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The power grid is subject to sharp fluctuations in times of solar flare storms. The next wave of storms will hit in 2000. The author, John G. Kappenman, is in charge of Transmission Power Engineering at Minnesota Power, Duluth, Minnesota
This article appeared in the May 1996 issue of IEEE POWER ENGINEERING REVIEW.
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For example, Solar Cycle 22 (the current 11-year sunspot cycle) which is now drawing to a close, produced not only above-average but historic geomagnetic storm activity. As a consequence, above-average impacts to system reliability occurred due to storms, with the most notable instance resulting in a large area blackout. Also, several well documented cases convincingly established that large, expensive transformers could be damaged by exposure to Geomagnetically Induced Currents (GIC) that are produced by storms. Further, statistical evidence is showing that transformers are failing at an above-average rate in areas of the United States that are particularly prone to geomagnetic disturbances, resulting in well-above-average replacement costs that could measure in total into hundreds of millions of dollars in costs to the industry. If that's not enough, experience teaches us that the odd numbered Solar Cycles (Cycle 23 in this case, which is in the process of initiating) have always been more severe than the even numbered cycle that they follow. . . .
Power System Reliability Threat
Threats to power system integrity are no longer just academic speculation with the events that unfolded during the Great Geomagnetic Storm of March 13, 1989. In fact, the entire Hydro Quebec system was plunged into a blackout triggered by GIC caused voltage collapse and equipment malfunction. The impact of this particular storm was simultaneously felt over the entire North American continent with most of Hydro Quebec’s neighboring systems in the US coming uncomfortably close to experiencing the same sort of voltage collapse/cascading outage scenario. . . .
Wide area blackouts are the nightmare scenario of our industry and geomagnetic storms that span large regions of the network impose a unique and previously unanticipated threat to interconnected system operation. . . .
GIC Caused Transformer Failures? ( or Fried Green Transformers)
During the same March 1989 storm, several incidents of transformer heating problems were reported as well. The most significant failure occurred at a GSU (generation step-up) transformer at a nuclear plant in New Jersey in which a 1,200 MVA, 500kV bank was damaged beyond repair. . . .
Direct long-term evidence of GIC-caused transformer problems does not exist, simply because utilities had not done any long-term monitoring of GIC exposure.
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