• Progress in Superconductivity and Cryogenics
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• v.13 no.3
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• pp.19-23
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• 2011

An HTS DC power cable is expected to perfectly eliminate transmission loss caused by resistance. However, when the HTS DC power cable is applied to the power system, loss of the HTS DC power cable is generated due to harmonics caused by HVDC converter. We designed and analyzed the HTS DC power cable with a critical current of 1 kA to investigate the loss characteristics using a finite element method package. In this paper, the loss characteristics caused by harmonics in the HTS DC power cable were analyzed according to order and magnitude of harmonics. Based on the analysis results, the critical current of HTS DC power cable considered with the rated current could be determined to minimize the capacity of cooling system for the design the HTS DC power cable.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.822-823
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• 2011

The authors analyzed harmonic current based loss of a high temperature superconducting (HTS) DC model cable. The loss in HTS DC cable is generated due to the variation of magnetic field caused by harmonic current in a HVDC transmission system. The authors designed and fabricated two meters of HTS DC model cable for verification of real loss characteristic. In this paper, the loss characteristics caused by harmonic current in the HTS DC model cable are analyzed using commercial finite element method software package. The loss of the HTS DC cable is much less than the loss of the HTS AC cable but the loss should be considered to decide a proper capacity of cooling system.

• Progress in Superconductivity and Cryogenics
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• v.12 no.4
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• pp.24-30
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• 2010

The renewable energy source is considered as a good measure to cope with the global warming problem and the fossil energy exhaustion. The construction of electric power plant such as an offshore wind farm is rapidly increasing and this trend is expected to be continued during this century. The bulky and long distance power transmission media is essential to support and promote the sustainable expansion of renewable energy source. DC power cable is generally considered as the best solution and the demand for DC electric power has been rapidly increasing. Especially, the high temperature superconducting (HTS) DC cable system begins to make a mark because of its advantages of huge power transmission capacity, low transmission loss and other environmental friendly aspects. Technical contents of DC HTS cable system are very similar to those of AC HTS cable system. However the DC HTS cable can be operated near its critical current if the heat generation is insignificant, while the operating current of AC HTS cable is generally selected at about 50~70% of the critical current because of AC loss. We chose the specifications of the cable core of 'Tres Amigas' project as an example for our study and investigated the heat generation when the DC HTS cable operated near the critical current by some electric and thermal analyses. In this paper, we listed some technical issues on the design of the DC HTS cable core and described the process of the cable core design. And the results of examination on the current capacity, heat generation, harmonic loss and current distribution properties of the DC HTS cable are introduced.

• Progress in Superconductivity and Cryogenics
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• v.13 no.3
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• pp.5-9
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• 2011

DC high-temperature superconducting(HTS) cable system has attracted a great deal of interest from the view point of low loss, dense structure and large capacity. A HTS cable system is made of cable and termination. The insulating materials and insulation technology must be solved for the long life, reliability and compact of cable system. In this paper, we will report on the dielectric breakdown characteristics of insulating materials for HTS cable and termination. The AC, DC and lightning impulse breakdown strength of laminated polypropylene paper(PPLP) and glass fiber reinforced plastic(GFRP) have been measured under nitrogen pressures in the range of 0.l-0.4MPa. PPLP and GFRP are found to have a significantly higher DC breakdown strength. Also, DC surface flashover voltage of negative polarity is slightly higher than that of positive polarity in GFRP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.545-549
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• 2013

To realize the high-Tc superconducting (HTS) DC cable system, it is important to study not only high current capacity and low loss of conductor but also optimum electrical insulation at cryogenic temperature. A model HTS DC cable system consists of a HTS conductor, semi-conductor, cooling system and insulating materials. Polypropylene laminated paper (PPLP) has been widely adopted as insulating material for HTS machines. However, the fundamental insulation characteristics of PPLP for the development of HTS DC cable have not been revealed satisfactorily until now. In this paper, we will discuss mainly on the breakdown characteristics of 3 sheets PPLP in liquid nitrogen ($LN_2$). The characteristics of the diameter, location of butt-gap, distance between butt-gap length, pressure effect, polarity effect under DC and impulse voltage were studied. Also, the DC polarity reversal breakdown voltage of mini-model cable was measured in $LN_2$ under 0.4 MPa.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.52-56
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• 2007

A high temperature superconducting (HTS) DC cable is ideal for transmitting large blocks of electrical power over a long distance. However, it must be designed to operate reliably within the constraints of the electrical systems. Therefore, a study of the electrical insulation is important to develop a HTS DC cable because it is operated in a cryogenic high voltage environment. This paper discusses the dielectric constructions of the cable and summarizes the experimental results on the DC and impulse dielectric characteristics of the insulation material. in sheet form and mini-model cable configuration. This shows how to design such insulation to be operated reliably. These studies are essential for the insulation design of a HTS DC cable operated in cryogenic environment.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.55-57
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• 2000

In this paper we present the results of tests for the high-Tc superconducting (HTS) power cable core. A prototype HTS cable cores have been constructed using Bi-2223 based Ag-sheathed HTS tapes. HTS cable cores has been tested at 77K with DC currents. Results shows that the cable cores carrying up to 700A DC and self-field effects are discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.97-103
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• 2015

This paper introduces two on-going projects for DC high temperature superconducting (HTS) cable systems in South Korea. This study proposes the application of DC HTS cable systems to enhance power transfer limits of a grid-connected offshore wind farm. In order to develop the superconducting DC transmission system model based on HTS power cables, the maximum transfer limits from offshore wind farm are estimated and the system marginal price (SMP) calculated through a Two-Step Power Transfer (TSPT) model based on PV analysis and DC-optimal power flow. The proposed TSPT model will be applied to 2022 KEPCO systems with offshore wind farms.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.28-31
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• 2008

22.9kV 50MVA HTS power cable has been developed and tested by Korea Electrotechnology Research Institute and LS Cable Company and it was supported by a grant from Center for Applied Superconductivity Technology of the 21st Century Frontier R&D Program. In this paper, DC Ic of 100m HTS cable which is installed at Kochang testing station was measured and analyzed. A measurement technique of DC Ic used by resistance and inductance removal method is established.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.808-809
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• 2008

22.9kV 50MVA HTS power cable has been developed and tested by Korea Electrotechnology Research Institute and LS Cable Company and it was supported by a grant from Center for Applied Superconductivity Technology of the 21st Century Frontier R&D Program. In this paper, DC Ic of 100m HTS cable which is installed at Kochang testing station was measured and analyzed. A measurement technique of DC Ic used by resistance and inductance removal method is established. The HTS power cable is composed of 2 layers for transmission and 1 layer for shield. For the analysis of AC losses in an HTS power cable, 2-dimensional numerical calculation was carried out to define the magnetic field distribution. We calculated the magnetization losses in the HTS core of that cable from these fields. These calculated results are in accordance with those of experiment.