1. Southern Company Transmission
Geomagnetic Disturbances (GMD) Causes and Effect on the North American Grid
Warren Whitson
Southern Company Transmission
NERC GMD TF Member
IEEE Member
April 16, 2012

2. Sunspots
During solar minimum the Sun's magnetic field, like Earth's, resembles that of an iron bar magnet, with great closed loops near the equator and open field lines near the poles. We call the Sun's magnetic field the "Interplanetary Magnetic Field" or “IMF." The Sun's dipolar field is about as strong as a refrigerator magnet, or 50 gauss. Earth's magnetic field is 100 times weaker.
During the years around solar maximum (2000 and 2001 are good examples) spots pepper the face of the Sun. Sunspots are places where intense magnetic loops -- hundreds of times stronger than the ambient dipole field -- poke through the photosphere. Sunspot magnetic fields overwhelm the underlying dipole; as a result, the Sun's magnetic field near the surface of the star becomes tangled and complicated.

4. 11 year cycle
Entering more active phase
Max in May 2013
Increased media attention

5. Types of Space Weather Storms
Solar Flares: These are intense temporary releases of energy, which cause burst of radio and X-ray wavelengths, lasting from minutes to hours. They travel at the speed of light, but generally they do not cause impact to the electrical grid. They can result in Radio Blackouts which can affect critical systems like GPS.
Radiation Storms: Typically occur during a solar flare, they shower the earth, generally within 30 minutes of the flare, with solar particles, typically protons which penetrate the earth’s atmosphere. They are a threat for satellite and space operations, but typically do not affect the grid.
Geomagnetic Storms: These are caused by a Coronal Mass Ejection, which is a cloud of solar material and magnetic fields, which, if they contact the earth, creates a disruption in the earth’s magnetic field. Timing is usually one to four days after the solar flare. This is the condition which can affect our transmission grid.

6. Graphic Depiction of a Coronal Mass Ejection

7. Magnets and Electricity
Magnetic Fields
Electromagnets
Electric Generator
(Reverse input/output for motors)

8. How Does this Impact the Grid?
Ionized particles bombard the Earth
Earth’s magnetic field disrupted
Electric potential induced on earth’s surface
DC current (GIC) induced in neutral of transmission lines
Transformer saturation
Overheating -> damage (especially older equipment)
Produce harmonics
Increased reactive power requirements
SVCs, Caps, etc… tripped by protection
Potential for system collapse - blackouts

9. Power Transformer Saturation
GIC can increase exciting current 3x during saturation
leakage flux also increases dramatically, causing overheating
Produces harmonics
Increased Var (reactive power) demand
Distorted AC current on nearby line

10. Effects of GIC in an HV Transmission Network

11. The U.S. Grid High Voltage Grid
U.S. is split into three separate grids

12. Latitude and Orientation
Impact is greater at more northern latitudes
Magnetic field lines are closer together near the poles
Hence stronger GIC
Historically below 35th parallel considered safe
In 1989 storm GIC at Mississippi coast was equal to those in Hydro Quebec blackout
Orientation of storms vary
Direction of transmission lines determines GIC mag.

13. Percent Probability of Occurrence of Hourly Peak dB/dt greater than 300 nT/min

14. Transmission Line Susceptibility
Long high voltage lines are more susceptible
Potential difference is a function of distance
High voltage lines have low impedance

15. Major Historical Events
Sept “Super Storm”
Largest GMD event ever recorded
2x stronger than 1921 storm
May 1921
10x stronger than 1989 storm
Northern lights seen from Puerto Rico
“100 year storm” - debatable
March 1989
Significant grid impacts
Hydro Quebec blackout

16. Hydro Quebec Blackout - 1989
Hydro Quebec’s (TransE’nergie) electric transmission system collapsed in 92 seconds
Seven of seven SVC’s tripped within the first few seconds
At the same time reactive demand increased by 1600 MVAR
Long HV lines - generation far from load
The storm left six million people without service for nine hours or more
Several transformers failed (cause of failure is disputed)
A GSU transformer failed at a nuclear plant in the USA
Two large network transformers failed in the UK
Two additional transformers failed on the HQ system due to load rejection
NERC, in their post analysis, attributed over 200 significant anomalies across the continent to this one storm
Many capacitors tripped due to harmonics
Low voltages

17. Geomagnetic intensity – March 1989 Storm

18. Mitigation Methods GIC Reduction Device (GRD) Operational
Resistor or capacitor in transformer neutral or in series on line
Unproven technologies
Operational
Increase awareness
Increase import capabilities
Increase real & reactive reserves
Decrease loading on susceptible equipment
Robust spare equipment program
Specification of transformers with better GIC immunity
Shielding and hardening of our relay and control devices
Backup communication systems

19. NASA’s Solar Programs STP, STEREO, SOHO, MMS, Solar-B, TIMED, ACE etc…
Several satellites in various orbits
Provide images and video
Warning of earth directed CME a day or more ahead
Accurate projection minutes ahead
Magnitude
Polarity
Location

20. Location of NASA Satellites between Earth and Sun

21. Space Weather Prediction Center

22. Occurrence of Kp values
from 1932 to 1991
~1700 per cycle
~600 per cycle
~200 per cycle
~100 per cycle
~4 per cycle

24. FERC Activity Study by Storm Analysis Consultants (SAC)
Congressional EMP Commission
Worst-Case results:
100,000 MVARs of increased reactive demand
Widespread blackouts in eastern U.S.
350 transformers damaged or destroyed
$1-$2 Trillion in damage in 1st year
Up to 10 years for full recovery
Impacts shown at southern latitudes
Previously only at more northern latitudes
FERC becomes concerned about GMD
Prompting NERC to take action

25. Storm Analysis Consultants
Source: The Vulnerability of the US Electric Power Grid to Severe Space Weather Events and Future Outlook, John G. Kappenman, Metatech Corp.
Storm Analysis Consultants

26. Storm Analysis Consultants

27. Location of At-Risk Transformers
4800 nT/min at 45o (GIC > 90 Amps/phase)
Storm Analysis Consultants

28. The SHIELD Act In response to the EMP Commission Report
“To amend the Federal Power Act to protect the bulk-power system and electric infrastructure critical to the defense and well-being of the United States against natural and manmade electromagnetic pulse (‘‘EMP’’) threats and vulnerabilities.”
In response to the EMP Commission Report
60% casualty rate for ‘prolonged’ power outage
HR668 – Proposed by Rep. Franks : Arizona (Feb, 2011)
Secure High-voltage Infrastructure for Electricity from Lethal Damage Act
Different from Senate’s SHIELD Act (classified info)
Still waiting for vote
Mandates FERC to develop standards and enforce compliance

29. NERC Activity GMD Task Force formed - 2010
Industry Advisory issued on GMD – May 2011
Information only
No response required
Preliminary Report released – Spring 2012
Space weather prediction/detection
Mitigation options
Operational practices
FERC pressure for further action (Level 2 alert?)
Recommended actions

30. NERC GMD TF’s Proposed GMD Risk Mitigation Strategy
Components
Phased Approach

31. EPRI GIC Project Assumptions: Steps:
Maxwell’s equations instead of Earth Surface Potential (ESP)
DC model
500 kV lines + autos (for now)
100 year storm (~1921)
Steps:
Model GIC flows (DC amps)
VAR demand
Harmonic production
System protection (CT saturation, relays)
Blocking options and effectiveness

32. The EPRI SUNBURST Project
Near Real -
Time
SUNBURST Web Site
Geomagnetic
Monitoring
Database
SUNBURST
Web
Server
Internet
Your Grid
Xfmr 1 DC
View GIC Data at any location: •
System Operations
Engineering
Power Plants
Substations
Corporate Office
Power
System
Data
NOAA
Solar Wind Data
2000
International
Utility Sites
Data Sent to
Electric
Research
Web Pages
Utility
Site
Utility Site
SUNBURST Center
Electric Research
EPRI
SUNBURST is an EPRI Collaborative R&D project
SUNBURST’s objectives are:
Monitor actual transformer neutral currents at SUNBURST member sites
Provides a local & global view of GIC impacts in near real-time
Conducts critical research on behalf of the project members

33. Summary Increased focus on GMD in power industry
Congressional EMP Commission
Storm Analysis Consultants’ study
Solar storm/sunspot cycle
FERC is pushing for action
NERC alert and report has been issued
Still vetting SAC study
Developing study realistic scenarios/assumptions
Developing modeling expertise/capabilities
Determining potential for damage to transformers
EPRI is heavily involved
There is still much uncertainty and little consensus, but we are making great progress

34. Acknowledgements and Recommended Reading
Some of the material in this presentation was obtained from the following sources:
NERC, Effects of Geomagnetic Disturbances on the Bulk Power System February 2012
NERC, High Impact, Low-Frequency Event Risk to the North American Bulk Power System dated June 2010.
NERC, Report on the March 13, 1989 Disturbance
US Department of Defense, Low latitude auroras; The Magnetic Storm of May 1921
EPRI, Approaches for Minimizing Risks to Power System Infrastructure
EPRI – Presentation titled “Research into GIC’s”
Wikipedia, articles on GIC, GMD, Electromagnetic Pulses, and the K Index
NOAA Space Weather Prediction Center (
Space Weather.com - Various information and references
FERC EMP-GIC Metatech Reports
Alton Comans, Chief Engineer, Southern Company Services

35. Questions?