power transmission transformers: saturation compensation
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POWER TRANSFORMERS:Saturation Compensation Modeling,
Simulation, and Experiments
John Thomas, Dr. David CopeEngineering Matters, Inc.
375 Elliot Street, Suite 130KNewton, MA 02464
www.engineeringmatters.com
14 October 2003
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Engineering Matters®
Short Form Resume
• Incorporated 1998• Woman-Owned Small Business• Won several Phase I and Phase II SBIRs• Electromechanical Focus
– Specialty motors and actuators, robotics, electromagnetic signature control and analysis
• Direct drive force feedback joysticks– Several patents received– Three high-performance versions available
• Ansoft user since 1984.
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Engineering Matters®
Design & Analysis Expertise
• Electromagnetics– Motors– Actuators– Sensors
• Electrical design– Power
– Analog and digital design
• Systems integration
• Mechanical design– Prototype– Design for
Manufacturing
• Software design– Firmware– GUI/API– Computer interfacing
• Control design.
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Power Transformer Saturation Progression
• Large scale common mode transformer currents, through a series of physical interactions, cause many deleterious effects. In some notable cases, these effects have led to total system collapse.
SMD
ESP
EMP
GICσ
Harmonics
B
H
VAR
HEATSMD = Solar Magnetic DisturbanceEMP = Electromagnetic PulseESD = Earth Surface PotentialGIC = Ground-Induced CurrentsVAR = Volts-Amps Reactive
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Reasons for interest in transformer saturation
• Transformer DC current causes half-cycle saturation, generation of harmonics, over-heating, increased audible noise, and mechanical stress.
• Results in decreased transformer life.
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Ground-Induced Currents (GIC) Two Causes:
• Solar Coronal Mass Ejections (CME) affect utility operations– Generates an Earth-surface
potential (1-10 V/km)– Drives a quasi-DC ground
current (10-100A DC)– Duration 2-4 hours.
• HEMP effects are more intense than CME effects– 10X voltage (10-100 V/km)– 10X current (~1000A DC)– 10-15 minutes/burst.
Image credit: NASA
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I
I/3 I/3
I/3
I/3 I/3
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Solar Magnetic Disturbances
• Solar magnetic disturbances (SMD) emit coronal mass ejections (CME) that interact with the earth’s magnetic field.
Image credit: NASA
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SMDs follow the 11 Year Sunspot Cycle
Measurementperiod
March 2003
Image credit: Meteorological Satellite Applications Branch, Air Force Weather Agency.
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Ansoft Maxwell® & Simplorer®
Modeling
• Three cases: (1) No GIC (before), (2) GIC (during), (3) GIC with compensation (after)
• Maxwell 2D nonlinear Model
• Simplorer Model– Block diagram &
circuit simulation– Post processing
analysis.
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Simplorer Block Diagram Functionality of three circuits
(PLL, time delay switch, op-amps)
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Simplorer Results:Post-processing FFT
Before GIC I2n~0
During GIC, large I2n
After GIC with Compensation I2n~0
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Maxwell 2D Results:Transformer |B| plots
Before GIC During GIC
Compensation
After GIC with
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Sub-scale Mock-up Demo Unit
• Sub-scale demonstration unit built & tested
• Experimental measurements compared with simulation results
GeneratorGSU XFMR
Step
-dow
nXF
MR
Load
CompensationCircuits
TransmissionLines
GICInjection
Filter
Filter
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Sub-scale Unit Measurements:Primary currents for three cases
Before GIC
During GIC
After GIC with Compensation
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Transformer Saturation Compensation Summary
• Natural & man-made events can cause transformer saturation which threatens power electric system stability and reliability
• Regained transformer stability by automated measurement and compensation
• Achieved very good comparison between simulations and experiments
• Future work will extend SMPS capabilities to higher power and voltage. More modeling and simulation are needed.
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Additional Projects of Interest (designed with Maxwell® 3D)
• Force Feedback Joystick (Direct drive, wide bandwidth, very rugged)
• MEMS OXC actuator
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Robotic Design and System Integration—Power Electronics, Vehicle design, Test Plan; RC, Motor
and Battery selection
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Acknowledgements
The GIC-compensation project was developed with funding from the United States Army Space & Missile Defense Command Contract numbers DASG60-01-C-0017 and DASG60-02-C-0066.
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Unconventional Alternative Power Applications
• Geothermal• Wave-action• Human-effort
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References
• Introduction to Geomagnetic Fields, Wallace Campbell, Cambridge University Press, NY, 1997.
• “Geomagnetic Storms and Their Impact on Power System,”Kappenman, John, G., IEEE Power Engineering Review, May 1996, p. 5.
• “Comparison of SS-GIC and MHD-EMP-GIC effects on power systems,” Meliopoulos, A.P.S.; Glytsis, E.N.; Cokkinides, G.J.; Rabinowitz, M. Georgia Inst. of Technol., Atlanta, GA, USA Power Delivery, IEEE Transactions on, Pages: 194-207 Jan. 1994 Vol. 9 Issue: 1 ISSN: 0885-8977.
• "Geomagnetically induced Currents during Magnetic Storms", R. Pirjola, Plasma Science, IEEE Transaction on, Vol. 28, No. 6, Dec. 2000, p. 1867.
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Significant Power System Outages (GIC & Other)
• GIC Storms: – February 1986, March
1989, March 1991, November 1991 and May 1992.
• GIC-Utility Events (place, people affected, duration): – North America: April 1940,
Sept. 1989, March 1991, Oct 1991
– Quebec March 1989, 6M, 9 hr. massive outage
• General Outages (place, people affected, duration):– US August 2003, 50M, 16-
20 hr. – London August 2003,
1.5M, 1 hr.– Denmark & Sweden
September 2003, 5M, 4 hr.– Italy September 2003, 57M,
9 hr.