LONDON, June 26: Power grids across North America and Europe have been on high alert all week as two massive solar storms have battered Earth, threatening to disrupt electricity supplies to millions of homes and businesses.
On Monday, PJM Interconnection, which coordinates power to 61 million people across 13 U.S. states and the District of Columbia, alerted generators and transmission companies as the first storm was upgraded from "strong" to "severe" by the U.S. government's Space Weather Prediction Center (SWPC) in Boulder, Colorado.
Controllers across the United States and Canada have been issuing similar warnings and preparing to stabilize their grids as unusually strong electromagnetic radiation emitted from the sun interacts with the Earth's own magnetic field and induces freak currents across the electricity transmission network.
A second storm is set to peak around 23:00 GMT on Wednesday, when highly charged particles which erupted from the surface of the Sun on Monday are forecast to reach Earth, according to the SWPC.
Grid controllers aim to prevent a repeat of the events of the night of March 13-14, 1989, when a geomagnetic storm induced severe currents on high voltage power lines near the U.S.-Canadian border and created a cascading failure which knocked out the entire Hydro-Quebec power grid in just 92 seconds.
Relays automatically disconnected transmission lines and generation units to protect the equipment from serious damage and power was restored to 83 per cent of affected customers within nine hours of the system's collapse.
But two large generator step-up transformers were damaged by excessive voltage in the 1989 storm. The threat to large high-voltage transformers worries industry executives and regulators because networks carry only a limited stock of spares and it could take months to manufacture, deliver and install replacements.
Geomagnetic disturbances are listed alongside cyber and physical attacks, pandemics and the electromagnetic pulse from the high-altitude detonation of a large nuclear weapon as high impact low frequency risks to the power network by the North American Electric Reliability Corporation.
Damage from the 1989 solar storm was largely confined to the Hydro Quebec network but bigger storms in 1921 and 1859 caused extensive damage to telegraph networks across the United States and Europe.     ?Reuters