On September 30, 2014, the North American Electric Reliability Corporation (“NERC”) published an analysis of the impacts of the 2013-2014 Polar Vortex on generator performance in the Eastern and Texas Interconnections, and made recommendations as to how to improve performance during future extreme cold weather events.
Among its key findings, NERC linked the unavailability of gas-fired generation during the Polar Vortex to curtailment or interruption of fuel supply. As natural gas is widely used outside of the electric power sector, the demand from other sectors—in particular residential heating demand during extreme cold weather events—can significantly affect the ability of pipeline operators and suppliers to deliver natural gas to generators. NERC also identified the inability of many generation facilities to withstand the extreme cold brought on by the Polar Vortex as a key vulnerability. Of the approximately 19,500 MW of capacity lost due to the cold weather conditions of this past winter, over 17,700 MW was due to frozen equipment. NERC found that many outages, including a number of those in the southeastern United States, were the result of temperatures that fell below the plant’s design basis for cold weather. NERC also found that during the extreme weather, System Operators used load reduction techniques like voltage reduction, interruptible loads, and demand-side management to maintain reliability, and made effective use of emergency procedures.
NERC listed the following among its key recommendations for improving generator performance ahead of and during future cold weather events:
- Review natural gas supply and transportation issues and work with gas suppliers, markets, and regulators to develop appropriate actions.
- Review and update power plant weatherization programs, including procedures and staff training.
- Continue or consider implementing a program for winter preparation site reviews at generation facilities.
- Review internal processes to ensure they account for the ability to secure necessary waivers of environmental and/or fuel restrictions.
- Continue to improve operational awareness of the fuel status and pipeline system conditions for all generators.
- Include in winter assessments reasonable losses of gas-fired generation and considerations of oil burn rates relative to oil replenishment rates to determine fuel needs for continuous operation.
- Ensure that on-site fuel and fuel ordered for winter is adequately protected from the effects of cold weather.
- Consider (where appropriate) the temperature design basis for generation plants to determine if improvements are needed for the plants to withstand lower winter temperatures without compromising their ability to withstand summer temperatures.
- Review the basis for reporting forced and planned outages to ensure appropriate data for unit outages and de-ratings.
NERC conducted the analysis using data from the Generator Availability Data System (“GADS”), first introduced by NERC in 1982. GADS data is used to calculate generator performance statistics, including information on forced outages, maintenance outages, planned outages, and derates. On August 4, 2011, the NERC Board of Trustees approved mandatory reporting of generator data to GADS for conventional generating units (excluding wind and solar), pursuant to Section 1600 of the NERC Rules of Procedure. Presently, conventional generating units with a nameplate capacity of 20 MW or greater are required to report; generating units less than 20 MW are encouraged to report unit information on a voluntary basis. GADS data is collected from all entities registered for the “Generator Owner” function on the NERC Compliance Registry.
A copy of NERC’s analysis may be found here.