Protecting the World’s Power Grid from a Catastrophic GMD Event

| Gary Hoffman, David Law

It all began on April 1, 2009 at the Doble Clients Conference in Boston, Massachusetts, with a curious visit by George Wood of Dominion Virginia Power Company (DVP). The company where I am President and CEO, Advanced Power Technologies, manufactures transformer monitoring equipment sold to electric utilities. I was discussing a new product we had under development that would do some interesting things including measurement of AC current harmonics on power transformers. At the time I was aware of an issue with more reliably start cooling on a certain type of older but very important power transformers. This resonated with George who at the time was the manager of Electric Transmission Substation Operation for DVP. As we talked, George brought to my attention another problem DVP and other utilities were facing: detection of the effect of Geomagnetically Induced Currents (GIC) on their fleet of important power transformers. He indicated that GIC may cause an abundance of harmonics which a device like ours could detect and thought that had value.

We continued to talk and in the ensuing months met in Richmond, Virginia to discuss the issue with some of their engineers tasked to look at the vulnerability of the DVP transmission system when GIC is present due to a significant Geomagnetic Disturbance (GMD) from our Sun. A GMD occurs from sun spot activity. Sun spots are darker and hence cooler areas of the Sun. Sun spots occur when the sun’s magnetic field becomes non-uniform. This allows solar flares to occur that throw out Hydrogen and Helium ions into Space. This phenomenon is known as a Coronal Mass Ejection or CME. It was clear from our discussion that there was no consensus of how to detect if an event may cause a problem. In the past, CME’s have caused problems in the Power Grids of North America (1989) and Europe (2003). These events caused blackouts and great concern about the Grid’s vulnerability. Further the most significant GMD event known as the Carrington Event after a British astronomer studying sun spots, occurred in 1869 when people saw the Aurora Borealis in the Caribbean and Hawaii and telegraph systems operated without their batteries.  The conclusion of our discussion was that detection was important and certain harmonics may be important to detection but what were they?

We introduced our new product called ECLIPSE, coincidently not named for the Sun, with harmonic detection and we sold a few systems for the purpose of detecting GMD events. While visiting one of our customers who decided to try it, I observed the presence of the very harmonics being touted as indicative of a GMD event. However, that day the readings from the various magnetometers that the National Oceanic and Atmospheric Administration (NOAA), who was responsible for reporting space weather, were very low. As it turned out the power transformer was feeding a server farm used by one of the larger Internet retailers. These server farms have large UPS battery backup systems that are notorious for generating copious amounts of harmonics. That was a seminal moment as the method chosen would never be reliable and there had to be a better way.

It was now the winter of 2012 and I gathered my Engineers for another brainstorming session on the topic of GIC detection. As we reviewed what we knew, we started to examine some IEEE Transaction Papers, of which there were many on the subject. We decided to look only at those that reported results from actual physical events. There it was hiding in plain sight! The transformer core could be seen to saturate when the GIC was high enough and the harmonics associated with every one of these events had a specific pattern: The even harmonics were greater than the odd harmonics! We next formulated a detection algorithm and built a prototype to test our idea. Commensurate with that activity we began to work on a provisional patent filing in April 2012 to protect our idea. Satisfied from our tests that our idea would work, we proceeded to work with our Patent Counsel to file a U.S. Patent Office (USPTO). On January 8, 2013 we filed our patent with the USPTO and on April 28, 2015 the US Patent Office granted Patent 9,018,962. This was good timing because the United States Federal Energy Regulatory Commission or FERC, issued Ruling 779 calling for Electric Utilities interconnected in North America had to develop operating procedures, a vulnerability assessment and mitigation strategy in event of a significant GMD.

The IEEE has many Societies and Technical Committees that are involved in Standards development through the IEEE Standards Association. Many Standards are created by these Societies and Technical Committees that impact what we Engineers do on a daily basis. As a Member of the IEEE Power and Energy Society’s Transformer Committee, we took the initiative to answer the need for a comprehensive guide to answer the call to satisfy Grid operators across the World. In March 2014, a Project Authorization Request (PAR) was approved by the IEEE Standards Association for a new guide PC57.163 titled: Guide for Establishing Power Transformer Capability while under Geomagnetic Disturbances. In the Guide, the Working Group participants felt it important to cover the monitoring of GIC as well as harmonics. In an effort to share our technology, my Company filed an accepted Letter of Assurance (LOA) in May 2014 for the use of our technology for a reasonable and non-discriminatory (RAND) license. This enabled implementers of the Guide to have a reliable method to alert Grid operators when a vulnerable power transformer may have an issue.

I am pleased to report that in September 2015, IEEE Std™ C57.163 was approved by the IEEE Standards Association for publication making this unique technology available to improve the Grid’s reliability should a significant GMD event occur.


Hoffman GaryGary Hoffman

Founder, President and CEO, Advanced Power Technologies

Gary Hoffman is Founder, President and CEO of Advanced Power Technologies where he has been for the last 15 years. Previous to starting APT, Gary was General Manager of ALSTOM T&D Protection and Control Division in the United States where he spent three years. Prior to ALSTOM, he was with RFL Electronics where he held various executive positions including Senior Vice President of Sales and Marketing, Vice President of Operations, and Vice President of Engineering over an 8-year period. Mr. Hoffman holds 10 U.S. and Foreign Patents and is a Fellow Grade Member of IEEE, Member of the IEEE Transformers Committee, and Chair of Working Groups C57.12.10 and C57.116 as well as Vice Chair of PC57.163. He is also a member of the IEEE SA Standards Board, member AudCom and ICCom past member of RevCom ProCom, and PatCom. He is the author of Chapter 24 titled On-Line Monitoring of Liquid-Immersed Power Transformers. This book is edited by James H. Harlow. Mr. Hoffman’s chapter deals with economic justification for on-line monitoring and covers the various techniques used to perform on-line monitoring major power transformer components including Power Transformer Core, Coil, and insulation systems; Power Transformer bushings; Load Tap Changers; Instrument Transformers. He is also a contributor to EPRI’s The Copper Book, Chapter 9–Monitoring and Diagnostics. He holds a B.S. Engineering and M.S. Electrical Engineering from the State University of New York at Stony Brook.