Hatteras Island power outage and response

North Carolina's Hatteras Island experienced a power outage last week when construction activity damaged two underground transmission cables serving the island.  While the damage is repaired, residents face mandatory power conservation rules and visitors have been evacuated.

Hatteras Island is a barrier island located in North Carolina's Outer Banks.  While the island is relatively far offshore, it is connected to the northern Outer Banks islands by the Bonner Bridge.  Hatteras Island's roughly 4,000 residents and tens of thousands more seasonal visitors are supplied electricity by Cape Hatteras Electric Cooperative, a member-owned, not-for-profit electric distribution cooperative.

According to the cooperative, on July 27 a contractor building a replacement for the Bonner Bridge "accidentally drove a steel casing through the cooperative’s transmission cables" at the south side of the bridge.  The cooperative says it is taking steps toward both temporary and permanent solutions. For now, it is using a permanent diesel generator in the village of Buxton as well as temporary backup diesels to provide power to the island and is "working to expand the temporary generation service on Hatteras Island in order to accommodate a staged reentry of visitors." Meanwhile, the cooperative is working to splice the damaged underground cable and to build a new overhead transmission line, so permanent transmission service can be restored.

Calling the incident an "unprecedented complete loss of power delivery to Hatteras Island," Dare County issued a mandatory evacuation order for all visitors to Hatteras Island effective July 29, citing "life safety issues from the loss of reliable electrical power on Hatteras Island and growing uncertainty as to when repairs to the main transmission line will be completed to enable restoration of full power to the island."  Estimates suggested over 10,000 visitors have been kept off Hatteras Island as a result of the evacuation order, with proper credentials required for reentry.

According to the county's website, a complete repair might take from one to two weeks.  The county notes that the on-island diesel generators "will only be able to run if load is at minimal levels and everyone is conserving." The county cites mandatory power and water conservation measures in effect, including a requirement to disconnect system circuit breakers for air conditioning systems and hot tub heaters.

FERC proposes geomagnetic disturbance reliability standard

Is the U.S. electric grid ready for solar storms and other geomagnetic disturbances?  Today the Federal Energy Regulatory Commission proposed approving a new reliability standard for the grid to address its vulnerability to these hazards.

A utility substation near Treasureton in southeast Idaho.

Periodic activity on the Sun's surface sends powerful waves of energetic particles toward the Earth.  These solar events can distort the Earth's magnetic field, affecting the flow of electricity on Earth.  While serious geomagnetic disturbances are expected to be infrequent, they can cause blackouts and damage key utility infrastructure.

The Federal Energy Regulatory Commission has jurisdiction over the reliability of the U.S.'s bulk electric power system.  To this end, it has designated the North American Electric Reliability Corporation (NERC) as the nation's electric reliability organization.  In May 2013, FERC directed NERC to develop and submit new standards for protecting the grid against geomagnetic disturbances (Order No. 779). 

FERC and NERC have proceeded in a two-stage process.  First, in June 2014 FERC approved a standard on implementation of operating plans, procedures and processes to mitigate effects of geomagnetic disturbances (Order No. 797).

Reserved for the second stage were further requirements that transmission planners and owners assess the vulnerability of their systems to a theoretical benchmark event.  NERC subsequently proposed such a standard, calling for an evaluation of what would happen in a “one-in-100-year” benchmark event.

In a Notice of Proposed Rulemaking issued today, the FERC proposes to largely adopt NERC’s proposed second-stage standard.  The standard would require covered 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.

The proposed rulemaking would direct NERC to further modify its standard to require that the study and benchmarking of geomagnetic disturbance events is based on a more complete set of data and a reasonable scientific and engineering approach.

Comments on today’s Notice of Proposed Rulemaking are due 60 days after its publication in the Federal Register.

Geomagnetic disturbances, and their impacts to the grid, are a hot topic in energy regulation at the present. States are considering laws regulating utility readiness for and response to geomagnetic disturbances; for example, next week the Maine Legislature’s Joint Standing Committee on Energy, Utilities, and Technology will consider LD 1363, An Act To Secure the Maine Electrical Grid from Long-term Blackouts.