FERC proposes rulings on GMD, vegetation management

FERC has issued proposed rulings for standards that would both address the day-to-day operations of supplying electricity and prepare the industry for emerging issues.

Two notices issued by FERC on Oct. 18 propose the approval of a revised vegetation management standard and the requirement of new standards addressing the effects of a geomagnetic disturbance (GMD) on the bulk power system.

“These reliability orders address two distinctly different challenges and represent two different approaches to maintaining reliability,” Commissioner John Norris said in a statement. “Like a cyber attack, the potential size and duration of an outage that could result from a GMD demands that we take the precautions necessary to prevent, limit, or contain the potential impact.”

FERC’s notice of proposed rulemaking (NOPR) on GMDs would direct the North American Electric Reliability Corporation (NERC) to develop and submit new GMD standards in a two-stage process.

NERC would begin the process by filing standards requiring owners and operators to develop and implement operational procedures to mitigate GMD effects. NERC would then file standards that require grid owners and operators to conduct initial and continuing assessments of the potential impacts of GMDs.

Based on those assessments, owners and operators would implement strategies to protect the bulk power system, including automatic blocking of geomagnetically induced currents, instituting specification requirements for new equipment, inventory management, or isolating certain equipment that is not cost effective to retrofit.

A separate NOPR on vegetation management proposes approval of a revision submitted by NERC in December 2011 that would expand application of the standard to include lines below 200-kV that are part of an Interconnection Reliability Operating Limit or a Major Western Electricity Coordinating Council Transfer Path. The revision also would set a new minimum annual inspection requirement and incorporate new minimum clearance distances.

“The standard we propose to approve is one of the first results-based standards put forward by NERC,” Commissioner Cheryl LaFleur said in a statement. “Because the standard is judged by results, it proposes to give more flexibility to transmission owners about how to meet those results, as long as they are met. This is an important concept, and the successful implementation of this standard may be a model for further results-based standards.”

While the technical community has debated whether GMDs from solar events would cause the bulk electric system to break down or cause damage to high-voltage transformers and other key elements of the system due to inductive currents, LeFleur added, “any of these results is unacceptable, and is exactly the sort of cascading disturbance to the bulk power system that section 215 of the Federal Power Act requires us to address.”