• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.6
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• pp.494-502
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• 2014

This paper presents a control method of the modular multilevel converter - high-voltage direct current (MMC-HVDC) system to regulate grid voltage on the basis of the Jeju Island power system. In this case, the MMC-HVDC system is controlled as a static synchronous compensator (Statcom) to exchange the reactive power with the power grid. The operation of the MMC-HVDC system is verified by using the PSCAD/EMTDC simulation program. The Jeju Island power system is first established on the basis of the parameters and measured data from the real Jeju Island power system. This power system consists of two line-commutated converter - high-voltage direct current (LCC-HVDC) systems, two Statcom systems, wind farms, thermal power plants, transformers, and transmission and distribution lines. The proposed control method is then applied by replacing one LCC-HVDC system with a MMC-HVDC system. Simulation results with and without using the MMC-HVDC system are compared to evaluate the effectiveness of the control method.

• 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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• 2012.07a
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• pp.301-302
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• 2012

국내에서 HVDC (High Voltage DC transmission System) 관련 기술은 한국전력공사 및 전력연구원 중심으로 제주와 해남간 설치된 HVDC시스템의 설치 및 운영 기술에 많이 국한되어 왔었다. 그러나 기술을 바탕으로 2010년부터 민간기업인 LS산전과 한국전력공사의 공동 개발을 통하여 60MW ${\pm}80kV$급 전류형 HVDC시스템 설계 및 제작을 추진하여 시스템 설계, 기기 설계 사양, 제작사양서 등의 설계 핵심 기술을 상당부분 확보하는 계기가 되었다. 현재 설계된 Pilot HVDC 시스템은 제작 완료되었고, 제주 실증단지에 설치 및 시험 중에 있으며 2012년 내에 실증운전을 통해서 최종적으로 시스템 설계 기술을 검증할 계획이다. 이 같은 연구를 통하여 상당부분 HVDC 시스템에 대한 독자적인 설계 능력을 갖추게 될 것이다.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2001-2006
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• 2017

This paper explains the effects of the weak signal of a rotating-type electric field mill sensor fabricated for measuring the intensity of the electric field generated by high-voltage direct current (HVDC) power transmission lines. The fabricated field mill consists of two isolated electrode vanes, a motor driver, and a ground part. The sensor plate is exposed to and shielded from the electric field by means of a rotary shutter consisting of a motor-driven mechanically complementary rotor/stator pair. When the uncharged sensor plate is exposed to an electric field, it becomes charged. The rotating electrode consists of several conductive vanes and is connected to the ground part, so that it is shielded. Determining the appropriate design variables such as the speed of the vane, its shape, and the distance between the two electrodes, is essential for ensuring optimal performance. By varying the speed, the weak signal characteristics which is used to signal processing and calibration experiment are quite different. Each weak signal pattern was analyzed along with the output voltage characteristics, in order to be able to determine the intensity of the electric field generated by HVDC power transmission lines with accuracy.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.646-651
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• 1996

This paper presents the study results of four transmission methods to enchance transmission capability. The four transmission methods studied were FACTS, HVDC, High Phase Order and new conductor material method. The study was Performed based on mid and long term KEPCO system in 2000 and 2006 year. Among them FACTS(Flexible AC Transmission System) is an exciting new field which holds great promise for improved utilization of AC transmission systems.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.141-147
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• 2019

Recently, the biggest issue in the electricity industry is the increase in renewable energy, and various technologies are being developed to ensure the capacity of the power system. In addition, super-grids linking power systems are being pushed to utilize eco-friendly energy between countries and regions worldwide. The HVDC transmission technology is required to link the power network between regions with different characteristics of the power system such as frequency and voltage. Until now, Korea has applied HVDC transmission technology that connects mainland and Jeju Island with submarine cables. But, the HVDC transmission technology is still developing for long-distance high-capacity power transmission from power parks on the east coast to load-tight areas near the metropolitan area. Considering the high population density and mountainous domestic environment, it is pushing for commercialization of the design technology of the ${\pm}500kV$ Double Bipole with metallic return wire transmission line to transmit large-scale power of 8 GW using minimal right of ways. In this paper, the insulation characteristics were studied for the design of double-bipole transmission tower with metallic return wire, which is the first time in the world. And the air insulation characteristics resistant to the various overvoltage phenomena occurring on transmission lines were verified through a full-scale impulse voltage test.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1221-1225
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• 2010

The application of the AC and DC lines on the same transmission tower is an economical and practical approaching that increase the power transmission capacity of an existing transmission corridor. But, In this case, Inductive and capacitive coupling between AC and DC lines on the same tower should be investigated in advance. According to the installation plan of 80kV ${\pm}$60MW bipole HVDC in Cheju, KOREA that will be commissioned until 2011, DC lines will parallely operate with 154kV 2 AC lines in existed 154kV AC 4 lines transmission tower. This paper presents the steady state analysis results about the interaction between 154kV AC and 80kV DC lines in the same transmission tower.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.14-19
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• 2011

The implemetation of the AC and DC lines on the same transmission tower is an economical and practical approaching that increase the power transmission capacity of an existing transmission corridor. But, In this case, Inductive and capacitive coupling between AC and DC lines on the same tower should be investigated in advance. According to the installation plan of ${\pm}80kV$ 60MW bipole HVDC in Jeju island, KOREA that will be commissioned until 2011, DC lines will parallely operate with 154kV 2 AC lines in existed 154kV AC 4 lines transmission tower. This paper presents the transient analysis results about the interaction between 154kV AC and 80kV DC lines in the same transmission tower.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.758-763
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• 2014

These days, the advantages of DC power system are consistently stand out in korea that was a small power loss and high stability. Needs of DC power transmission technology is focused In the midst of a smart grid and environment friendly generation technology boom that is needed for next generation technology. Researches and businesses for HVDC(High Voltage Direct Current) system has been began. But, Needs of HVDC equipment and system commissioning technology are not on the rise until now. In particular, South Korea's HVDC technology is after the foot runner of advanced country and company. In addition, There is no experience for equipment verification and commissioning technology. And Experts of HVDC are rare. Who has been fully understood hardware and system as a whole, and identified all the equipment's characteristic. Recently, Academia and industry are recognized a needs of HVDC technology. But it does not received a recognition of technical value. In this paper, introduce issues when we apply the IEEE's verification method for HVDC system, especially DC current measurement system, DC CT(Direct Current Transformer), among the HVDC equipments. And Proposes remedial methods on the issue in order to recognize the necessity that was HVDC equipments's verification and commissioning technology research should be focused on.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1791-1795
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• 2007

Small ions generated at conductor corona sources remain in the atmosphere until they recombine with ions of opposite polarity, attach to aerosols, or make contact with an object. Ion current density is major factor to design conductor configuration of DC overhead transmission line. Several techniques have been used to measure the ion current of HVDC overhead transmission line. In this study, the ion current density was measured by a plate electrode made of a metal flat board at DC corona cage. The sensitivity of the plate electrode is $0.156uA/m^2/V$. To obtain an useful database on corona discharge, it is necessary to do corona test on several kinds of conductor bundles. Therefore, a number of experiments were conducted on several kinds of conductor bundles. To reliably analyze ion effects, corona cage test data were obtained over a long period of time under various weather conditions and expressed as a statistical distribution. Ion current density distribution in foul weather shows a significant increase in levels over the corresponding fair weather. Based on this results, we evaluated the environmental characteristic caused by ion flow of three candidated conductor bundles.