Grid protectionProtecting the grid from geomagnetic storms
A geomagnetic storm disrupts the Earth’s magnetic field by producing geomagnetically induced currents (GICs) on the Earth’s surface, which can enter the power grid at transformer stations and move along power lines, disrupting normal operations. A geomagnetic storm would reach Earth between fourteen and ninety-six hours, leaving little time to safeguard critical infrastructure. U.S. regulators are drafting reliability standards and procedures to protect the U.S. power grid from such storms.
U.S. regulators are drafting reliability standards and procedures to protect the U.S. power grid from a geomagnetic storm. There is no agreement among industry experts about the damage the power grid would suffer as a result of a large geomagnetic storm, but regulators have taken a proactive approach by issuing Order 779 on May 2013. The order issued by the Federal Energy Regulatory Commission (FERC), instructs the North American Electric Reliability Corporation (NERC) to launch a two-stage planning process.
CNBC reports that in the first phase, NERC will develop reliability standards which require owners and operators of the electric transmission system to develop operational procedures to mitigate the effects of a geomagnetic storm. NERC has recently submitted a three-point operation plan to the FERC for approval. The operational plan calls for regional reliability coordinators to develop a geomagnetic storm operating plan and disseminate space weather forecasts to utilities and transmission operators. Transmission operators will also be required to develop operating plans which reflect how they will respond to an incoming geomagnetic storm.
In the second stage NERC will develop standards requiring transmission owners and operators to conduct frequent assessments of how a geomagnetic storm would affect their specific equipment. In FERC’s words, stage two will “require owners and operators to develop a plan so that instability, uncontrolled separation or cascading failures of the bulk power system, caused by damage to critical or vulnerable equipment … will not occur as a result of a (solar storm).”
FERC notes that transmission owners will not be allowed to rely solely on operating procedures. Rather, they must also develop strategies for protecting the grid “based on factors such as the age, condition, technical specifications or location of specific equipment.”
Such strategies could include “automatically blocking geomagnetically induced currents from entering the bulk power system, instituting new requirements for new equipment, inventory management, and isolating certain equipment that is not effective to retrofit.”
Industry is concerned about the additional costs these safety mandates would entail, especially in light of the fact that the damage to transformers is uncertain, but FERC has rejected the industry’s objections.
Geomagnetic storms can occur with little warning. The worst geomagnetic storms are the result of coronal mass ejections (CMEs) in which billions of tons of highly charged particles from the sun’s surface shoot into space toward the Earth and disrupt the Earth’s magnetic field. A geomagnetic storm would reach Earth between fourteen and ninety-six hours, leaving little time to safeguard critical infrastructure after a CME has been detected. NASA’s Advanced Composition Explorer (ACE) satellite, located a million miles from Earth, can give a 30-minutes first-warning on the severity of an incoming geomagnetic storm.
A geomagnetic storm disrupts the Earth’s magnetic field by producing geomagnetically induced currents (GICs) on the Earth’s surface, which can enter the power grid at transformer stations and move along power lines, disrupting normal operations. Wild fluctuations in voltage across power lines could cause power failure as relays try to isolate vulnerable equipment. High-voltage transformers could become overloaded and overheat, leading to permanent damage. Old high-voltage transformers nearing the end of their service lives are most vulnerable.
The power industry stores a limited supply of high-voltage transformers because of their limited availability. According to the general manager of U.S. based Pennsylvania Transformer, “I can only build 10 (high-voltage transformers) units a month.”
NERC says that should a solar storm occur, power could be restored to customers in a matter of hours, but the U.S. Department of Energy’s Oak Ridge National Laboratory says that a rare solar storm, such as those which hit the United States in 1859 and 1921, would damage as many as 300 high-voltage transformers. “Should a storm of similar magnitude (to 1859 or 1921) strike today, it could interrupt power to as many as 130 million people in the United States alone, requiring several years to recover,” Oak Ridge warned in a 2010 study.
