하고 있다. 이제 제주도가 그야말로 국내 HVDC의 교두보이자 산실이 된 것이다. HVDC 기술 자립화를 통해 글로벌 시장 공략의 든든한 밑거름을 제공할 제주 HVDC의 현재 및 미래를 소개한다.

• Journal of Sensor Science and Technology
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• v.28 no.3
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• pp.187-190
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• 2019

We proposed and demonstrated DC(direct current) optical current sensor based on Faraday effect for HVDC(high voltage direct current). The RIG((Bi1.3Gd0.43Y1.27)Fe5O12) was adopted as Faraday device because of its high Verdet constant and good thermal stability. The differential amplification scheme for signal processing was present. The sensor showed high linear response for the input current. Measurement range of the sensor was 0~200A and measurement error was less than 1%.