This Project has received funding from the European Union‘s Horizon 2020 research and innovation programme under the grant agreement No 721019
Cost effective FCL using advanced superconducting tapes for future HVDC grids
Started January 1st 2017 (42 months)
Grant Number 721019
FASTGRID project – Context
Context: HVDC supergrids
Today solution: inductance + hybrid breaker
Fully selective solution
hybrid breaker500 kV – 3 kA – 25 kA
(9x7x13 m3 – 80 kW – 5 M€?) 150 mH 500 kV DC
Issue with multi-terminal HVDC grids• Absence of zero crossing for current• Strong increase of fault current
“Best” solution for renewable energies to customers
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?SCFCL?
Too expensive with present
values
Grant Number 721019
FASTGRID project – Limitation phenomena by a superconductor
• Characteristic of a superconducting conductor
Voltage (v)
Length(l)
Current(i) Cross section
(A)
•Electric field: e = v/l•Current density: j = i/A
Superconductingnon dissipative state
Superconductor « invisible »
Dissipative stateLimitation mode
Normal state (T > Tc)e = r j
r: normal state resistivity
Grant Number 721019
Current lead
Gas Vaccuumwith MLI
Fluid vessel
Vaccuum vesselFluid
Cryostat
SC element
Switchgear
FASTGRID project – Resistive-SCFCL device
GRIDGRID
Example of SC element(Eccoflow project)
Grant Number 721019
FASTGRID project – Resistive-SCFCL device – Example in AC grid
FCL makes possible a low grid (zero!)
impedance BUT a low fault current.
Graal for grid designers!
GRIDGRID
Grant Number 721019
Introduction - context
Cost of the Superconductor in a R-SCFCL:
CostSC = CSC Ic ℓ SC CSC : cost / m/ Ic( )
Reduction of CSC
Material & larbor
Ic-w perf. & operating temperature => 65/67 K
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Enhancement of Elim
Conductor design (shunt)
Hot spot issue for low prospective faults
New route
CostSC = CSC ka I a
Vlim
Elim
£CSC
Elim
ka I a Va
Grant Number 721019
Introduction - context
R-SCFCL: innovative very interesting device with a real need in grid.
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But:• Conductor too expensive especially for high voltages• A higher robustness welcome• New routes (sapphire) very promising• New quench detection for device• ….
=> project
Grant Number 721019
FASTGRID deliveries
•Advanced REBCO tape
Low standard deviation in term of critical current over the tape length
Critical current higher than 1000 A/cm-w at 65 K (self-field)
Electric field higher than 100 V/m (50 ms)
•Emerging REBCO tape
Tape with enhanced propagation velocity (CFD concept)
Sapphire substrate REBCO tape with ultra high electric fields
•Smart module of a HVDC apparatus
Current and voltage in the range of 0.5/1 kA and 30/50 kV
New functionality such as quench detection through optical fiber
Extensive testing of the module in relevant operating conditions
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Grant Number 721019
THEVA Tape
After optimization of process parameters:• IC-W > 500 A/cm• ∆IC < 5 %
can be produced with high yield
Ic-w ≈ 580 A/cm-w (77 K)=> Ic-w > 1000 A/cm-w (65 K)
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∆Ic (%)14
10
6
2700 725 750
T (°C)
Ic (A)580
500
400
Grant Number 721019
Consequences of the Ic non homogeneity
Z load
E
Z grid
E =Va
I c
min
99 blocks (1 mm, Ic)
Hot spot (x Ic)
i
1 block ( 901 mm, Ic)
150 VRfault
Limitation trigger
Courtesy J. Vialle
I pros =E
Rfault
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Grant Number 721019
Consequences of the Ic non homogeneity
Z load
E
Z grid
E =Va
I c
min
99 blocks (1 mm, Ic)
Hot spot (x Ic)
i
1 block ( 901 mm, Ic)
150 VRfault
Limitation trigger
« Hot spot » regimeCurrent source
Dead short-circuitVoltage source
v2
RRi 2
Reduce ∆IC & Conductor(Shunt) optimization Courtesy J. Vialle
I pros =E
Rfault
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Grant Number 721019
Advanced REBCO tape: Conductor with high electric fields (> 100 V/m) - Basic line
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• Shunt 500 µm Hastelloy® C276
Thermal expansion fits to the tape substrate!
High resistivity per unit length: 1.25 µΩm
Cost & availability
• Bonding Soldered with 5 µm thick Sn
• TapeWidth 12 mm
Substrate: 100 µm Hastelloy C276
Buffer layer: MgO
Superconductor: GdBaCO
Silver: 2 µm
Hastelloy
Hastelloy
Bonding
Design goal: 150 V/m (40 ms)
Grant Number 721019
Advanced REBCO tape: Conductor with high electric fields (> 100 V/m)
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THEVA tape + Hastelloy shunt
Tmax = 300 K
Grant Number 721019
Advanced REBCO tape: Conductor with high electric fields (> 100 V/m) – other approach
silver
hastelloyReBCO
Original tape Tape + shunt Tape + 2x shunt
silver
hastelloyReBCO
silver
hastelloyReBCO
0
100
200
300
400
500
600
0 0.01 0.02 0.03 0.04 0.05
T [K
]
t [s]
Original tape
Shunt 300 µm
Shunt 300 µm double
0
100
200
300
400
500
600
700
800
900
0 0.01 0.02 0.03 0.04 0.05
T [K
]
t [s]
Original tape
Shunt 300 µm
Shunt 300 µm double
100 V/m 150 V/m
• High thermal capacity,• Electrically insulating layer
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Courtesy F. GomoryCourtesy F. Gomory
Grant Number 721019
Advanced REBCO tape: Conductor with high electric fields (> 100 V/m) – other approach
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• Thermal stabilization in form of 200 µm composite coating Stycast + SiC (20-25 vol. %)• High thermal capacity• Electrically insulating layer• Ceramic filler for compensation of thermal expansion
coating
due to epoxy matrix
Normalized electrical resistance (indicating tape temperature) as function of Joule heat absorbed by the sample (a) and time (b) measured during limitation test (50 ms DC pulse, 100 V/m) of not modified and modified THEVA tape with Stycast – 20 % SiC.
• Testing of resistance against thermal shocks
• Stycast + 25 vol. % SiC • withstands 100 thermal
cycles from LN2 to 150 °C
• Flexible coating with possible bending up to 8 cm diameter at RT
• Improved limitation behaviour
Grant Number 721019
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Emerging REBCO Tape: Conductor with Current Flow Diverter Architecture
Hastelloy/MgO/ GdBa2Cu3O7−δ
Hastelloy/MgO/ GdBa2Cu3O7−δ /Y2O3
Hastelloy/MgO/ GdBa2Cu3O7−δ / Y2O3 /Ag
Uniform Tape Cross section
1. Oxolutia Ink Jet Printing
2. Silver Deposition
Buffer layer
Substrate
HTS ReBCO ( ~ 3 µm )
HTS-Shunt interface
Shunt Stabilizer (1 µm )
0. THEVA bare tape
High Resistance layer
CFD Tape Cross section
IJP (OXO/ICMAB) particularly fit to pattern customized tracks Central isolating part: Y2O3 130 (nm)
Overcome destructive hot-spots for current faults near the critical current by Boosting the Normal Zone Propagation Velocity (NZPV).
NZPV can be increased
0.5 m/s to 15 m/s (x 30)
Grant Number 721019
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Emerging REBCO Tape: Conductor with Current Flow Diverter Architecture
Theva Tape
with CFD
architecture
CFD region
THEVA tapes have shown that the CFD architecture can be incorporated in 12 mm HTS 2G tapes without changing the superconductor properties of the REBCO layer. Optimized processing and superconducting properties.
CFD
region
Homogeneous Ic = 590 A/cm
CFD
region
MgO
Y2O3
Gd123
Hall effect imaging
Grant Number 721019
Emerging REBCO tape: sapphire substrate
Thick YBCO layer grown after IJP deposition on polished crystals
(Ic > 220 A/cm-w)
Implementation on non-polished sapphire substrates under way.
Ultra high electric field tapes (> 1000 V/m) expected.
> 2000 V/m on 1 mm thick substrate (3000 V/m expected)
Ink Jet Printing: customization of conductors for FCL
CSD growth of thick YBCO layers on Sapphire
Sapphire substrate
YSZ -Sputtering
CSD-CeO2
CSD-YBCO
Coated Sapphire substrates18
5cm
Grant Number 721019
Smart module of a HVDC apparatus: 50 kV – 1.2 kA module
Coated Sapphire substrates19
Top 67 K
Bath pressure (abs) 2.5 bar
Pancake voltage 5 kV
Number of pancakes 10
Number of conductors 2
Operating current 1.2 kA
Critical current 2-2.5 kA
Clearing time 30 ms + 20 ms
Tmax 500 K
Elim (target) 150 V/mCourtesy G. Escamez
Hastelloy (100 µm)
SC 3 µm
Hastelloy (500 µm)
Optical fiber Kapton
Module of a high voltage device
Grant Number 721019
50 kV demonstrator: FCL + CB testing
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Technical lock: no laboratory exists with a high power source of 50 kVdc
From realistic Grid constraints To laboratory testing with representative conditions
Test proposal with a 50 kV ac source to represent the current and voltage stress at the limitation and
current interruption instants
Current in FCL
Current in FCL
Grant Number 721019
Conclusions
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• High Ic tapes & operation at 65 K (1000 A/cm-w)
• Hot spot issue to be carefully studied
• High Electric field under limitation (> 100 V/m)
• High Ic homogeneity (5 % already reached by THEVA)
• Enhancement of NZPV
• Current flow diverter (realization through Ink Jet Printing)
• New route: sapphire substrate based tapes
• Successful short tapes, Elim > 2000 V/m measured
• 50 kV – 1.2 kA module
• Quench detection and temperature through fiber glass
• Works on electric insulation & winding configurations
H2020 FASTGRID project started January 1st 2017 with objective to reduce the cost of the REBCO tapes
Grant Number 721019
http://fastgrid-h2020.eu
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