Design, Test and Demonstration of Saturable

Design, Test and Demonstration of SaturableCore Reactor HTS Fault Current Limiter
U.S. Department of Energy Annual Peer Review
Crystal City, VA
July 31, 2008
Presenters:
Larry Masur, Frank Darmann, Robert Lombaerde
Presentation Outline
� Program Overview and Team Description – Larry Masur
� Saturable Core FCL Principles of Operation – Frank Darmann
� Analytical Modeling and Experimental Results – Frank Darmann
� FY 2008 Program Progress and Timeline – Bob Lombaerde
� Summary of Accomplishments and FY 2009 Plans – Bob Lombaerde
2
Program Overview
� Five Years / $11 Million from DOE
� End Goal: Design, Build, and Test
Transmission-Class Saturable
Core Reactor FCL
� Intermediate Goal: Design, Build,
and Test Distribution-Class
Saturable Core Reactor FCL
� Saturable Core approach
compatible with 1G wire
3
FY 2008 Objectives
� Validate fault current limiting action
of Zenergy’s first device using fullscale, three-phase testing.
� Validate Zenergy’s analytical
models using scaled laboratory
testing.
� Design a distribution voltage FCL
suitable for installation in a utility
electrical grid.
� Identify and finalize a host utility for
distribution voltage FCL
4
Project Partners
� Zenergy Power plc
� Formed in 2006, London, UK
� Zenergy Power Inc. – formerly
� Founded in 2004, San Francisco, CA
� Zenergy Power Pty Ltd – formerly
� Founded in 1987, Sydney, Australia
� Zenergy Power GmbH – formerly
� Founded 1999, Bonn, Germany
� Los Alamos National Lab
5
Presentation Outline
� Program Overview and Team Description – Larry Masur
� Saturable Core FCL Principles of Operation – Frank Darmann
� Analytical Modeling and Experimental Results – Frank Darmann
� FY 2008 Program Progress and Timeline – Bob Lombaerde
� Summary of Accomplishments and FY 2009 Plans – Bob Lombaerde
6
Introduction:
The saturable core FCL – how does it work?
� Material properties
� The B-H curve
� The Zenergy concept of the saturable core FCL
� Basic core design
� DC magnetisation and Permeability: FEA results
� Core de-saturation during a fault current event
� Basic design equations
� Experimental results
� An approach to optimisation
� The transformer effect
� Transient results + 13kV prototype results
� DOE phase 2 specifications and design
7
Concept:
� The saturated core FCL utilizes the large difference permeability of
magnetic materials;
� High permeability materials allows a low impedance during normal
operation and a very high impedance during fault current events;
� Gives rise to the concepts of “Insertion impedance” and “Fault impedance”
� Insertion impedance defined as the impedance of the device during
normal operation as a fraction of the bus base impedance
� Market directs us to <1% insertion impedance
� Fault impedance defined as the steady state equivalent impedance
which would result in the same fault current limiting effect
� Market directs us to a 50% fault current reduction
8
B-H and µ-H curves
Material property of M3 laminated steel
µr = 55,000
Permeability
Magnetic flux density [T]
Steady state
Faulted state
µr = 1
Magnetic field intensity [A/m]
9
Basic idea:
Low Impedance AC Coil – Large AC Current
AC Coil
Permeable material
AC source
10
Basic idea:
Iron core saturated by coil powered by DC source
High Impedance AC Coil – Small AC Current
AC Coil
DC Coil
High permeable material
AC source
DC source
Low Impedance AC coil – Large AC Current
11
Basic idea:
Implementation of Zenergy Power FCL
HTS DC coil saturates Iron in reconfigured Iron Core
Iron Core
HTS DC coil
AC coil
12
Configuration for single phase FCL:
Dual Iron Cores saturated by one High Temperature Superconductor
(HTS) DC coil
Dual Iron Cores
AC Coil
AC Coil
High Temperature
Superconductor (HTS) DC
coil provides efficient method
of saturating Iron Cores.
13
Configuration for single phase FCL:
Two steel cores per phase
AC Coils connected in series – during a fault, they alternate in and out of
saturation to reduce the current in each half cycle
AC Coil
14
The Six Iron cores for a 3-phase FCL:
One HTS coil to saturate all six cores
15
Pie Core concept
� Build six identical high
permeability cores – use
transformer core
laminations to ensure
good flux transport
around the core
16
Flux density during the un-faulted AC steady state
� Detailed design of this core
structure has been improved
through building and testing
prototypes and FEA,
� Economic core construction
for efficient DC flux transport
is detailed, proprietary art,
� Optimised for low insertion
impedance and high fault
impedance,
� All parameters are coupled –
optimisation problem
17
Steel core flux density at peak of fault current
Note:
� The AC side cores are
now unsaturated
� The DC side cores
remain saturated
� But how do we design
the basic FCL
parameters ?
� What are the
equations involved
for optimisation ?
18
FCL design process:
FCL design and optimisation process
19
Optimisation process:
Summary of inputs and outputs
Inputs
HTS TAPE
- cost / m
- temperature
- -B field
- Ic (B, T)
M AGNETICS
- core dimensions
- material properties
- density kg/m 3
- cost / m3
-
USER REQ’MTS
’’
- Low insertion Z
- High Fault Z
- voltage kV
- current kA
-
USER REQ’MTS
USER REQ’MTS
- Meet Constraints
- Meet Constraints
- Expected values
- Expected values
Outputs
HTS TAPE
HTS TAPE
- Length
- Length
- -total
totalcost
cost
Non-Linear
Non-Linear
N
on-LinearOptimization
OptimizationMethods
Methods
-Electromagnetic
-ElectromagneticModelling/Simulation
Modelling/Simulation
- -Circuit
Modelling/Simulation
Circuit Modelling/Simulation
- -Power
PowerSystem
SystemModelling/Simulation
Modelling/Simulation
- -Linear
Programming
Linear Programmingusing
usingcost,
cost,
size,
weight
size, weight
STRUCTURE
- Transport Dimen.
- Transport Weight
- Voltage standoff
- Current Capacity
-
MAGNETICS
MAGNETICS
- Dimensions
- Dimensions
- Core Geometry
- Core Geometry
- W eight
- Weight
- Total Cost
- Total Cost
STRUCTURE
STRUCTURE
- Meet Constraints
- Meet Constraints
- Final dimensions
- Final dimensions
- Final Weight
- Final Weight
- Final Cost
- Final Cost
SUPPORT
- DC current/ P.S.
- Cryo + cooling
- Aux. Power Req.
- Cooling
-
SUPPORT
SUPPORT
- DC PS Spec.
- DC PS Spec.
- Cryo cooling Spec
- Cryo cooling Spec
- Aux Power Spec
- Aux Power Spec
20
Optimisation process:
Basic DC design equations
Steady state AC design equations
� DC steady state, un-faulted:
(1) Hdc = Hsat + Hac where:
� Hdc = magnetising force required to saturate the core in the presence of the
peak AC steady state, un-faulted current
� Hsat = Saturating magnetising force required (material property)
� Hac = Additional magnetising force to overcome steady state AC coil
magnetisation
� De-magnetisation of AC core during a fault:
(2) Ndc Idc = Nac Ifault . √2 . α where:
� NdcIdc =DC ampere-turns
� α = The AC demagnetising core factor.
� Nac = number of AC turns
� Ifault is the new limited rms fault current
21
Optimisation process:
Steady state AC design equations
� Un-faulted steady state condition – FCL insertion impedance
πf) . 2. Nac2. Acoil. µo . µrel . β
(3) Xins = (2π
≤ 0.01 . Xbase
Where:
� β is a shape factor, strongly dependent on coil height and is determined
experimentally, via FEA, Rogowski, Niwa (1924), correction factors
� Faulted steady state condition – Effective FCL fault impedance
πf) . 2 . Nac . AFe . Bsat / (2 . √2 . Ifault) ≥ Xsource Where:
(4) Xfault = (2π
� Bsat is the saturated field (2.1 Tesla)
� AFe is the cross sectional area of the core
� Xsource = Source impedance of bus being protected
22
Experimental and design:
Electromagnetics
1. Electromagnetic design of steel core, DC coil, AC coils
� These elements are strongly linked
� Take existing bus specifications - Zbase, Zsource, V, Iss
� Tolerated Zins, and the required equivalent Zfault
� Boundary conditions
� Mass: Needs to be transported practically and economically
� Footprint: Integrated into existing sub-station layouts
� Cost: Price < Value to the customer
� HTS performance: Determines coil height, temperature of operation
This is a multi –variable optimisation problem
23
Design optimisation:
Cryogenic considerations
2. Cryogenic design and HTS coil details:
� Coupled with electromagnetic design:
� Strongly coupled: To the performance of HTS tape in a magnetic field;
� Weakly coupled: To thermal loss equations (cryostat, current leads)
� Coupled: Cryogenic cooling technology, efficiency, and cost
� One strategy: Maximise height of HTS coil to minimise Bperp until a boundary
condition is met (cost, mass, height)
� Calculate:
� Steady state AC coil losses and cryostat heat leak;
� Transient AC coil losses;
� Temperature rise of AC coil during a 30 cycle fault, three in succession.
24
Experimental results
Experimental characterisation
process
25
Design optimisation:
Experimental results
Experimental process has involved the following:
� Characterising core DC magnetisation and AC minor loops;
� Characterising FCL insertion impedance;
� Measuring transformer effect and confirming FEA results;
� Gaining insights into the demagnetisation process;
� Characterising the Fault impedance and transient waveforms;
� Confirmation of transient circuit model in PSCAD;
� Harmonic content in steady state and faulted waveforms
26
Experimental results:
Core and coil arrangement
Experimental results:
Insertion impedance vs AC coil height
Xins asymptotes to air
core inductance value of
each coil size
28
Experimental results:
Insertion impedance vs AC coil height
Experimental results:
Measured and Rogowski calculation included
DC
1.0
dc
ac
1.0
Nac = 50, Iac = 4A
Nac = 50, Iac = 6A
Nac = 50, Iac = 8A
Nac = 50, Iac=10A
Nac = 50, Iac = 20A
Nac = 50, Iac = 40A
Nac = 50, Iac = 60A
Nac = 50, Iac = 80A
Nac = 50, Iac = 100A
Nac = 50, Iac = 120A
Measured air core impedance
Calculated air core impedance (Rogowski)
0.9
0.8
Measured insertion impedance [Ohms]
AC
0.7
0.6
0.9
0.8
0.7
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0.0
0.0
0
10000
20000
30000
40000
DC applied Ampere-turns [AT]
50000
60000
70000
80000
30
Experimental results:
Insertion impedance vs AC coil height
Spread of Xins at any bias
tightens with coil height
Experimental results:
Effect of changing number of AC turns
Zins obeys Nac2 .
Spread decreases for
lower Nac
Experimental results:
Steady state fault impedance
1.0
Choose DC bias point and AC coil height for
an equitable balance between:
0.9
Insertion impedance [Ohms]
0.8
Zins , Zfault , mass, footprint, HTS,
0.7
0.6
0.5
0.4
0.3
0.2
Nac = 50, Iac = 450A (Hac = 385mm)
0.1
0.0
0
10000
20000
30000
40000
50000
DC applied Ampere-turns [AT]
60000
70000
8000 0
33
Experimental results:
Transient un-faulted steady state flux density
AC limb flux density excursions in the unfaulted steady state as a function of DC bias.
Vac = 415. Nac=50. Ndc= 100.
2.2
2
1.8
1.6
DC Bias = 35 kAT
1.4
DC Bias = 21 kAT
Flux Density [Tesla]
DC Bias = 10 kAT
1.2
As the DC bias is reduced, the steady state un-faulted flux
density on AC core side starts to approach the knee point
DC Bias = 7.6 kAT
DC Bias = 5.3 kAT
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
Time (s)
-0.6
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
34
Experimental results:
Transient fault currents
Experimental results:
Pure fault limiting from dB/dH effect
Experimental results:
Dispelling the myth
� There has been a common misconception that the saturable core
FCL suffered from a transformer coupling effect between the AC
and DC coils;
� This was based on Raju(1982) and others who showed coupling
between the AC and DC coils;
� Now, we understand that the transformer effect can be minimised;
� We designed experiments before the 13.8 kV prototype testing to
verify our analysis.
37
Experimental arrangement:
Dispelling the myth
38
Experimental results:
Dispelling the myth
AC side core flux density:
Unfaulted steady
state, low impedance
Faulted state,
high impedance
Experimental results:
Dispelling the myth
DC side core flux density:
Faulted state, high impedance
40
Experimental results:
DC circuit current transients
DC circuit current transients. Investigation into AC coil height. 385mm high AC coils.
V ac=240 V. 0.0225 m 2 core area.
700
600
500
Ipeak – Iop = +12% Iop
DC circuit current [A]
400
• Transformer effect exists and we need to be aware of it;
Ipeak -Iop= +300% Iop
300
200
• Passive, intrinsic, good design is required;
100
• Rapid detection and DC circuit isolation not required;
0
DC Bias = 56.8 kAT (385mm high AC coils)
-100
• Zenergy DC power supplies employed have undergone >1300
fault event
tests
without
failure;
DC Bias
= 4.8
kAT
-200
-300
• Zenergy FCL maintains completely passive Time
FCL[s]design.
-400
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
41
PSCAD model:
A six terminal block customer model
developed over 24 months
DC circuit
DC2
Iwith_FCL
BRK1
G
A1
A2
B1
Vdrop
S
B2
I_dc
Customers source
and load details
E_dc
Zenergy Power Pty Ltd Fault Current Controller model
DC1
B
DC
FCL Reactor
Three-limb
Three-phase
MMF
H
St
I_int
C1
C2
Load
L
Eload
42
13 kV / 10 kA prototype
Prototype FCL design:
43
13 kV / 10 kA prototype results:
Prototype FCL design
Test site: Vancouver / Powertech
44
13.8 kV / 16 kA prototype results:
Fault current transient measurements
13.8 kV / 16 kA prospective fault current tests
2
A = 0.02m . Nd c = 800. Idc = 106 A. Nac = 40
36000
32000
28000
21% reduction in fault current
Line current A with FCL
Line current A with no FCL
24000
20000
Current [A]
16000
12000
8000
4000
0
-4000
-8000
-12000
-16000
-20000
0.14
0.15
0.16
0.17
0.18
0.19
0.2
0.21
0.22
0.23
0.24
0.25
0.26
0.27
0.28
0.29
0.3
45
Distribution class design
DOE distribution class FCL
for utility installation:
Design details
46
Specifications and core design
DOE distribution class 56 MVA FCL
Specifications
Value
AC side rated voltage
26 kV
AC side current
1250 / 2000 A
Prospective fault current
30.0 kA
Limited fault current with FCL in circuit
15.0 kA
Base impedance of sub-station bus
12.0 Ω
Source impedance of sub-station bus
0.500 Ω
Transient FCL impedance at 15 kA
0.480 Ω
Insertion impedance at 2000 A AC RMS
0.12 Ohms
Number of AC turns
20
Calculated “saturated” insertion impedance
0.08 Ω (0.7 % Zbase)
47
DC coil optimisation
HTS conductor and coil winding details
*
Cooling
3 x AL330 GM Cryomech
Max design temperature
40 K
Steady state operating temperature
20 K
HTS conductor
Gen 1 BSSCO tape *
Critical current of HTS conductor
125 A ( 77K, self field, 1 atm)
Critical current of HTS coil at 30 K
330A at 30K, 260A at 35K *
Number of HTS conductor turns
1,600
Operating current of HTS coil
200 A *
Steady state losses of HTS coil
21W at 200A DC & Top < 25K
*
*
* Risk mitigation elements
48
Distribution-Class FCL Schematic
1.9 m
49
Presentation Outline
� Program Overview and Team Description – Larry Masur
� Saturable Core FCL Principles of Operation – Frank Darmann
� Analytical Modeling and Experimental Results – Frank Darmann
� FY 2008 Program Progress and Timeline – Bob Lombaerde
� Summary of Accomplishments and FY 2009 Plans – Bob Lombaerde
50
DOE FCL Program
Prospective
Station
Location
51
DOE FCL Program Overview
� Goal: Design, build, test and install a transmission class FCL
� Present design intermediate step: Distribution Class FCL
� Prospective Host Utility providing technical specifications
� Design based on significant modeling/computer simulation
� Passive FCL Design – “auto-reactor”
� Conservative design margins for a reliable product
� Redundant Cryo-system, Redundant DC power supplies
� Oil free design minimizes environmental concerns
� Built in SCADA to monitor and control the FCL
� Easily Transportable
52
DOE Program FCL specifications
� Line Voltage
26 kV
� Steady State Current
1200 A (designed for 2000 A)
� Prospective Fault Current
30 kA
� Fault Current Reduction
40-50%
� Steady State Impedance
<1%
53
DOE Program Timeline – Delivery by end of March
ID Task Name
O
4
Planning HTS FCL
5
Planning Partners
6
Readiness Review
7
Design FCL
8
Build FCL
9
Build and Test Subsystems for FCL
N
D
Half 1, 2008
J F M
A
J
M
Half 2, 2008
J A S
O
N
D
Half 1, 2009
J F M
A
M
Spec requirements
Readiness Review
Design Review Report
Subsystems Qualified
FCL Built...
10 Build FCL
11 3rd Party Transport
Test Data Ready...
12 Third-Party Testing of FCL
13 Site Planning
14 Delivery to Site
15 Plan 3-Φ 138 kV-Class HTS FCL
16 2G tape coil experiments
Today
54
Risk Mitigation Element:
California Energy Commission (CEC) FCL Project precedes DOE Project
� $500,000 grant to install and test Fault Current Limiter (FCL) – May
2007
� Fault Current Limiter to be installed in Southern California Edison’s
Circuit of the Future
55
CEC FCL specifications
� Line Voltage
12 kV
� Steady State Current
1200 A
� Prospective Fault Current 22.4 kA
� Fault Current Reduction
33%
� Steady State Impedance < 1 %
56
CEC Project Timeline – Delivery to SCE by Year End
ID
Task Name
Apr
1
Design
2
Procure Material
3
Assembly
4
Testing
5
Assembly tests
6
Transport to Lab
7
Fault Tests
8
Transport to Utility
9
Deliver to Utility
May
Jun
Jul
Aug
Sep
Oct
Nov
2009
Dec
Jan
57
CEC Project:
HTS coil in cryostat, Evacuation and Cryocooler installation ongoing
58
CEC Project Benefits to DOE Program
� Refine design tools and critical
parameters
� Establish vendors and build
relationships
� Improve testing and test procedures
� Develop experience with cryocooler
system
� Develop monitoring and control
system
� Grid experience with Zenergy’s FCL
prior to DOE program
59
Zenergy Power - 2008 Results Summary
� Successful fault test of prototype FCL – Dec 2007
� Extensive modeling, computer simulation, and experimental verification
� Design and build of Zenergy Power’s first CEC FCL
� Design of second Zenergy Power DOE FCL
� Prospective host utility identified
60
Plans for FY 2009
� Assemble Second Distribution Class DOE FCL subsystems – 1Q09
� Third Party test DOE FCL – 2Q09
� Install and operate the 26kV FCL in the electrical grid – 2Q09
� Initiate design of a Transmission class FCL – 1Q09
� Evaluate commercially available 2G wire for suitability in a saturated core
FCL design - 2Q09
61
Cooperative Entities
� California Energy Commission (CEC)
� Southern California Edison
� Consolidated Edison
� Seattle City Light
� Bonneville Power Authority
� Los Alamos National Labs (LANL)
� Oak Ridge National Labs (ORNL)
� Trade associations: NEETRAC
62
Thank You