• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.236-237
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• 2012

본 연구에서는 Thyristor로 구성되는 HVDC System의 Thyristor밸브를 시험하기위한 새로운 합성시험회로를 제안하고 그 성능과 동작을 분석한 내용에 대해 기술하고 있다. 제안하는 시스템의 동작 타당성을 체계적으로 분석하기 위해 PSCAD/EMTDC 소프트웨어를 이용한 시뮬레이션 모델을 개발하였으며 이를 기반으로 하드웨어 시스템을 제작하여 제안하는 시스템의 동작특성을 분석하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 추계학술대회 논문집
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• pp.111-112
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• 2015

MMC HVDC(Multi-level Modular Converter High Voltage Direct Current)는 현재 차세대 전력망으로써 각광을 받고 있고 그에 대한 연구가 활발하게 진행 중이다. 본 논문에서는 모듈형 멀티레벨 컨버터를 이용한 전압형 HVDC 시스템의 AC 전류제어기에 대하여 기술하고자 한다. 일반적으로 사용되는 회전변환을 통한 DQ전류제어와 PR제어를 사용하여 응답특성을 PSCAD/EMTDC를 통하여 비교 검증하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.139-141
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• 2000

High voltage direct current(HVDC) transmission system uses the phase controlled rectifier triggered by means of IPC(individual phase control) or EPC(equidistant pulse control). Most HVDC system has adopted EPC method that can solve the harmonic instability problem of IPC method in weak power system. But EPC has inherent indirect synchronizing problem requiring the closed loop control. This paper presents the new gate pulse generating method for 12-pulse HVDC converter, which combines IPC with EPC. Simulation and test results are presented. The basic concept is that it generates the gating pulse for 12-pulse converter by synthesizing the internal phase reference using the frequency and phase information of a sin91e phase voltage. To ensure the reliability of the external phase input, Potential transformer that detects the phase voltage has redundancy. Using fault detecting algorithm the healthy input is always guaranteed. And the frequency compensation function was reinforced.

• Journal of Power Electronics
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• 제16권6호
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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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• 제19권6호
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• pp.1467-1476
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• 2019

Grid unbalanced faults can cause core saturation of power transformer and produce lower-order harmonics. These issues increase the electrical stress of power electronic devices and can cause a tripping of an entire HVDC system. In this paper, based on the positive-sequence and negative-sequence impedance model of a VSC-HVDC system as seen from the point of common connection (PCC), the resonance problem is analyzed and the factors determining the resonant frequency are obtained. Furthermore, to suppress over-voltage and over-current during resonance, a novel method using a virtual harmonic resistor is proposed. The virtual harmonic resistor emulates the role of a resistor connected in series with the commutating inductor without influencing the active and reactive power control. Simulation results in PSCAD/EMTDC show that the proposed control strategy can suppress resonant over-voltage and over-current. In addition, it can be seen that the proposed strategy improves the safety of the VSC-HVDC system under unbalanced faults.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.318-319
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• 2011

This paper presents a new user defined modeling about HVDC system based on the PSS/E. The principles, methods and procedures of user defined modeling for dynamic simulation are expounded. Comparing beween the dynamic simulations results of a power system by CDC4T in the PSS/E library and a user defined model CDCKU1 respectively, we illustrate the general usage of custom features and verify the model accuracy. Future work about CDCKU series and practical models will be considered to enhance the power system stability in Korea.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.217-218
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• 2015

This paper presents an anaysis of parallel operated HVDC and AC transmissions' transient stability and control analysis by using PACAD/EMTDC program. We measured and analyzed power trasfer in case of various operating conditions including ac, dc faults to find an effects to the power system of the operating conditions. In this project, Simulation of ac/dc parallel system that maximize margins of the ac system and allow a higher power transfer is performed and analyzed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1289-1291
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• 2000

The operation of Back-To-Back HVDC system for asynchronous connection is described. It can exchange electric power up to 300 MW between separately operated two rower systems, making the interaction on each system minimum. The analysis is done under three different AC transmission lines interconnected to BTB HVDC.

• 한국태양에너지학회 논문집
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• 제35권3호
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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.

• 전력전자학회논문지
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• 제19권5호
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• pp.450-456
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• 2014

In HVDC converters that employ a line-commutated control, reactive power is absorbed by the rectifier and inverter terminals during AC/DC conversion. An AC filter usually consists of filters and large shunt capacitors to supply reactive power to the HVDC station. When STATCOM is used to supply reactive power to the HVDC system with AC filter, the low-order harmonics generated from STATCOM can result in a resonance between the shunt capacitor and AC network. Therefore, a control strategy based on selective harmonic elimination is adopted to minimize the low-order harmonics from STATCOM. The cancellation of harmonic instabilities is verified through simulations in PSCAD/EMTDC.