- Email: [email protected]
Recent progress of HTS cable project
Physica C 468 (2008) 2014–2017
Contents lists available at ScienceDirect
Physica C journal homepage: www.elsevier.com/locate/physc
Recent progress of HTS cable project T. Masuda *, H. Yumura, M. Watanabe Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024, Japan
a r t i c l e
i n f o
Article history: Available online 10 June 2008 PACS: 84.71.Fk Keywords: High temperature superconducting cable
a b s t r a c t A lot of developments of HTS wires and their applications have been conducted since the discovery of HTS materials in the world. It has been recently reported that critical current of BSCCO wires improved to more than 200 A at 77 K and a large amount of wire was provided with high quality as industrial products. This improvement can be expected to accelerate the commercialization of HTS applications such as an HTS cable, HTS motor and so on. As the proofs of such trends, Sumitomo Electric constructed two HTS cable systems and started their operations in the USA and Korea last year. One of them is the HTS cable in Albany, NY, which has a capacity of 34.5 kV and 800 A and 350 m in length. It has been operated in a real grid without any trouble for 9 months. The other is the HTS cable in Korea, which has a capacity of 22.9 kV and 1250 A and 100 m in length. Its operation also started in the KEPCO testing yard last year. These results demonstrate reliance and stability of its operation. Recently, a new national project of an HTS cable has just started in Japan to demonstrate the operation in a real grid and study the system operations including a monitoring method, an alarm system, a maintenance method, etc. This paper reports the results of Albany and Korea projects and an outline of the new project. Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction Since 1988 when BSCCO HTS material was discovered in Japan, Sumitomo Electric Industries, Ltd. has been developing BSCCO wires to get real an applicable HTS wire. The recently developed CT-OPTM (controlled over pressure) process developed by Sumitomo Electric (SEI) got the BSCCO wire to be higher performance of superconductivity and increased its productivity for practical use [1]. It is believed that this innovation made the HTS applications to move forward to commercialization because of providing an amount of BSCCO wires for their developments.
ure. Moreover, there is no leakage of the magnetic field at the outside of the cable by its superconducting shield. Therefore HTS cable doesn’t effect any electro-magnetic influence to their outside. Reliability is one of the most important factors for the power cables which work for a long time as a component of the infrastructure. The primary factor of degradation in conventional cables is considered to repeated expansion and contraction of the cable itself due to temperature changing caused by load fluctuation and/or ambient temperature changing throughout the day and the year. On the other hand, HTS cables are operated at the almost constant temperature in liquid nitrogen so that they are not expected to have any damage due to thermo-mechanical motion.
1.1. Merits of HTS cable 1.2. 3-In-one HTS cable Features and advantages of HTS cables are classified into three general categories: economical, environmental and life-time reliability. HTS cables achieve large power transmission capacity and low power loss with a compact size. This is effective in reducing the costs of cable system construction and operation. As environmental features, the first feature is reducing energy consumption because of lower transmission loss. In addition, because HTS cables are cooled with liquid nitrogen that is used as an insulating material, the HTS cables are non-flammable and non-explosive in nat* Corresponding author. Tel.: +81 6 6466 5630; fax: +81 6 6466 8239. E-mail address: [email protected] (T. Masuda). 0921-4534/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.physc.2008.05.259
Sumitomo has been developing HTS cable with 3-in-One type [2], which means that three cable cores in one cryostat as shown in Fig. 1. A superconducting conductor is wound with BSCCO wires on the former, spirally. As electrical insulation, PPLP is wound on the conductor. For canceling the magnetic field caused by conductor current, BSCCO wires are also wound on the electrical insulation to form a superconducting shield. For protection against a short circuit current, the Cu shield is composed of copper tapes. To reduce the tension caused by thermal contraction from room temperature to liquid nitrogen temperature, the three cores are stranded with some slack in three cores. The cable cryostat is composed of a double stainless steel corrugated pipe and an anticorrosion layer. The
T. Masuda et al. / Physica C 468 (2008) 2014–2017
2015
1800 A [4]. The heat invasion into the cable system in no-load condition was measured. The heat loss in the 350-m HTS cable section (including the joint section) is 1.0 kW, which was almost same as the designed value. A DC withstand voltage test was conducted at DC 100 kV for 5 min successfully in conformity to the AEIC standard [4]. 2.2. In-grid operation
Fig. 1. Structure of a 3-in-one HTS cable.
space between inner and outer pipes is vacuumed to reduce the heat invasion from the outside. Some tension members are attached on the cryostat in case of installation with a large tension, if necessary. 2. Albany project An HTS cable demonstration project has been conducted on an actual power grid of National Grid Company in Albany NY. This project was funded by the Department of Energy [3]. The rated voltage, current and capacity of this power line was 34.5 kV, 800 A, and 48 MVA, respectively. The cable was installed in 350 m underground conduit with an inner diameter of 6 in. The world’s first cable-to-cable joint was placed inside a vault, and both ends of the cable were connected to overhead power transmission lines as shown in Fig. 2. 2.1. Commissioning test After cooling with liquid nitrogen completely, some measurements and tests were conducted as the commissioning test. The critical current (Ic) measurements were conducted for each phase conductor at an average cable temperature of 73 K. The critical currents of all phases were 2300 A, respectively, when the current was defined as 1 lV/cm, for all three phases. The measured Ics matched the values expected from the results of a sample test at 77 K of
Fig. 2. HTS cable and termination in Albany.
From the results of tests and measurements above mentioned, it was concluded that the cable system had good performance for ingrid operation. The cable was connected to the actual grid by National Grid on July, 2006. The operating status of the HTS cable system is monitored for 24 h a day by the Remote Operation Center (ROC) in the BOC Group. The operating status can also be monitored in real time from anywhere around the world via the internet. In addition, the temperature, pressure and other operating conditions of cooling system can be fine-adjusted by remote operation. This system enables unattended operation at the Albany site. Fig. 3 shows the transmitted electricity and cable inlet and outlet temperatures during the operation [5]. Transmitted electricity has been very variable but the temperatures have been very stable, which means that system was working stably and controlled very well. During the operation, the cable experienced a fault current of 7 kA in 8 cycles in November, 2006. At that time, the breaker was operated normally and the operation was suspended. After deliberate checking the cable, no damage on the cable or the system was found and then the operation was restarted. The transmission was stopped in May, 2007 followed by around 7000 h successful operation [5]. After the long term operation, the insulation resistance and Ic measurement test were conducted to check the soundness of the HTS cable cores. The insulation test showed that the cable maintain good electrical insulation properties. The Ic measurement was conducted for each phase conductor at an average cable temperature of 73 K. The Ics were 2.3 kA (defined by 1 lV/cm) for each of all three phases, which were the same values as ones at commissioning test. Then, the cable system was warmed up to room temperature to replace the 30-m section. 2.3. YBCO cable verification (phase-2) In Phase-2, the BSCCO 30-m section was planned to be removed and replaced to the YBCO HTS cable which uses YBCO wires manufactured by SuperPower [6]. The structures of the YBCO cable are described in Table 1. The YBCO cable design is almost same as the BSCCO one except the number of superconducting layers. The number of superconducting layers in the conductor and the shield are three and two for the YBCO cable compared to two and one for the BSCCO cable. After the design suitability was verified, a 30 m YBCO cable was manufactured completely [7]. The total amount of wire was 9.7 km, and the Ic of the YBCO wires used in the product cable was about average 70 A at 4 mm width and 77 K. SEI carried out the shipping tests in Table 2 and demonstrated enough good performance to ship the cable to Albany. The measured Ic values of the conductor and shield were greater than 2600 A and 2400 A, respectively. These Ic values nearly matched the estimated Ic values from the YBCO wires. The YBCO cable was installed in the 30 m section shown in Fig. 4, successfully. Assembling the joint between YBCO cable and BSCCO cable in the vault and assembling the termination were also completed. The operation in the grid is expected to restart soon.
2016
T. Masuda et al. / Physica C 468 (2008) 2014–2017
20 Cable Outlet Temperature
Temperature [K]
70
16
Cable Inlet Temperature
69
12
68
8
67
4
Transmitted Electricity [MVA]
71
Transmitted Electricity
66
0
7/20
8/17
9/14
10/12
11/9
12/7
1/4
2/1
3/1
3/29
4/26
Date (2006-2007) Fig. 3. Transmitted electricity and cable inlet and outlet temperatures for 7000 h operation.
3. KEPCO project Table 1 Components of YBCO cable core Items
Contents
Former HTS conductor Electric Insulation HTS Shield Protection layer Cable diameter
Stranded Cu wires YBCO wire, three layers PPLP + LN2, thickness 4.5 mm YBCO wire, two layer Copper tape 135 mm
Table 2 Shipping test results of YBCO cable Items
Contents
Results
Critical current (at 77 K) AC loss measurement Voltage tests
Conductor <2600 A Shield <2400 A 0.34 W/m/ph at 800 A
Good
AC 69 kV for 10 min, Imp ± 200, 10 shots/each Bending at 2.4m = 18D
No break down
Bending test
Half of BSCCO cable
No Ic degradation
Fig. 4. Installation of YBCO cable at Albany site.
As a case study on the practical application of superconducting technology, the Korea Electric Power Corporation (KEPCO) planned to research on an operation method of superconducting cables. For such purpose, a 100 m HTS cable with 22.9 kV class, which is the power distribution level in Korea; and 1250 A, which is five times the standard capacity of 250 A; was installed at the KEPCO test site and has been evaluated by themselves. Fig. 5 shows the cable installed in the tunnel at the test site. At the commissioning test in 2006, critical current of the cable conductor was measured and it was 2350 A at 72 K. A 33 kV singlephase voltage was also applied to the cable for five minutes, successfully. Following these tests, the acceptance test was conducted with the rated ground voltage of 13.2 kV and a nominal current of 1250 A for 48 h, successfully [8]. After handing over the system to KEPCO, KEPCO has been conducting various tests and operation from the view point of an end user. The cable has already had a test with nominal current and voltage for 40 days, several heat cycles and load cycle tests at the condition of 1.25 kA for 8 h and 0 kA for 16 h with 20 kV for 30 days. As the results, any abnormal response was not observed so far [9].
Fig. 5. KEPCO HTS cable in tunnel at the test site.
2017
T. Masuda et al. / Physica C 468 (2008) 2014–2017
4. New HTS cable project in Japan
Fy 2007
A new HTS cable project supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO) has just started in Japan. Target of this project is to operate a 66 kV, 200 MVA HTS cable in the real grid in order to demonstrate its reliability and stable operation. Tokyo Electric Power Company (TEPCO) provides the real grid and studies the impact of connecting the HTS cable to the existing conventional facilities. SEI will manufacture the HTS cable, terminations and a joint. Mayekawa Mfg. Co., Ltd will provide a cooling system. A steering committee which consists of the university professors, researchers in the electric utilities, the national institutes and so on, is held to provide various opinions, advices and comments for this project. 4.1. Goal of HTS cable The HTS cable in this project is 66 kV class and the 3-in one HTS cable. A 66 kV line is the most popular transmission line in Tokyo Electric grid. One of the applications is to install the 66 kV HTS cable in the duct from a 275 kV transmission line circulating around Tokyo area to the center of the metropolitan instead of a 275 kV conventional cable in the tunnel. When the capacity of the cable is 350 MVA, the construction cost of the HTS cable system is expected to be more economical than the conventional cable [10]. Therefore, the target current is set as 3 kA. For decreasing the AC loss, a new type DI-BSCCO wire [11] will be used for the HTS cable. This new wire has thinner thickness and narrower width than a normal type BSCCO wire and its filaments are twisted. The wire is now under development and it is expected that its AC loss is less than one forth of normal BSCCO wire. The final target of AC loss of the cable is less than 1 W/m/ph at 3 kA. A demonstration site will be decided soon with the consideration of cable electric parameters and installation space. The cable length is expected to be between 200 and 300 m depending on a site configuration. 4.2. Operation system Other system components, such as a monitoring system, an alarm system and a switching system will be also built and customized to the operation of the HTS cable. The team will study the failure mode of the HTS cable, network protection and alarm method. The team will also study the influences of the fault current
66kV 154kV
66kV
Switch Bypass cable PT CT
Switch 154kV/66kV Transformer
Power Control Center
Data Transmission
Monitoring System
Joint Superconducting Cable LN2 Line
Pump
LN2 Buffer
Refrigerator
Data Transmission
Cooling Control Center
Remote Control
Fig. 6. Schematic view of the demonstration system.
Component Developments
Fy 2008 Pre-system manufac. & test
Fy 2009
Fy2010
HTS cable system manufact. & installation
Fy2011 Operation & evaluation
Fig. 7. Schedule of the HTS cable project.
and serge voltage to the HTS cable and considers the operation process. The schematic view of the demonstration system in case of placing at the substation is shown in Fig. 6. 4.3. Project schedule The total project period is 5 years. The project schedule is shown in Fig. 7. In the fiscal 2007, components of HTS cable system will be studied and confirmed. In the fiscal 2008 and early 2009, the pre-system will be constructed in the factory to demonstrate basic performance of the HTS cable and its accessories. Then the actual HTS cable is manufactured in 2009 and constructed and operated at the site in 2010 and 2011. Its operation period in the real grid is scheduled for one year. 5. Conclusion Sumitomo joined recently two HTS cable project in Korea and the USA. Both cables have been installed and operated successfully. Especially, the Albany cable was connected to the real grid and operated for about 7000 h, successfully. In phase 2, a 30 m YBCO cable was manufactured and installed at the site. The operation will re-start soon. At the same time, a new HTS cable national project has just started in Japan. This HTS cable with 66 kV class will be also demonstrated in the real grid. Other HTS cables are now demonstrating and constructing over the world and its reliability and stability is being clarified. There is no doubt that the age of HTS cable commercialization is coming at the next door. References [1] T. Kato, S. Kobayashi, K. Yamazaki, K. Ohkura, M. Ueyama, N. Ayai, J. Fujikami, E. Ueno, M. Kikuchi, K. Hayashi, K. Sato, Physica C 412–414 (2004) 1066. [2] T. Masuda, T. Kato, M. Hirose, K. Sato, Electron. Eng. Jpn. 162 (2008) 827. [3] T. Masuda, H. Yumura, M. Watanabe, H. Takigawa, Y. Ashibe, C. Suzawa, T. Kato, Y. Yamada, K. Sato, S. Isojima, C. Weber, A. Dada, J.R. Spadafore, IEEE Trans. Appl. Supercond. 15 (2005) 1806. [4] T. Masuda, H. Yumura, M. Watanabe, H. Takigawa, Y. Ashibe, C. Suzawa, H. Ito, M. Horose, K. Sato, S. Isojima, C. Weber, R. Lee, J. Moscovic, presented at ASC 2006, 1LB02. [5] H. Yumura, T. Masuda, M. Watanabe, H. Takigawa, Y. Ashibe, H. Ito, M. Hirose, K. Sato, presented at CEC/ICMC 2007, C2-S-01. [6] A. Rar, J. Reeves, V. Selvamanickam, presented at CEC/ICMC 2007, M1-P-01. [7] M. Ohya, H. Yumura, Y. Ashibe, H. Ito, T. Masuda, K. Sato, presented at CEC/ ICMC 2007, C2-S-02. [8] M. Watanabe, T. Masuda, H. Yumura, H. Takigawa, Y. Ashibe, H. Ito, C. Suzawa, M. Hirose, K. Yatsuka, K. Sato, S. Isojima, presented at ISS 2006, SAP-1. [9] S.H. Sohn, J.H. Lim, H.S. Yang, D.L. Kim, H.S. Ryoo, C.D. Kim, D.H. Kim, S.K. Lee, S.D. Hwang, presented at CEC/ICMC 2007, C2-S-04. [10] M. Hirose, Y. Yamada, T. Masuda, K. Sato, R. Hata, SEI Tech. Rev. 62 (2006) 15. [11] N. Ayai, S. Kobayashi, M. Kikuchi, T. Ishida, J. Fujikami, K. Yamazaki, S. Yamade, K. Hayashi, K. Sato, H. Kitaguchi, H. Kumakura, K. Osamura, J. Shimoyama, H.Kamiyo, Y. Fukumoto, presented at ISS 2007, WT-2-INV.
Contents lists available at ScienceDirect
Physica C journal homepage: www.elsevier.com/locate/physc
Recent progress of HTS cable project T. Masuda *, H. Yumura, M. Watanabe Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024, Japan
a r t i c l e
i n f o
Article history: Available online 10 June 2008 PACS: 84.71.Fk Keywords: High temperature superconducting cable
a b s t r a c t A lot of developments of HTS wires and their applications have been conducted since the discovery of HTS materials in the world. It has been recently reported that critical current of BSCCO wires improved to more than 200 A at 77 K and a large amount of wire was provided with high quality as industrial products. This improvement can be expected to accelerate the commercialization of HTS applications such as an HTS cable, HTS motor and so on. As the proofs of such trends, Sumitomo Electric constructed two HTS cable systems and started their operations in the USA and Korea last year. One of them is the HTS cable in Albany, NY, which has a capacity of 34.5 kV and 800 A and 350 m in length. It has been operated in a real grid without any trouble for 9 months. The other is the HTS cable in Korea, which has a capacity of 22.9 kV and 1250 A and 100 m in length. Its operation also started in the KEPCO testing yard last year. These results demonstrate reliance and stability of its operation. Recently, a new national project of an HTS cable has just started in Japan to demonstrate the operation in a real grid and study the system operations including a monitoring method, an alarm system, a maintenance method, etc. This paper reports the results of Albany and Korea projects and an outline of the new project. Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction Since 1988 when BSCCO HTS material was discovered in Japan, Sumitomo Electric Industries, Ltd. has been developing BSCCO wires to get real an applicable HTS wire. The recently developed CT-OPTM (controlled over pressure) process developed by Sumitomo Electric (SEI) got the BSCCO wire to be higher performance of superconductivity and increased its productivity for practical use [1]. It is believed that this innovation made the HTS applications to move forward to commercialization because of providing an amount of BSCCO wires for their developments.
ure. Moreover, there is no leakage of the magnetic field at the outside of the cable by its superconducting shield. Therefore HTS cable doesn’t effect any electro-magnetic influence to their outside. Reliability is one of the most important factors for the power cables which work for a long time as a component of the infrastructure. The primary factor of degradation in conventional cables is considered to repeated expansion and contraction of the cable itself due to temperature changing caused by load fluctuation and/or ambient temperature changing throughout the day and the year. On the other hand, HTS cables are operated at the almost constant temperature in liquid nitrogen so that they are not expected to have any damage due to thermo-mechanical motion.
1.1. Merits of HTS cable 1.2. 3-In-one HTS cable Features and advantages of HTS cables are classified into three general categories: economical, environmental and life-time reliability. HTS cables achieve large power transmission capacity and low power loss with a compact size. This is effective in reducing the costs of cable system construction and operation. As environmental features, the first feature is reducing energy consumption because of lower transmission loss. In addition, because HTS cables are cooled with liquid nitrogen that is used as an insulating material, the HTS cables are non-flammable and non-explosive in nat* Corresponding author. Tel.: +81 6 6466 5630; fax: +81 6 6466 8239. E-mail address: [email protected] (T. Masuda). 0921-4534/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.physc.2008.05.259
Sumitomo has been developing HTS cable with 3-in-One type [2], which means that three cable cores in one cryostat as shown in Fig. 1. A superconducting conductor is wound with BSCCO wires on the former, spirally. As electrical insulation, PPLP is wound on the conductor. For canceling the magnetic field caused by conductor current, BSCCO wires are also wound on the electrical insulation to form a superconducting shield. For protection against a short circuit current, the Cu shield is composed of copper tapes. To reduce the tension caused by thermal contraction from room temperature to liquid nitrogen temperature, the three cores are stranded with some slack in three cores. The cable cryostat is composed of a double stainless steel corrugated pipe and an anticorrosion layer. The
T. Masuda et al. / Physica C 468 (2008) 2014–2017
2015
1800 A [4]. The heat invasion into the cable system in no-load condition was measured. The heat loss in the 350-m HTS cable section (including the joint section) is 1.0 kW, which was almost same as the designed value. A DC withstand voltage test was conducted at DC 100 kV for 5 min successfully in conformity to the AEIC standard [4]. 2.2. In-grid operation
Fig. 1. Structure of a 3-in-one HTS cable.
space between inner and outer pipes is vacuumed to reduce the heat invasion from the outside. Some tension members are attached on the cryostat in case of installation with a large tension, if necessary. 2. Albany project An HTS cable demonstration project has been conducted on an actual power grid of National Grid Company in Albany NY. This project was funded by the Department of Energy [3]. The rated voltage, current and capacity of this power line was 34.5 kV, 800 A, and 48 MVA, respectively. The cable was installed in 350 m underground conduit with an inner diameter of 6 in. The world’s first cable-to-cable joint was placed inside a vault, and both ends of the cable were connected to overhead power transmission lines as shown in Fig. 2. 2.1. Commissioning test After cooling with liquid nitrogen completely, some measurements and tests were conducted as the commissioning test. The critical current (Ic) measurements were conducted for each phase conductor at an average cable temperature of 73 K. The critical currents of all phases were 2300 A, respectively, when the current was defined as 1 lV/cm, for all three phases. The measured Ics matched the values expected from the results of a sample test at 77 K of
Fig. 2. HTS cable and termination in Albany.
From the results of tests and measurements above mentioned, it was concluded that the cable system had good performance for ingrid operation. The cable was connected to the actual grid by National Grid on July, 2006. The operating status of the HTS cable system is monitored for 24 h a day by the Remote Operation Center (ROC) in the BOC Group. The operating status can also be monitored in real time from anywhere around the world via the internet. In addition, the temperature, pressure and other operating conditions of cooling system can be fine-adjusted by remote operation. This system enables unattended operation at the Albany site. Fig. 3 shows the transmitted electricity and cable inlet and outlet temperatures during the operation [5]. Transmitted electricity has been very variable but the temperatures have been very stable, which means that system was working stably and controlled very well. During the operation, the cable experienced a fault current of 7 kA in 8 cycles in November, 2006. At that time, the breaker was operated normally and the operation was suspended. After deliberate checking the cable, no damage on the cable or the system was found and then the operation was restarted. The transmission was stopped in May, 2007 followed by around 7000 h successful operation [5]. After the long term operation, the insulation resistance and Ic measurement test were conducted to check the soundness of the HTS cable cores. The insulation test showed that the cable maintain good electrical insulation properties. The Ic measurement was conducted for each phase conductor at an average cable temperature of 73 K. The Ics were 2.3 kA (defined by 1 lV/cm) for each of all three phases, which were the same values as ones at commissioning test. Then, the cable system was warmed up to room temperature to replace the 30-m section. 2.3. YBCO cable verification (phase-2) In Phase-2, the BSCCO 30-m section was planned to be removed and replaced to the YBCO HTS cable which uses YBCO wires manufactured by SuperPower [6]. The structures of the YBCO cable are described in Table 1. The YBCO cable design is almost same as the BSCCO one except the number of superconducting layers. The number of superconducting layers in the conductor and the shield are three and two for the YBCO cable compared to two and one for the BSCCO cable. After the design suitability was verified, a 30 m YBCO cable was manufactured completely [7]. The total amount of wire was 9.7 km, and the Ic of the YBCO wires used in the product cable was about average 70 A at 4 mm width and 77 K. SEI carried out the shipping tests in Table 2 and demonstrated enough good performance to ship the cable to Albany. The measured Ic values of the conductor and shield were greater than 2600 A and 2400 A, respectively. These Ic values nearly matched the estimated Ic values from the YBCO wires. The YBCO cable was installed in the 30 m section shown in Fig. 4, successfully. Assembling the joint between YBCO cable and BSCCO cable in the vault and assembling the termination were also completed. The operation in the grid is expected to restart soon.
2016
T. Masuda et al. / Physica C 468 (2008) 2014–2017
20 Cable Outlet Temperature
Temperature [K]
70
16
Cable Inlet Temperature
69
12
68
8
67
4
Transmitted Electricity [MVA]
71
Transmitted Electricity
66
0
7/20
8/17
9/14
10/12
11/9
12/7
1/4
2/1
3/1
3/29
4/26
Date (2006-2007) Fig. 3. Transmitted electricity and cable inlet and outlet temperatures for 7000 h operation.
3. KEPCO project Table 1 Components of YBCO cable core Items
Contents
Former HTS conductor Electric Insulation HTS Shield Protection layer Cable diameter
Stranded Cu wires YBCO wire, three layers PPLP + LN2, thickness 4.5 mm YBCO wire, two layer Copper tape 135 mm
Table 2 Shipping test results of YBCO cable Items
Contents
Results
Critical current (at 77 K) AC loss measurement Voltage tests
Conductor <2600 A Shield <2400 A 0.34 W/m/ph at 800 A
Good
AC 69 kV for 10 min, Imp ± 200, 10 shots/each Bending at 2.4m = 18D
No break down
Bending test
Half of BSCCO cable
No Ic degradation
Fig. 4. Installation of YBCO cable at Albany site.
As a case study on the practical application of superconducting technology, the Korea Electric Power Corporation (KEPCO) planned to research on an operation method of superconducting cables. For such purpose, a 100 m HTS cable with 22.9 kV class, which is the power distribution level in Korea; and 1250 A, which is five times the standard capacity of 250 A; was installed at the KEPCO test site and has been evaluated by themselves. Fig. 5 shows the cable installed in the tunnel at the test site. At the commissioning test in 2006, critical current of the cable conductor was measured and it was 2350 A at 72 K. A 33 kV singlephase voltage was also applied to the cable for five minutes, successfully. Following these tests, the acceptance test was conducted with the rated ground voltage of 13.2 kV and a nominal current of 1250 A for 48 h, successfully [8]. After handing over the system to KEPCO, KEPCO has been conducting various tests and operation from the view point of an end user. The cable has already had a test with nominal current and voltage for 40 days, several heat cycles and load cycle tests at the condition of 1.25 kA for 8 h and 0 kA for 16 h with 20 kV for 30 days. As the results, any abnormal response was not observed so far [9].
Fig. 5. KEPCO HTS cable in tunnel at the test site.
2017
T. Masuda et al. / Physica C 468 (2008) 2014–2017
4. New HTS cable project in Japan
Fy 2007
A new HTS cable project supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO) has just started in Japan. Target of this project is to operate a 66 kV, 200 MVA HTS cable in the real grid in order to demonstrate its reliability and stable operation. Tokyo Electric Power Company (TEPCO) provides the real grid and studies the impact of connecting the HTS cable to the existing conventional facilities. SEI will manufacture the HTS cable, terminations and a joint. Mayekawa Mfg. Co., Ltd will provide a cooling system. A steering committee which consists of the university professors, researchers in the electric utilities, the national institutes and so on, is held to provide various opinions, advices and comments for this project. 4.1. Goal of HTS cable The HTS cable in this project is 66 kV class and the 3-in one HTS cable. A 66 kV line is the most popular transmission line in Tokyo Electric grid. One of the applications is to install the 66 kV HTS cable in the duct from a 275 kV transmission line circulating around Tokyo area to the center of the metropolitan instead of a 275 kV conventional cable in the tunnel. When the capacity of the cable is 350 MVA, the construction cost of the HTS cable system is expected to be more economical than the conventional cable [10]. Therefore, the target current is set as 3 kA. For decreasing the AC loss, a new type DI-BSCCO wire [11] will be used for the HTS cable. This new wire has thinner thickness and narrower width than a normal type BSCCO wire and its filaments are twisted. The wire is now under development and it is expected that its AC loss is less than one forth of normal BSCCO wire. The final target of AC loss of the cable is less than 1 W/m/ph at 3 kA. A demonstration site will be decided soon with the consideration of cable electric parameters and installation space. The cable length is expected to be between 200 and 300 m depending on a site configuration. 4.2. Operation system Other system components, such as a monitoring system, an alarm system and a switching system will be also built and customized to the operation of the HTS cable. The team will study the failure mode of the HTS cable, network protection and alarm method. The team will also study the influences of the fault current
66kV 154kV
66kV
Switch Bypass cable PT CT
Switch 154kV/66kV Transformer
Power Control Center
Data Transmission
Monitoring System
Joint Superconducting Cable LN2 Line
Pump
LN2 Buffer
Refrigerator
Data Transmission
Cooling Control Center
Remote Control
Fig. 6. Schematic view of the demonstration system.
Component Developments
Fy 2008 Pre-system manufac. & test
Fy 2009
Fy2010
HTS cable system manufact. & installation
Fy2011 Operation & evaluation
Fig. 7. Schedule of the HTS cable project.
and serge voltage to the HTS cable and considers the operation process. The schematic view of the demonstration system in case of placing at the substation is shown in Fig. 6. 4.3. Project schedule The total project period is 5 years. The project schedule is shown in Fig. 7. In the fiscal 2007, components of HTS cable system will be studied and confirmed. In the fiscal 2008 and early 2009, the pre-system will be constructed in the factory to demonstrate basic performance of the HTS cable and its accessories. Then the actual HTS cable is manufactured in 2009 and constructed and operated at the site in 2010 and 2011. Its operation period in the real grid is scheduled for one year. 5. Conclusion Sumitomo joined recently two HTS cable project in Korea and the USA. Both cables have been installed and operated successfully. Especially, the Albany cable was connected to the real grid and operated for about 7000 h, successfully. In phase 2, a 30 m YBCO cable was manufactured and installed at the site. The operation will re-start soon. At the same time, a new HTS cable national project has just started in Japan. This HTS cable with 66 kV class will be also demonstrated in the real grid. Other HTS cables are now demonstrating and constructing over the world and its reliability and stability is being clarified. There is no doubt that the age of HTS cable commercialization is coming at the next door. References [1] T. Kato, S. Kobayashi, K. Yamazaki, K. Ohkura, M. Ueyama, N. Ayai, J. Fujikami, E. Ueno, M. Kikuchi, K. Hayashi, K. Sato, Physica C 412–414 (2004) 1066. [2] T. Masuda, T. Kato, M. Hirose, K. Sato, Electron. Eng. Jpn. 162 (2008) 827. [3] T. Masuda, H. Yumura, M. Watanabe, H. Takigawa, Y. Ashibe, C. Suzawa, T. Kato, Y. Yamada, K. Sato, S. Isojima, C. Weber, A. Dada, J.R. Spadafore, IEEE Trans. Appl. Supercond. 15 (2005) 1806. [4] T. Masuda, H. Yumura, M. Watanabe, H. Takigawa, Y. Ashibe, C. Suzawa, H. Ito, M. Horose, K. Sato, S. Isojima, C. Weber, R. Lee, J. Moscovic, presented at ASC 2006, 1LB02. [5] H. Yumura, T. Masuda, M. Watanabe, H. Takigawa, Y. Ashibe, H. Ito, M. Hirose, K. Sato, presented at CEC/ICMC 2007, C2-S-01. [6] A. Rar, J. Reeves, V. Selvamanickam, presented at CEC/ICMC 2007, M1-P-01. [7] M. Ohya, H. Yumura, Y. Ashibe, H. Ito, T. Masuda, K. Sato, presented at CEC/ ICMC 2007, C2-S-02. [8] M. Watanabe, T. Masuda, H. Yumura, H. Takigawa, Y. Ashibe, H. Ito, C. Suzawa, M. Hirose, K. Yatsuka, K. Sato, S. Isojima, presented at ISS 2006, SAP-1. [9] S.H. Sohn, J.H. Lim, H.S. Yang, D.L. Kim, H.S. Ryoo, C.D. Kim, D.H. Kim, S.K. Lee, S.D. Hwang, presented at CEC/ICMC 2007, C2-S-04. [10] M. Hirose, Y. Yamada, T. Masuda, K. Sato, R. Hata, SEI Tech. Rev. 62 (2006) 15. [11] N. Ayai, S. Kobayashi, M. Kikuchi, T. Ishida, J. Fujikami, K. Yamazaki, S. Yamade, K. Hayashi, K. Sato, H. Kitaguchi, H. Kumakura, K. Osamura, J. Shimoyama, H.Kamiyo, Y. Fukumoto, presented at ISS 2007, WT-2-INV.