15 - Development of HTS High Current Cables and Joints for DC Power and High Field Magnet Applications

Transcription

1 15 - Development of HTS High Current Cables and Joints for DC Power and High Field Magnet Applications Joseph V. Minervini, Makoto Takayasu, Franco Mangioarotti, Leslie Bromberg, Phillip Michael, Michael J. Cheadle, John G. Brisson MIT Plasma Science and Fusion Center 11 th EPRI Superconductivity Conference Houston, TX October 28-30, 2013 Funded in part by the Low Carbon Energy University Alliance, Tsinghua University

2 Contents Twisted Stacked Tape Conductor (TSTC) DOE Fusion Base Program, and Phase 1 & 2 STTR (MIT/Supercon) CORC DOE Phase 1 & 2 STTR (MIT/ACS) Fusion Magnets with Demountable Joints DOE Fusion Base Program HTS/MgB 2 Microgrid LCUEA-Tsinghua/MIT/Cambridge U. Efficient and Lightweight Current Leads Air Force Phase 1 & 2 STTR (MIT/Creare) Low Cryogenic Load, Light DC Distribution System Air Force Phase 1 & 2 STTR (MIT/Creare) 2G HTS DC Power Cable for Data Center Applications NYSERDA Proposal-MTech, DataGryd, SuperPower, Cryomech, ACT, MIT 2

3 REBCO TSTC Development Work Basic elemental conductor development o o Basic cables made of 4 mm 6 mm width REBCO tapes Multi-tape conductor Twisted Stack Tape Conductor (TSTC) Soldered Cable

4 4

5 5

6 6

7 7

8 8

9 CORC cables for dc-power transmission Collaboration with Tim Haugan, AFRL: - 79 tapes in 17 layers - 2-phase configuration - cable O.D. 10 mm Phase 1 Phase 2 76 K (liquid nitrogen): I c (Phase 1)=3745 A; I c (Phase 2)=3816 A I c (total)= 7561 A

10 CORC cable for fusion magnets Phase II Technology & Engineering Division CORC triplet rated at potentially 3 x 5 ka = 15 ka at 4.2 K, 19 T. CORC 6-around-1 rated at potentially 6 x 5 ka = 30 ka at 4.2 K, 19 T. Phase II STTR DOE-Fusion Energy Sciences Award DE-SC

11 Progress with the CORC cable winding machine - Capable of lengths >100 meters. - Initially winding layer-by-layer. - Fully automated. - Fine control allows for precise winding angle and tension. First dummy cable wound on October 26! DOE - Office of High Energy Physics grant DE-FG02-12ER41801

12 Innovative tokamak design by MIT Fusion Reactor Design class Small reactor: 3.3m major radius Steady state, ~270MWe High B: 9.2T on axis Demountable TF coils Liquid FLiBe blanket I-mode plasma High efficiency RF heating Fusion Engineering and Design 87 (2012)

13 Innovations to overcome structural challenges D-shaped TF coils, YBCO cables, SS316LN structure Top joint supported by Tension Ring Middle joint supported by bolts Central column wedged & buckling against CS and epoxy plug

14 Demountable joint concept: resistive multitape copper pins YBCO TSTC tapes are soldered to a helical termination tape inside a copper tube. YBCO TSTC Cu Tube Former YBCO termination tape Structural plates provide the clamping structure and hold the shunting superconducting cables Structural plate with sc cables Copper pins YBCO termination [Takayasu] TF structure

15 Demountable electrical joints are key design element Can operate at 20K for lower thermodynamic cost of cooling Comb style electrical joint: Good balance between contact area and joint space Out-of-plane forces apply pressure to the joint

16 Preliminary measurements of comb style joint Preliminary, small scale results for 4mm wide tape at 77K and self field: Average: 30 μω mm 2 Extrapolated to 12mm wide tape, 10mm long joint: 11 kw total heating power in TF system at low temperature (20K) 800 kwe required for cooling

17 Alternative design: window-shape TF composed by four straight legs Larger structure to support Lorentz load Same central column concept as D-shape Sliding perpendicular edge joints 720 kw power dissipation at low temperature (20K) 50 MWe required for cooling

18 Efficient and Lightweight Current leads* L. Bromberg 1, A.J. Dietz 2, P. Michael 1, C. Gold 2 and M. Cheadle 1 1 MIT Plasma Science and Fusion Center, Cambridge MA USA 2 Creare Inc., Hanover, NH USA *Supported by the US AFRL

19 Goals of program Design, construction and preliminary testing of current lead and cable 4.62 ka, one pair of 4 Demonstrate cryogenic load reduction by using multiple temperature stations: 140 K and 50 K Design, build and test Efficient, Compact Heat Exchangers Optimization of design for minimal pressure drop and minimized temperature difference with the gas. Manufacturing of a robust cable made of HTS tapes Design and testing of demountable joints for terminations

20 Multiple stage current leads 65 K

21 High temperature HX s Copper foams Downstream Plenum Upstream Plenum Copper fins Inlet and outlet are welded to cover Cover is then welded to sides

22 Copper foam HTS shunt tapes Mechanism for mechanically loading joint section Cold finger for removing heat from joint area Instrumentation HTS shunts soldered to slots in body HTS shunts

23 Low temperature HX Fins Prior to epoxy application Post epoxy application Brazed Copper foam Soldered

24 Low temp HX Path lines

25 SC HX SC shunts between copper and cable demountable cable Cold finger for cooling joint HTS shunts Slotted array with soldered HTS shunts

26 Straight cable before twisting (carpet-stack) Twisted stack cable

27 Fabricated demountable joint

28 Superconducting Power Transmission for Directed Energy Applications A.J. Dietz, K. Cragin. C. Gold L. Bromberg 16th US-Japan Workshop on Advanced Superconductors University of Dayton, Dayton OH July 17, 2013 Supported by the AFOSR

29 Low cryogenic load, light DC distribution systems Collaboration between Creare Inc (Hanover NH) and PSFC at MIT Use two-stage current leads for minimization of the cryogenic loads Intermediate temperature ~ 140 K Lower temperature ~ 55 K Two-state turbo-brayton cycle minimizes system weight and increases cooling efficiency Neon gas optimizes the cycle

30 Two-Stage Turbo-Brayton Cryocooler Cools Multistage Current Leads

31 Test setup 2 independent loops to simulate the turbo-brayton system

32 Testing setup

33 Demountable joints at terminations

34 Testing Testing at 50 K at 5 ka Redesigning the system for 40 ka, 20 K operation 3 temperature stations 140 K 50 K 20 K Testing MgB 2 or HTS cables at high current

35 MIT/University of Cambridge/Tsinghua DC HTS/MgB 2 Microgrid Leslie Bromberg, Michael J. Cheadle, Phillip Michael, John G. Brisson MIT Bartek A. Glowacki University of Cambridge Xiaohua Jiang, Rong Zeng Tsinghua University Funded in part by the Low Carbon Energy University Alliance (LCEUA), Tsinghua University

36 Objectives Design of a 300 m DC microgrid, 1 ka, 5 kv, from the State Laboratory for Renewable Energy to the State Laboratory for Electricity Generation (in Beijing) Rigid, 2-stage cryostat i.e., could not afford Nexans (two stage) Bipolar cable MgB 2 at 20 K HTS, at 77 K, was too expensive System to be installed: scaled down to ~30 m, 1 ka, 1 kv (primarily for cost reasons) Two conductors: YBCO (SuperPower) and MgB 2 (Columbus) He gas cooled at 20 K 36

37 Cold Box Cold Box Load Technology & Engineering Division Schematic of Cable Layout PS Cryostat 77K He 20K He 30 m 24m MgB 2 and YBCO conductor inside rigid cryostat Nitrogen vapor-cooled copper leads with HTS leads to 20K Sumitomo, two-stage GM cryocooler Circulation fan for helium loops at 2 MPa (20 bar!) Recuperator for thermal isolation

38 Helium Circuit Two-stage cooling 59 K and 12 K Helium coolant 4 g/s and 0.4 g/s Pressure = 2 MPa Single cryofan with recuperator Sumitomo RDK415 cryocooler Recuperator for thermal insulation with bypass valve for cooldown

39 Cryostat Cross-Section 23.5 m, rigid, two-stage cryostat (80 K and 20 K) Separate supply/return lines minimizes recuperation & Lorentz force Central tube in each carries a SC cable and helium gas Structural supports and insulation not shown

40 Superconducting Cables MgB 2 : Ic: 6 ka - six reacted strands around copper former Not soldered, twisted 1000 A at 20 K per strand YBCO: Ic: 6 ka - six 4 mm wide tapes twisted and stacked Twisted-stacked 1000 A at 20 K per tape

41 MgB 2 cable U. of Cambridge Provided by Columbus SC 0.9 ka at 0.5 T in each strand 37 filaments, 1.5 mm diameter No copper in the original strands! Copper mandrill Maximum twist pitch 1.5 mm core: 140 mm twist pitch 6.5 mm core: 200 mm twist pitch Protection? At 1 ka, ~ 0.5 s for quench detection 41

42 YBCO cable - MIT Developed at MIT (Makoto Takayasu et al. ) Stacked and twisted cable 6 Superpower 4 mm tapes, between two copper tapes Twist pitch about 200 mm Protection: About 5 seconds allowable for detecting quench. COST: About the same number of MgB 2 as YBCO tapes, at 20 K in self field You can calculate the cost differential for the cable, depending on your bias. 42

43 CORC vs twisted stacked cable Low field, <B_perp> ~ 0.3 T Current carrying capability decreased by ~8% CORC requires ~ 30% more conductor than axial cable CORC cable ~ 20% more expensive than twisted stacked cable At low temperature, twisted/stacked cable less expensive, but not as flexible Twisted/stacked cable more difficult to integrated in a cryostat/cable arrangement. 4 mm tape Bperp Ic (A)

44 2G HTS DC Power Cable for Data Center Applications NYSERDA Proposal MTech, DataGryd, SuperPower, Cryomech, ACT, MIT 44

45 Program Project Team: MTech (Prime), SuperPower, Cryomech, DataGryd, ACT, MIT Design, build, install, and test a 5000A, 48V DC 2G HTS cable running vertically between two floors. Two (+/-) cable lengths of approximately 17.5 m. Operating temperature is ~50 K with cold helium gas as the cooling medium flowing in a closed loop consisting of the 2 parallel cables. Demonstrate continuous operation for 6 months delivering power to a dummy load of servers (not in service). Vary power level of load. Demonstration site will be a commercial data and telecomm server center operated by DataGryd in a facility located at 60 Hudson Street, New York City, NY. 45

46 DataGryd Site 60 Hudson Street, New York City, NY 46

47 47 Schematic Overview of 2 Floor S/C Power Transmission Line