Geomagnetic disturbances caused by continuous solar activity distort the Earth’s magnetic field in varying degrees and are able to impact the operation of the electrical grid.
For example, in one of the most serious cases in March 1989 a severe geomagnetic storm brought down Hydro Québec’s grid within 90 seconds when the magnetic field variations tripped circuit breakers on the company’s grid. Forced outages of electric power equipment in the northeastern United States are also among the impact of such space weather on the electric power industry.
While such events have a high impact, they are also of low frequency. They generally coincide with periods of solar maximum, which occur on an approximately 11-year cycle. The latest solar maximum occurred in 2013-14 and was one of the weakest on record. They are also able to be predicted with a moderate degree of success, according to a 2009 report from NASA, which also called for improved forecasting capability.
Plans to mitigate effects of geomagnetic disturbances
In May 2013, FERC directed the North American Electric Reliability Corporation (NERC) to develop and submit new geomagnetic disturbance standards through a two-stage process.
In the first stage, in June 2014 FERC approved a standard on the implementation of operating plans, procedures and processes to mitigate the effects of geomagnetic disturbances. The new rule, applicable to reliability coordinators and transmission operators within areas that include certain transformers with terminal voltage of more than 200kV, required these operators to develop and implement plans to coordinate operating procedures and to develop procedures to address geomagnetic disturbance events. The rule also requires reliability coordinators to disseminate space weather information.
Vulnerability assessment to geomagnetic disturbances
In the second stage NERC has proposed a standard setting requirements for transmission planners and owners to assess the vulnerability of their systems to a “benchmark ‘one-in-100-year’ geomagnetic disturbance event.”
Specifically, the standard would require entities to have system models needed to complete vulnerability assessments, to have criteria for acceptable steady state voltage performance during a benchmark event, and to complete a vulnerability assessment once every 60 calendar months. If the assessment indicates that a system does not meet the performance requirements, the entity would have to develop a corrective action plan addressing how the requirements will be met.
FERC’s Notice of Proposed Rulemaking is now open for comment for 60 days. FERC has indicated that it will accept the standard with some modifications. For example, FERC expresses concern over the definition of a benchmark geomagnetic disturbance event, given the limited historic geomagnetic data and because scientific understanding of such disturbances is still evolving.
FERC has also indicated it expects to request from NERC informational filings addressing specific geomagnetic disturbance-related research areas.
Strategy for space weather
In addition to the electric grid, space weather events can impact other industries and sectors including satellite and airline operations, communications networks and navigation systems.
In order to reduce vulnerability to space weather, the US National Science and Technology Council has released a draft National Space Weather Strategy proposing six goals:
• Establish benchmarks for space weather events
• Enhance response and recovery capabilities
• Improve protection and mitigation efforts
• Improve assessment, modeling, and prediction of impacts on critical infrastructure
• Improve space weather services through advancing understanding and forecasting
• Increase international cooperation.
Energy is identified along with communications systems as “uniquely critical” due to the enabling functions they provide across all critical infrastructure sectors.