Power blackouts a risk associated with solar flares

Solar flares may appear in the media as “death rays” from the sun, but thus far in Canada, they seem to have caused no worse than a nine-hour power blackout in Quebec in 1989.Power blackouts are definitely a risk associated with solar flares, says William Bartley, assistant vice president and chief electrical engineer at Hartford Steam Boiler and Inspection Service. He was speaking at the 38th Annual Engineering Insurance Conference (AEIC) in Toronto on Oct. 13. But the risks should not be overblown, he added. Bartley’s presentation noted very large solar flares do have the potential to affect Earth’s geomagnetic field to a small degree. If you change the magnetic field, you create a voltage charge, Bartley said. That voltage charge is somewhat like a DC-type current. The Earth’s “resistivity” — a measure of how strongly a material opposes the flow of an electrical current — promotes the flow of this DC-like electrical current through power transformers and into transmission lines. The geomagnetic current charge fluctuates much more slowly than the typical charge in the transmission lines, causing “harmonics” in the transmission lines, basically a distortion of the normal electrical waves provided by the utility.Harmonics can “trip” a transmitter, much like a tripped circuit breaker shuts off and stops the flow of electricity through an electrical circuit. Bartley emphasized to the underwriters attending the conference that when an electrical system “trips,” this is not the same as physically damaging the system or causing it to fail. A “trip” could, however, cause a power blackout until the system is restored. For example, a solar flare was responsible for the Hydro Quebec blackout in 1989, when power service was interrupted for nine hours, Bartley noted.In answer to a question about mitigating solar flare risk, Bartley noted that hydro companies in Quebec and elsewhere are either considering or already installing devices to minimize the risks of solar flares. Quebec, for example, has installed “neutral blocking circuits,” which effectively block DC-like currents created by solar flares from entering the transmission lines. This essentially prevents harmonics, which can cause the trips and resultant power blackouts.