To the experts, it’s a Geomagnetic Disturbance, or GMD. To most of us, it’s a solar flare.
Whatever its name, it can fry a large electricity system, burn out controls, and black out square miles in seconds, like the massive flare that brought down the grid in Canada’s Quebec province for nine hours in 1989.

Now, the power industry and regulators responsible for electric reliability are trying to figure out how to stop it, or at least minimize the potential damage.

A core problem is trying to figure just how bad a solar flare can get, and how often a big eruption might occur, experts told a joint meeting of the Federal Energy Regulatory Commission (FERC) and the Nuclear Regulatory Commission (NRC) June 15.

When engineers want to design nuclear power plants that will withstand historic earthquakes and floods, they have thousands of years of geologic data to use in calculating how big a threat a plant might face.

When they want to harden plants and the US electric grid against solar storms, their information dates back to 1859, when telegraph messages were first disrupted.

GMD has become an increasing concern as the number of extra-high voltage transformers, direct-current high-capacity long-distance lines, and digital controls has increased. Those are more vulnerable to GMD-induced currents.

No Two Events Will be Identical

Regis Binder of FERC’s Office of Electric Reliability said clouds of the sun’s ejected coronal material take 2-3 days to get to earth, but their effect depends significantly on the cloud’s polarity and where it hits the earth’s atmosphere – no two events will be identical.

Depending on polarity, the earth’s magnetic field may push back the cloud, or it may channel the energy along geomagnetic lines.

That polarity can be detected now only moments before impact, and only by a single satellite, which is now operating beyond its design lifetime. Its replacement isn’t scheduled to be launched till 2014 – a result of budget cuts, noted NRC Commissioner Kristine Svinicki.

In the last decade, a range of US agencies including the Federal Emergency Management Agency, the Department of Homeland Security, the National Oceanic & Atmospheric Administration, the Department of Energy’s Oak Ridge National Laboratory, FERC and NRC, and the North American Electric Reliability Council (NERC) have been assessing ways to minimize damage from these hard-to-predict events.

NERC Vice President Mark Lauby said a GMD Task Force has looked at scenarios and concluded that a “voltage collapse” would be the most likely outcome of a severe GMD, which would mean a blackout and probably equipment like system transformers damaged or destroyed.

Binder said equipment designed to stop the induced current flows can have unwanted side effects on the power system, so more work is needed to improve system survivability.

Lauby said NERC has launched a spare equipment database so that replacement parts can be located quickly at need.

Dan Dorman, Deputy Director in NRC’s Office of Nuclear Reactor Regulation, said measures US nuclear plants took to decrease vulnerability after the 9/11 attacks included stationing spare emergency equipment around plants, which could also help with GMDs.

In addition, he said, post-Fukushima measures include regional emergency equipment centers, adding more backup for GMDs, and all nuclear stations have backup diesel generators for emergency power supply.