Development and In-Grid Demonstration
of a Transmission Voltage
SuperLimiterTM Fault Current Limiter
Superconductivity for Electric Systems Peer Review
July 29-31, 2008
1
SuperLimiterTM
Outline
• Program, Objectives, Organization and Schedule
• FY2008 Accomplishments and Results
• FY2009 Planned Performance and Milestones
• Summary
2
Project Objectives
• Develop 2G wire based on standard insert
• Develop reliable HTS switching elements
• Develop and fabricate FCL system
- based on conventional utility standard relay,
protection, DAQ, and communication systems
SCE Valley Substation
• Select high reliability cryogenic system with low
operating and maintenance cost
• Single phase high voltage demonstrator test
• Test 3 phase FCL to appropriate standards at an
accredited laboratory under utility supervision
• Install and operate SuperLimiter FCL in the SCE grid
The program develops and demonstrates a commercially viable 3 phase
transmission level FCL in the SCE Grid
3
SuperLimiterTM Major Elements
Cryostat sized for
modular expansion
Valley
Substation
138kV termination in
operation at LIPA site
Insulation
Stainless Strip
HTS Film
NiW Strip
Solder
Cooling System Similar
to Navy Motor Program
N+1 Redundancy
Bifilar 2.2 MVA medium voltage
module tested Jan. 2007
1.2 cm insulated HTS tape
based on standard insert
Design based on validated components is designed for modular expansion
4
Project Team
• AMSC has supplied wire for 6 FCL programs and has orders for
or installed over 7 GW of power equipment
- System Engineering, HTS Wire
• Southern California Edison has integrated HTS FCL in its grid
- Requirements, System Integration, Test Site
• Siemens has developed wire and element based FCL systems
- FCL Modules, System Modeling
• Nexans has provided transmission voltage level terminations
for HTS systems
- Terminations, High Voltage Design
• Los Alamos National Laboratory - strong background in
power systems, FCLs and HTS wire
- AC Loss Measurements
• TCSUH largest multidisciplinary university superconductivity
and advanced materials research effort in the US
- Wire Characterization
Utility Advisory Committee
• San Diego Gas and Electric
• Pacific Gas and Electric
• California Energy Commission
• New York ISO
• Con Edison
• LIPA
• Bonneville Power Administration
• California ISO
• University of California – California
Institute of Energy Efficiency
The program uses Team experience to prove transmission level FCL
5
FCL Operating Principle
During fault
conditions,
superconductor
becomes resistive
and with reactor,
limits current
Supply Bus
Normal State
Resistance
Virtual Switch
Superconductor
Under normal
conditions, power
flows through
superconductor with
virtually no impedance
and system is
Physical Switch
electrically “invisible”
Shortly after fault
clears, power resumes
flow through
superconductor
Reactor
Physical
switch opens
to protect
FCL system;
reactor
maintains
current
Load Bus
FCL system operation is based on simple operating principles
6
SuperLimiterTM Overall Schedule
SuperLimiter Program
2008
4
1
2
3
2009
4
1
2
3
2010
4
1
2
3
2011
4
1
2
3
2012
4
1
2
3
4
Phase 1a Design
Model SCE site
FCL wire development
Switching module development
Full size FCL termination
manufacture and test
Preliminary and detailed system
design
Phase 1b 1 Phase Demonstration
Manufacture 1 phase FCL
Laboratory test 1 phase FCL
Phase 2 Manufacture and
In-Grid Demonstration
3 Phase FCL system manufacture
System laboratory test
In-grid testing
Component Validation
Detailed Design
Single Phase Test
3 Phase In-Grid Test
The 3 Phase program validates the system at 115kV in the SCE grid
7
SuperLimiterTM Phase 1a Milestones
HVD1
WS1
WS2
WS3
Milestone
Phase 1a
Date
Detailed PSS/E model n SCE site
15-Sep-08
Analysis verified and accepted by SCE
8-Sep-08
Wire delivered to Siemens with appropriate
certifications
Slitting and lamination capability,
lengths produced meeting
specifications
Testing capability for
characterizing wire, AC loss
characterization of coils
Demonstrate switching module
production capability meeting
required specifications
15-Sep-08
10-Dec-08
HVD2
Preliminary design review
complete
Complete
HVD3
Phase 1a detailed design review
14-Nov-08
HVD4
Summary report on Phase 1a
31-Dec-08
Verification Method
Approved AMSC wire test procedures and
certified test reports, approved LANL bifilar coil
AC loss test procedure.
Results of power tests and BIL tests. Fab and
testing capacity demonstrated
Interface of termination design accepted by
AMSC and Siemens. Preliminary design
drawing of the system.
Meeting conducted HV subscale test of 1
termination with connection simulation to
bushing validated.
Report delivered to DOE
8
SuperLimiterTM
Outline
• Program Objectives, Organization and Schedule
• FY2008 Accomplishments and Results
• FY2009 Planned Performance and Milestones
• Summary
9
SuperLimiterTM
FY2008 Accomplishments and Results
• AMSC – Bruce Gamble
- System Design
- Wire Development
- Refrigeration
• SCE – Syed Ahmed
- Grid Integration
• Siemens – Wolfgang Schmidt
- Module Design
- Performance Modeling
- Test Results
• Nexans – Frank Schmidt
- Termination Design
- Testing
10
Basic Specifications
Requirement
Prototype
System
Production
Units
Nominal Voltage
115kV rms
115-138kV
Insulation Class
138kV
138kV
Reactor
Sized to Limiting Requirements
Load
Opening Switch
Nominal Current
1,200A
>2,000A
Maximum Site
Unlimited Fault
Current
63kA
>80kA
Site Limited
Current
40kA
Source
Switch
Control
FCL Vessel
Assembly
As required
by customer
Refrigeration
System
Protection and
DAQ System
Trip Current
1.6pu
As required
by customer
Power
Heat
Team has approved a working specification for system
11
Wide FCL Wire Developed
0.075x12.0mm SS Lamina
10.0mm wide 2G HTS
Sn/Pb/Ag Solder
Attributes
Average laminated wire thickness
Laminated wire avg width range
Room Temperature axial resistance
Room Temperature axial resistance
Min tensile strain (77K)
Double bend tolerance
Ic range over 1 m serial lengths
Average wire Ic
Criteria
0.26 +-0.03 mm
12 – 12.4 mm
Result of 5x10m shipment
met
met
Ω/m
0.09-0.12
(R emax-R emin)/R emean = 10%
met
met
0.30%
95% Ic retention @50mm
met
met
(Imax-Imin)/Imean <= 20%
Ph 1A prototype wires
Target 200 A end of 1A
met
up to 173 Amps
(350 A for Ph 1B & 2)
FCL Wire performance on track for this phase
12
Two-in-hand Substrate-to-Substrate Configuration
Used in FCL Bifilar Coils
Two-in-hand Configuration
HTS
• Substrates are shielded,
ferromagnetic loss is eliminated
Tape 1
NiW
Substrate
• Losses close to Norris strip model
Tape 2
HTS
• Three bi-filar wound coils measured
Wire Transport AC Loss Measurement
- Bifilar configuration further reduces
loss
- Includes one 2-in-hand wound coil
LANL
1.E-03
Q (J/m/cycle)
• Q=650 W/phase extrapolated from
coil data
1.E-02
Single
Tape
1.E-04
50 Hz Tape 1
110 Hz Tape 1
1.E-05
50 Hz Tape 2
Norris model for strip
Two-in-hand
Configuration
1.E-06
Single tape 50 Hz
1.E-07
10
100
1000
Ip (A)
Extrapolated FCL wire losses are a fraction of total phase refrigeration load
13
SuperLimiterTM Operating Conditions
•Constraints
-No bubbles around the bottom of bushing – sub-cooled LN2
-Termination dielectric requirement P > 3bar
-Fast recovery time – saturated LN2
FCL Vessel
Assembly
•Solution
-Operate FCL in sub-cooled LN2 with nominal operating
temperature lower than design point.
• FCL design at temperature 74K@5bar(a), but operate at
temperature 72K@5bara
• Temperature margin determines the number of faults the system
can absorb before system is off-line to recool
• 2K margin allows LN2 to absorb 57MJ energy (~6 faults)
• 5 bar pressure will allow LN2 in coil vicinity absorb fault energy
without bubbling
Refrigeration System
Power
Heat
FCL operates at high pressure sub-cooled LN2 temperature
14
SuperLimiterTM Refrigeration System
Heat Load
Value (W)
Cryostat
850
Other Refrig. System
200
Terminations
900
Lines, Valves, Bayonets
350
AC Losses
1950
Total Max. Predicted
4250
Planned Capacity
6000
• AMSC has operated HTS systems in utility/harsh industrial conditions
- LIPA and TVA/SuperVAR Project
• DOE-FCL system based on lessons learned in those systems
- Phase 1b – open cycle option shown above
- Phase 2 - replace with closed cycle modification
• Simplified, COTS based system
• Significant margin planned for prototype system
Refrigeration based on experience at LIPA and other AMSC utility HTS systems
15
SuperLimiterTM
FY2008 Accomplishments and Results
• AMSC – Bruce Gamble
- System Design
- Wire Development
- Refrigeration
• SCE – Syed Ahmed
- Grid Integration
• Siemens – Wolfgang Schmidt
- Module Design
- Performance Modeling
- Test Results
• Nexans – Frank Schmidt
- Termination Design
- Testing
16
SCE Profile
• 50,000 Mile2 Service Territory
• 120 years of service
• $17 Billion T&D Assets
Distribution
• 85,000 Circuit Miles
• 690,000 Transformers
Customers
• 4.7 Million Meters
• 13 Million
Customers
• 22,889 MW Load
Transmission
• 12,600 Circuit Miles
• 4,200 Transformers
SCE is one of the largest utilities in the United States
17
SuperLimiterTM Southern California Edison
• SCE is investing in the future
- > $3 billion invested in T&D over the last five years
- $11 billion planned infrastructure investments over the
next decade.
• SCE has considerable experience with
superconducting Fault Current Limiters
- Since 1993 in DOE-SPI, tested a 15kV FCL in 1999
- SCE role in this program is
• Specifying requirements
• Providing the prototype operation site
• 138 kV Transmission Voltage level FCL addresses
- Elimination of CB and other equip. replacement
- Enhanced reliability, shorter customer outages
- More stable, higher-quality electricity supply
- A “self-healing” grid
July 1999: FCL at a Southern California
Edison substation
SCE has unique experience with HTS FCL technology and this program extends
this to transmission voltage levels
18
SuperLimiterTM Demonstration Site
• Selection criteria
Riverside
- Voltage
- Transmission planning
- Civil engineering
• Valley Substation selected
• Located near Riverside, CA in a
desert climate
Valley
Substation
• Analysis used to select bus tie
application
• Significant load growth planned
over the next 10 years
- Tapped external reactor
enables device to easily adapt
The Valley Substation is selected
19
SuperLimiterTM Test Site
Present Installation:
Inland Empire
• 4-3Phase, 336/448/560 MVA
525-120 kV, OA/FOA/FOA
Transformers.
• Sectionalized 115 kV bus each section fed by 2
transformers
Devers
500 kV
Serrano
500 kV
“A”
“B”
500 kV
• Max. single-phase-to-ground
fault = 30 kA
• All 115 kV CBs rated 40 kA
Planned Future Installation:
• Load growth in the area and
interconnection of new
generators will require
additional transformers
• Fault current duty will rise
above 40 kA
“C”
115 kV
115 KV
Outgoing
1000 MW
Feeder
Future Gen
(Studied)
Bus Tie
(Selected)
“AB”
115 kV
115 kV
A bus tie application at the Valley Substation is selected
20
SuperLimiterTM Grid Integration Models
• If the parallel reactor is optimized for the location, a greater reduction
is achieved
Location
Fault current before
Ipeak
Irms
Inductance
Fault current after Reductions
Ipeak Irms Ipeak Irms
Outgoing Feeder Load side of fault 52.7
19.2
5.35 mH
37.2 12.4
Bus Tie
Bus Tie
29.9
29.9
8.10 mH
8.10 mH
71.0 25.0 12.56% 16.39%
69.6 24.3 14.29% 18.73%
Valley 115kV bus "AB"
Valley 115kV bus "C"
81.2
81.2
29.5%
35.4%
* Current in kA
The flexibility afforded by the external reactor permits performance optimization
and re-optimization following future system changes
21
SuperLimiterTM
FY2008 Accomplishments and Results
• AMSC – Bruce Gamble
- System Design
- Wire Development
- Refrigeration
• SCE – Syed Ahmed
- Grid Integration
• Siemens – – Wolfgang Schmidt
- Module Design
- Performance Modeling
- Test Results
• Nexans – Frank Schmidt
- Termination Design
- Testing
22
Siemens‘ Experience in Resistive Limiters
Development of the resistive type SFCL for medium voltage based on
high Jc YBCO thin films started at Siemens in 1992.
1992
1996
YBCO on IBAD buffered
YSZ substrated
1997
100 kVA model,
4-inch-substrates
YBCO on sapphire
2001
1.2 MVA; 7.2 kV
2004
0.9 MW; 900 V-DC
100 x 200 mm
YBCO on sapphire
2007
2.25 MVA; 7.2 kV
AMSC 2G wire
344S superconductors
23
Switching Module for the HV SFCL Project
Main design characteristics
• The switching module comprises
3 parallel x 17 series = 51 bifilar
pancake coils per phase
• Two in hand winding with 12 mm
wide wire to increase the current
Alternating current
directions between
adjacent turns of
bifilar coils cancel
most magnetic
fields
Regions stressed by
BIL tests, numbering
see next slide
• Improved electrical strength due to:
- Insulated wire
- New contact design
- Corona rings around the coils
• Horizontal stack with radial supports
between module and cryostat wall
(1)
(2)
(3)
(1)
24
Performance Modeling and Testing
Voltage insulation considerations
(1) Corona ring to vessel. Modeling at
University of Braunschweig to determine
Emax; measurement on mockup.
y in m
|E| in 106 V/m
0.4
6
(2) Surface flash over along radial supports.
(3) Within a coil if one terminal is grounded
after a first lightning strike and a second
strike applies a voltage along the normal
conducting tapes:
0.3
4
0.2
2
0.1
- Turn to turn
0
0.4
0.0
0.2
0.1
0.3
- Contact to tape (weakest part within coil):
x in m
Breakthrough voltage > 20 kVrms in air at 1
Electric field distribution at
bar, even after 60 switching events.
650 kV between module
and wall
25
Performance Modeling and Testing
Electrode diameter = 100 mm
Voltage insulation considerations:
Radial supports
Surface flashover along the radial
supports could lower the breakdown
voltage (BD) under lightning impulse test.
The University of Braunschweig started
small scale BD voltage measurements in
air and liquid nitrogen to select an
appropriate material for the supports.
Sample diameter = 40 mm
Average Breakdown Field Strength
14.28
16
14
kV/mm
First results:
• Significant dependence of BD on
material in liquid nitrogen. Less
dependence on surface finish.
• 10 mm short sample seems not to
reduce BD field strength in air.
11.40
12
12.29
8.84
10
8
6
4
2.55
2
0
10mm
PMMA
polished,
air
5mm
10mm
10mm
10mm
PMMA
PTFE
PMMA
PMMA
polished, machined, polished, machined,
LN2
LN2
LN2
LN2
26
Performance Modeling and Testing
Switching
2000
400
1000
200
0
0
-200
-1000
Voltage (V)
Current (A)
• First tests on a 3 m sample of 12 mm wide HTS-wire:
Critical current 167 A @ 77 K, 258 A @ 72 K
77 K, sat., t: 100 ms
• More than 60 switching test in saturated (77 K)
and sub-cooled (72 K, 1.2 bar) LN2
72 K, 1.2 bar, t: 500 ms
T: ~72 K
-2000
0
10
20
30
Time (ms)
40
-400
50
27
Performance Modeling and Testing
Resistance ratio (%)
Recovery time
• About 12 - 15 sec measured on full size dummy coil in sub-cooled LN2
• 12 mm wide dummy wire insulated with wrapped Teflon tape
• Amount of LN2 available for cooling restricted by appropriate enclosure
to simulate adjacent coils
110
T: 77 K, p: 1 bar
T: 72 K, p: 1.2 bar
100
90
80
70
60
-0.05
10
0
20
Time (s)
28
SuperLimiterTM
FY2008 Accomplishments and Results
• AMSC – Bruce Gamble
- System Design
- Wire Development
- Refrigeration
• SCE – Syed Ahmed
- Grid Integration
• Siemens – Wolfgang Schmidt
- Module Design
- Performance Modeling
- Test Results
• Nexans – Frank Schmidt - Work done by Nicolas Lallouet
- Termination Design
- Testing
29
NEXANS experience
High voltage & Superconductivity
• NEXANS is one of the major worldwide leader in the cable industry,
including high voltage cable system.
• Since 1997, NEXANS is involved in superconductivity and has developed,
within the frame of the LIPA 1 project, a complete high voltage
superconducting cable system including its high voltage accessories.
• LIPA 1 project has involved two world records:
- Longest superconducting cable ever installed
- Highest voltage used in a superconducting cable system (cable & accessories)
• NEXANS experience on high voltage accessories developed within the
frame of this project is the basement for the Fault current Limiter
termination development.
30
NEXANS experience
LIPA cable & accessories type test
LIPA terminations design is the baseline of the FCL termination and was
validated by type tests in 2006 (NEXANS Hanover laboratory test)
• Validation of 138 kV level according
IEC 60840:
9 190 kV / 30 min
9 Partial discharge < 5pC at 114 kV (after 1 min
at 140 kV)
9 Lightning impulse test 650 kV (10 shots + & -)
• Validation with current
9 Load cycle (100% 8 hours – no current 16
hours during > 20 days)
9 Termination designed up to 2400 A but
several tests at higher current
Specifications in accordance with FCL project
31
NEXANS experience
Superconducting cable system connected on LIPA grid
• Cable system installation in Long Island in 2007
• 3 phases
• 600 m of cable
• 6 terminations
• Connected to the grid since 22th April 2008
• 138 kV level
• No problem identified in cables & terminations since
energization
High voltage accessories for superconducting
system validated in laboratory and inside real grid
32
FCL termination design
Adaptation of LIPA termination
LIPA termination part insuring thermal & electrical transition between
cryogenic and ambient temperature is transfer to FCL termination design
33
FCL termination design
Adaptation of LIPA termination
LIPA termination part insuring the thermal & electrical transition between
cryogenic and ambient temperature is kept for FCL termination design
Connection to the grid
Insulator:
• Electrical field management at ambient temperature
Transition insulator / intermediate enclosure:
• Thermal stabilization at ambient temperature
• Tightness insulator / intermediate enclosure with ambient
atmosphere
Intermediate enclosure:
• Management of thermal gradient
• Management of electrical field at cryogenic temperature
• Tightness with pressurized liquid nitrogen
Inner vessel interface (liquid nitrogen):
•Main change with LIPA design
•New electrical connection component
•New electrical field distribution
•Small thermal impact on termination bottom
34
FCL termination design
Thermal & electrostatic calculations
• Impact of the new cryostat interface has been
checked and validated on the part out of liquid
nitrogen:
9 E field calculation
9 Temperature distribution
• No change on high voltage regarding LIPA project
• Better thermal distribution than LIPA design
(less losses with full current)
Extract of thermal study
Extract of
Electrostatic study
NEXANS
termination
• Part of the termination immersed in liquid
nitrogen has been studied with the new
configuration:
9 E field calculation (3D)
AMSC
Cryostat
SIEMENS
module
• E field distribution less constraining than LIPA design
35
FCL termination design
Overview
LIPA based termination
SIEMENS HTS switching module
Termination part immersed in liquid nitrogen
(new configuration)
Electrical flexible connection
(new component developed)
36
FCL termination design validation
High voltage test preparation
- Full scale assembly achieved in NEXANS Hanover testing laboratory:
• All termination components assembled
• New interface with cryostat simulated (more constraining E field distribution than real
design to insure margin)
• New electrical connection to module connected (more constraining E field distribution)
Flexible connection simulated
(connected to the termination bottom & inserted in testing cryostat)
cryostat)
37
FCL termination design validation
High voltage test results
• AC withstand test successfully completed
- 190kV / 30 minutes
• Partial Discharge measurement successfully completed
- Voltage increase up to 140 kV for few minutes
- Decreasing to 114 kV and measurement
- No PD measured (noise level < 3pC)
• Lightning impulse test successfully completed
- 650 kVp (10 shots in both polarity)
• Switching impulse successfully completed
- Success of the test (540 kVp 250/2500µs – both polarity)
FCL termination high voltage design successfully validated
38
FCL termination design validation
Electrical test – flexible connection to module
- A full scale prototype of the flexible connection to module was also prepared,
tested and validated with nominal current:
• DC resistance measurement @ 77 K
• AC resistance measurement @ 77 K
• Temperature measurement all along this connection
- This connection allows low thermal losses with nominal current (≈25 W)
FCL termination design successfully tested at high voltage and current
39
SuperLimiterTM
Outline
• Program Objectives, Organization and Schedule
• FY2008 Milestones
• FY2008 Accomplishments and Results
• FY2009 Planned Performance and Milestones
• Summary
40
SuperLimiterTM FY2009 Planned Performance and
Milestones
Milestone Description
Date
Verification Method
Phase 1a
WS3
HVD4
Demonstrate switching module
production capability meeting required
specifications
Results of power tests and BIL tests
10-Dec-08 documented to meet specifications. Fabrication
and testing demonstrated.
Summary report on Phase 1a
31-Dec-08 Report delivered to DOE
Phase 1b
WS4
Delivery of prototype switching
modules for single phase test
1-Apr-09
WS5
Delivery of HTS wire for single
phase test
28-May-09
Wire delivered to Siemens with appropriate
certifications
23-Jul-09
HTS switching module shipped to AMSC for
assembly into single phase FCL system.
Records of coil tests complete and sent to
partners.
WS6
Delivery of HTS switching modules
for single phase test
Dummy switching module sent to HV test facility
The 3 Phase program validates the system at 115kV in the SCE grid
41
SuperLimiterTM
Outline
• Program Objectives, Organization and Schedule
• FY2008 Milestones
• FY2008 Accomplishments and Results
• FY2009 Planned Performance and Milestones
• Summary
42
SuperLimiterTM Summary
• Conservative/proven HV design
• Adjustable current limiting without NRE (external reactor)
• Substantial fault current reduction
• Standard 2G insert coil tests demonstrate low ac losses
• Bifilar coil technology already proven at medium voltage
• Voltage and “trip factor” changed by +/- HTS coil modules
• Siemens experience led to a wire based system for reliability
• 138kV termination in use at LIPA and 1st article passed HV tests
• Program on track for testing a single phase in Phase 1b
The SuperLimiter Team experience has led to the selection of a robust modular
design based on validated components
43