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Development of REBCO HTS Magnet of Magnetic Bearing for Large Capacity Flywheel Energy Storage System
Available online at www.sciencedirect.com
ScienceDirect Physics Procedia 65 (2015) 253 – 256
27th International Symposium on Superconductivity, ISS 2014
Development of REBCO HTS Magnet of Magnetic Bearing for Large Capacity Flywheel Energy Storage System. Shinichi Mukoyama*1, Taro Matsuoka1, Makoto Furukawa1, Kengo Nakao1, Ken Nagashima2, Masafumi Ogata2, Tomohisa Yamashita2, Hitoshi Hasegawa2, Kazuhiro Yoshizawa2, Yuuki Arai2, Kazuki Miyazaki2, Shinichi Horiuchi3, Tadakazu Maeda4, Hideki Shimizu5* 1Furukawa Electric Co, Ltd., 2Railway Technical Research Institute, 3Yamanashi Prefectural Government, 4KUBOTEK Corporation, 5MIRAPRO Co., Ltd.
Abstract A flywheel energy storage system (FESS) is a promising electrical storage system that moderates fluctuation of electrical power from renewable energy sources. The FESS can charge and discharge the surplus electrical power repetitively with the rotating energy. Particularly, the FESS that utilizes a high temperature superconducting magnetic bearing (HTS bearing) is lower loss than conventional FESS that has mechanical bearing, and has property of longer life operation than secondary batteries. The HTS bearing consists of a HTS bulk and double-pancake coils used 2nd generation REBCO wires. In the development, the HTS double-pancake coils were fabricated and were provided for a levitation test to verify the possibility of the HTS bearing. We successfully confirmed the magnetic field was achieved to design value, and levitation force in the configuration of one YBCO bulk and five double pancake coils was obtained to a satisfactory force of 39.2 kN (4 tons). © 2015 The Authors. Published by Elsevier Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the ISS 2014 Program Committee. Peer-review under responsibility of the ISS 2014 Program Committee Keywords: High-Tc superconductivity, Flywheel, Energy storage, REBCO, Magnet, Bearing
1. Introduction The dependence rate on renewable power source such as a solar power generator and a wind power generator should be increased for a global warming measure. However, the increasing of the renewable energy brings many problems in power networks and grid, such as voltage rising, surplus electricity, and lack of adjustment capacity of the frequency. The New Energy and Industrial Technology Development Organization (NEDO) started a new project of ‘Development of next generation flywheel energy storage system’ that could adjust short-period frequency irregularities and storage large amounts of surplus electricity from the future-introduced renewable power generators. A flywheel energy storage
* tel. +81-436-42-1716 fax.+ 81-436-42-1687 E-mail address: [email protected]
1875-3892 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the ISS 2014 Program Committee doi:10.1016/j.phpro.2015.05.139
254
Shinichi Mukoyama et al. / Physics Procedia 65 (2015) 253 – 256
system (FESS) charges electrical power from the kinetic energy of a rotating flywheel, and discharges the power by transforming the kinetic energy into electrical power via an electrical motor and generator. The features of the FESS are instant output, non-aging deterioration, and long-life operation. Furukawa and Railway Technical Research Institute (RTRI) are developing a high temperature superconducting magnetic bearing (HTS bearing) of a rotating axle in the NEDO project of the next generation flywheel energy storage system. The HTS bearing of the FESS is expected to be much more efficient in term of low friction loss, long-life operation, and maintenance-free compared to a mechanical bearing. 2. DESIGN CONCEPT OF 300kW, 100kWh FLYWHEEL ENERGY STORAGE SYSTEM The structure of the FESS we develop is shown in Fig.1. The final target in our project is 1MW of output and 300 kWh of storage energy. To realize the storage energy and output power, the flywheel weight of about 10 tons and the rotational speed of 6,000 rpm are needed. A carbon fiber reinforced plastic (CFRP) has been applied to a flywheel rotor in order to withstand the centrifugal force of rotation. Moreover, the flywheel rotor is stored in a high vacuum vessel to reduce energy loss from air friction. The HTS bearing consists of a HTS bulk and a HTS magnet, and supports the tonclass weight flywheel by diamagnetic effect (Maissunar effect) of the bulk in the magnetic field generated by the HTS magnet. We decided to carry out the demonstration and verification test in 2015 by connecting a prototype of the FESS to a solar power station in the real power network. The prototype model is one third capacity model of the final target, and the capacity is 300 kW and 100 kWh shown in Table 1.
㻹㼛㼠㼛㼞㻛㻌㻳㼑㼚㼑㼞㼍㼠㼛㼞 㼂㼍㼏㼡㼡㼙㻌㼂㼑㼟㼟㼑㼘 㻯㻲㻾㻼㻌㼞㼛㼠㼛㼞
㻴㼀㻿㻌㼎㼑㼍㼞㼕㼚㼓
Fig. 1 HTS flywheel energy storage system. Table 1. SPECIFICATION OF PROTOTYPE AND TARGET OF THE FESS Item
Prototype
Power Capacity Bearing
300 kW 100 kWh Rotor: HTS bulk Stator: HTS magnet 4,000 kg 6,000 rpm
Rotor weight Rotor speed
3. DESIGN OF HTS BEARING The levitation force of a cylindrical HTS bulk in magnetic field depends on the shape of the bulk, strength of the magnetic field, and magnetic gradient [1]. The force for the FESS was solved from a magnetic analysis by a generalpurpose simulation program of ANSYS. Five double pancake coils were stacked to levitate the 4,000 kg weight of the 100 kWh prototype model as Fig.2. The analyzed result of the relationship between the levitation force and the maximum field in the coils are shown inFig.3. The levitation force of 39.2 kN (4 tons) is realized by the current load of 74.0 A that generated the maximum magnetic field of 3.4 T
Shinichi Mukoyama et al. / Physics Procedia 65 (2015) 253 – 256
Fig. 2 Layout of five HTS double-pancake coils and a HTS bulk of the HTS bearing of the 100 kWh FESS.
Fig. 3 Analysis result of relationship between levitation force and the maximum magnetic field in the five DP coils.
4. Levitation test of HTS bearing for the prototype model 4-1 Current loading test One HTS coil was fabricated using the HTS REBCO wires with 6 mm in width, which were manufactured by SuperPower Inc.. The HTS coil was the double-pancake coil had an inner diameter of 120 mm and an outer diameter of 260 mm. SuperPower doped pinning centers into the REBCO wires to achieve good high field performance, such as high critical current in a high field. The coil fabrication used the technology of the ‘YOROI coil’ (Y-based Oxide superconductor and Reinforcing Outer Integrated coil) developed by Chubu Electric Power Company [2]. The specifications of the DP coil are indicated in table 2. TABLE 2 SPECIFICATION OF THE HTS DOUBLE-PANCAKE COIL Item
Specification
Wire
Product of Superpower
Width of tape
6 mm
Thickness of tape
0.1 mm
Ic (77K s.f.)
̚100 A
Inner diameter
120 mm
Outer diameter
260 mm
Height of the coil
17.6 mm
The DP coil was installed in the vacuum vessel and was cooled by a first-stage GM refrigerator that had cooling power of 180W at first-stage. A current loading test was conducted by keeping the coil temperature at 54 K. Fig. 4 shows the results of the current loading test. The critical current of the coil had over 110 A, and we confirmed that the DP coils had the satisfied current loading performance at operation temperature of 50 K. 4-2 Levitation test We set up the levitation test configuration that consisted of the five DP-coils and the HTS bulk made by Nippon Steel & Sumitomo Metal Corporation. The HTS coils were stored in the vacuum vessel of low pressure helium gas circumstance. The DP coils were conductively cooled by the GM refrigerator at 50 K and the HTS bulk was cooled by using low pressure helium gas as cooling medium at 53 K. The levitation forces were measured by a load cell on the top of the equipment, and the results are shown in Fig. 5. The levitation force achieved 40 kN, which is the satisfaction force against the targeted force of 39.2 kN for the prototype FESS.
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256
Shinichi Mukoyama et al. / Physics Procedia 65 (2015) 253 – 256
Coil voltage [μV]
80 70 60
50 40 30 20 10 0 -10 0
20
40
60
80
100
120
140
Coil current [A] Fig. 4 Current and voltage characteristics of one double pancake coil at 54K
Levitation Force(kN)
50
40 30
20 10 0 0
10
20
30 40 50 60 Coil Current [A]
70
80
90
Fig. 5 Result of levitation test of HTS bulk and 5 double pancake coils.
5. Conclusion We verified possibility of the magnetic bearing using REBCO HTS coils through the current loading test and the levitation test by five DP coils and the HTS bulk. After the stand alone test of the bearing, we will embed the HTS bearing into the 100 kWh-flywheel system. Moreover, in order to examine an inhibitive effect against fluctuation in the renewable power source, our team will perform an in-grid test as the FESS will be connected to the mega-solar facility that located in Mt. Komekura in Yamanashi. Acknowledgements This development was a part of ‘Development of next generation flywheel energy storage system’ that included in ‘Development of safe and low cost large scale energy storage system project’ supported by NEDO. Authors appreciate the support from Mr. Nagaya of Chubu Electric Power Co., Inc., and members of Hagoromo Electric Co., Ltd. on coil development and fabrication. References [1] [2]
K. Nagashima, H. Seino, Y. Miyazaki, Y. Arai, N. Sakai, M. Murakami, Force density of magnetic bearing using superconducting coils and bulk superconductorsࠊQuarterly Report of RTRI, Vol. 49 No. 2, 2008, pp 127-132. S. Nagaya, T. Watanabe, T. Tamada, M. Naruse, N. Kashima, T. Katagiri, N. Hirano, S. Awaji, H. Oguro and A. Ishiyama, Develop ment of High Strength Pancake Coil with Stress Controlling Structure by REBCO Coated Conductor, Applied Superconductivity, IEEE Transactions on Vol. 23, Iss. 3, 4601204, 2013
ScienceDirect Physics Procedia 65 (2015) 253 – 256
27th International Symposium on Superconductivity, ISS 2014
Development of REBCO HTS Magnet of Magnetic Bearing for Large Capacity Flywheel Energy Storage System. Shinichi Mukoyama*1, Taro Matsuoka1, Makoto Furukawa1, Kengo Nakao1, Ken Nagashima2, Masafumi Ogata2, Tomohisa Yamashita2, Hitoshi Hasegawa2, Kazuhiro Yoshizawa2, Yuuki Arai2, Kazuki Miyazaki2, Shinichi Horiuchi3, Tadakazu Maeda4, Hideki Shimizu5* 1Furukawa Electric Co, Ltd., 2Railway Technical Research Institute, 3Yamanashi Prefectural Government, 4KUBOTEK Corporation, 5MIRAPRO Co., Ltd.
Abstract A flywheel energy storage system (FESS) is a promising electrical storage system that moderates fluctuation of electrical power from renewable energy sources. The FESS can charge and discharge the surplus electrical power repetitively with the rotating energy. Particularly, the FESS that utilizes a high temperature superconducting magnetic bearing (HTS bearing) is lower loss than conventional FESS that has mechanical bearing, and has property of longer life operation than secondary batteries. The HTS bearing consists of a HTS bulk and double-pancake coils used 2nd generation REBCO wires. In the development, the HTS double-pancake coils were fabricated and were provided for a levitation test to verify the possibility of the HTS bearing. We successfully confirmed the magnetic field was achieved to design value, and levitation force in the configuration of one YBCO bulk and five double pancake coils was obtained to a satisfactory force of 39.2 kN (4 tons). © 2015 The Authors. Published by Elsevier Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the ISS 2014 Program Committee. Peer-review under responsibility of the ISS 2014 Program Committee Keywords: High-Tc superconductivity, Flywheel, Energy storage, REBCO, Magnet, Bearing
1. Introduction The dependence rate on renewable power source such as a solar power generator and a wind power generator should be increased for a global warming measure. However, the increasing of the renewable energy brings many problems in power networks and grid, such as voltage rising, surplus electricity, and lack of adjustment capacity of the frequency. The New Energy and Industrial Technology Development Organization (NEDO) started a new project of ‘Development of next generation flywheel energy storage system’ that could adjust short-period frequency irregularities and storage large amounts of surplus electricity from the future-introduced renewable power generators. A flywheel energy storage
* tel. +81-436-42-1716 fax.+ 81-436-42-1687 E-mail address: [email protected]
1875-3892 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the ISS 2014 Program Committee doi:10.1016/j.phpro.2015.05.139
254
Shinichi Mukoyama et al. / Physics Procedia 65 (2015) 253 – 256
system (FESS) charges electrical power from the kinetic energy of a rotating flywheel, and discharges the power by transforming the kinetic energy into electrical power via an electrical motor and generator. The features of the FESS are instant output, non-aging deterioration, and long-life operation. Furukawa and Railway Technical Research Institute (RTRI) are developing a high temperature superconducting magnetic bearing (HTS bearing) of a rotating axle in the NEDO project of the next generation flywheel energy storage system. The HTS bearing of the FESS is expected to be much more efficient in term of low friction loss, long-life operation, and maintenance-free compared to a mechanical bearing. 2. DESIGN CONCEPT OF 300kW, 100kWh FLYWHEEL ENERGY STORAGE SYSTEM The structure of the FESS we develop is shown in Fig.1. The final target in our project is 1MW of output and 300 kWh of storage energy. To realize the storage energy and output power, the flywheel weight of about 10 tons and the rotational speed of 6,000 rpm are needed. A carbon fiber reinforced plastic (CFRP) has been applied to a flywheel rotor in order to withstand the centrifugal force of rotation. Moreover, the flywheel rotor is stored in a high vacuum vessel to reduce energy loss from air friction. The HTS bearing consists of a HTS bulk and a HTS magnet, and supports the tonclass weight flywheel by diamagnetic effect (Maissunar effect) of the bulk in the magnetic field generated by the HTS magnet. We decided to carry out the demonstration and verification test in 2015 by connecting a prototype of the FESS to a solar power station in the real power network. The prototype model is one third capacity model of the final target, and the capacity is 300 kW and 100 kWh shown in Table 1.
㻹㼛㼠㼛㼞㻛㻌㻳㼑㼚㼑㼞㼍㼠㼛㼞 㼂㼍㼏㼡㼡㼙㻌㼂㼑㼟㼟㼑㼘 㻯㻲㻾㻼㻌㼞㼛㼠㼛㼞
㻴㼀㻿㻌㼎㼑㼍㼞㼕㼚㼓
Fig. 1 HTS flywheel energy storage system. Table 1. SPECIFICATION OF PROTOTYPE AND TARGET OF THE FESS Item
Prototype
Power Capacity Bearing
300 kW 100 kWh Rotor: HTS bulk Stator: HTS magnet 4,000 kg 6,000 rpm
Rotor weight Rotor speed
3. DESIGN OF HTS BEARING The levitation force of a cylindrical HTS bulk in magnetic field depends on the shape of the bulk, strength of the magnetic field, and magnetic gradient [1]. The force for the FESS was solved from a magnetic analysis by a generalpurpose simulation program of ANSYS. Five double pancake coils were stacked to levitate the 4,000 kg weight of the 100 kWh prototype model as Fig.2. The analyzed result of the relationship between the levitation force and the maximum field in the coils are shown inFig.3. The levitation force of 39.2 kN (4 tons) is realized by the current load of 74.0 A that generated the maximum magnetic field of 3.4 T
Shinichi Mukoyama et al. / Physics Procedia 65 (2015) 253 – 256
Fig. 2 Layout of five HTS double-pancake coils and a HTS bulk of the HTS bearing of the 100 kWh FESS.
Fig. 3 Analysis result of relationship between levitation force and the maximum magnetic field in the five DP coils.
4. Levitation test of HTS bearing for the prototype model 4-1 Current loading test One HTS coil was fabricated using the HTS REBCO wires with 6 mm in width, which were manufactured by SuperPower Inc.. The HTS coil was the double-pancake coil had an inner diameter of 120 mm and an outer diameter of 260 mm. SuperPower doped pinning centers into the REBCO wires to achieve good high field performance, such as high critical current in a high field. The coil fabrication used the technology of the ‘YOROI coil’ (Y-based Oxide superconductor and Reinforcing Outer Integrated coil) developed by Chubu Electric Power Company [2]. The specifications of the DP coil are indicated in table 2. TABLE 2 SPECIFICATION OF THE HTS DOUBLE-PANCAKE COIL Item
Specification
Wire
Product of Superpower
Width of tape
6 mm
Thickness of tape
0.1 mm
Ic (77K s.f.)
̚100 A
Inner diameter
120 mm
Outer diameter
260 mm
Height of the coil
17.6 mm
The DP coil was installed in the vacuum vessel and was cooled by a first-stage GM refrigerator that had cooling power of 180W at first-stage. A current loading test was conducted by keeping the coil temperature at 54 K. Fig. 4 shows the results of the current loading test. The critical current of the coil had over 110 A, and we confirmed that the DP coils had the satisfied current loading performance at operation temperature of 50 K. 4-2 Levitation test We set up the levitation test configuration that consisted of the five DP-coils and the HTS bulk made by Nippon Steel & Sumitomo Metal Corporation. The HTS coils were stored in the vacuum vessel of low pressure helium gas circumstance. The DP coils were conductively cooled by the GM refrigerator at 50 K and the HTS bulk was cooled by using low pressure helium gas as cooling medium at 53 K. The levitation forces were measured by a load cell on the top of the equipment, and the results are shown in Fig. 5. The levitation force achieved 40 kN, which is the satisfaction force against the targeted force of 39.2 kN for the prototype FESS.
255
256
Shinichi Mukoyama et al. / Physics Procedia 65 (2015) 253 – 256
Coil voltage [μV]
80 70 60
50 40 30 20 10 0 -10 0
20
40
60
80
100
120
140
Coil current [A] Fig. 4 Current and voltage characteristics of one double pancake coil at 54K
Levitation Force(kN)
50
40 30
20 10 0 0
10
20
30 40 50 60 Coil Current [A]
70
80
90
Fig. 5 Result of levitation test of HTS bulk and 5 double pancake coils.
5. Conclusion We verified possibility of the magnetic bearing using REBCO HTS coils through the current loading test and the levitation test by five DP coils and the HTS bulk. After the stand alone test of the bearing, we will embed the HTS bearing into the 100 kWh-flywheel system. Moreover, in order to examine an inhibitive effect against fluctuation in the renewable power source, our team will perform an in-grid test as the FESS will be connected to the mega-solar facility that located in Mt. Komekura in Yamanashi. Acknowledgements This development was a part of ‘Development of next generation flywheel energy storage system’ that included in ‘Development of safe and low cost large scale energy storage system project’ supported by NEDO. Authors appreciate the support from Mr. Nagaya of Chubu Electric Power Co., Inc., and members of Hagoromo Electric Co., Ltd. on coil development and fabrication. References [1] [2]
K. Nagashima, H. Seino, Y. Miyazaki, Y. Arai, N. Sakai, M. Murakami, Force density of magnetic bearing using superconducting coils and bulk superconductorsࠊQuarterly Report of RTRI, Vol. 49 No. 2, 2008, pp 127-132. S. Nagaya, T. Watanabe, T. Tamada, M. Naruse, N. Kashima, T. Katagiri, N. Hirano, S. Awaji, H. Oguro and A. Ishiyama, Develop ment of High Strength Pancake Coil with Stress Controlling Structure by REBCO Coated Conductor, Applied Superconductivity, IEEE Transactions on Vol. 23, Iss. 3, 4601204, 2013