NERC points to possible summer issues in Texas, southern California

The North American Electric Reliability Corp. said May 15 that the nation’s grid is in fairly good share for the 2013 summer peak demand season, there are isolated concerns about a lack of peaking capacity in Texas and a shut nuclear plant in southern California.

NERC on May 15 published two reports to help inform industry and policy makers on trends, challenges and recommendations for ensuring the reliability of the bulk power system. The 2013 State of Reliability provides an integrated view of reliability performance, and the 2013 Summer Reliability Assessment identifies common themes or challenges across North America for the upcoming summer.

“These assessments of performance and anticipated seasonal conditions are an integral part of delivering on NERC’s mission to ensure bulk system reliability for North America,” said Thomas Burgess, vice president and director of Reliability Assessment and Performance Analysis.

NERC’s 2013 Summer Reliability Assessment seeks to identify areas of concern regarding the reliability of the North American bulk power system and to make recommendations for necessary actions. The assessment identifies summer resource adequacy and operating reliability concerns, determines peak electricity demand and supply changes and highlights unique regional challenges.

“We expect the bulk power system will be able to meet the electricity demands this summer,” said John Moura, director of Reliability Assessment. “However, continued peak demand growth in Texas coupled with only a small amount of new resources made available this summer is causing resource adequacy projections to fall below targets. NERC will closely monitor the situation in ERCOT, as well as impacts from persisting drought conditions in the west.”

Key assessment report findings include:

Summer planning reserve margin below the NERC Reference Margin Level in Electric Reliability Council of Texas (ERCOT) – ERCOT’s Anticipated Reserve Margin is 12.88% for this summer, which is below NERC’s 13.75% target for the area. Insufficient reserves during peak hours could lead to increased risk of emergency operating conditions, including curtailment of interruptible load and even rotating outages of firm load. ERCOT and generation capacity owners have taken actions to enhance resource adequacy and the Public Utility Commission of Texas is working to tackle generation insufficiency for this summer, as well as long term.

Tight supply resources in southern California may lead to operational challenges – Because of the continued shutdown of the San Onofre Nuclear Generation Station, which began in late 2011, a prolonged and/or extreme heat wave could result in localized controlled load shedding in San Diego and Los Angeles Basin to maintain integrity of the system. Several system enhancements were completed or planned to be in-service by summer peak, which should relieve some operational issues and support system flexibility during conditions of stress.

Wind and solar capacity increase adds supply uncertainty – Solar and wind expected on-peak capacity is 2,928 MW and 11,753 MW respectively. An increase in wind and solar resources challenges operators with inherent swings in power output. Weather also plays an important role in determining wind and solar output; therefore, enhancing regional forecasting can provide more accurate generation projections.

Drought conditions west of the Mississippi River require enhanced plant, system monitoring – While no substantial operating impacts are projected, increasing drought conditions could give rise to localized changes. The National Oceanic and Atmospheric Administration predicts moderate to exceptional drought in 51 percent of continental United States, primarily in the Central, Midwestern and Western regions.

Additional assessment findings include:

  • Retirements and retrofits to meet environmental regulations of mostly coal-fired capacity are not anticipated to cause immediate reliability concerns.
  • Above average growth in peak demand projected in ERCOT and Western Electricity Coordinating Council (WECC).
  • Active hurricane season and increasing dependence on natural gas.

Efforts underway in southern California to shore up the system

Said the assessment report about Southern California Edison‘s San Onofre plant: “The 2,250 MW San Onofre Nuclear Generating Station (SONGS) in southern California has experienced premature wear in the steam tubes for both of the plant’s units, which have been shut down for repairs since late 2011. In addition to the power generated at the nuclear plant, voltage support for moving that power is an important factor for reliability and avoiding transmission problems in southern Orange County. With this plant unavailable, a prolonged or extreme heat wave, or unexpected resource outages, could result in localized controlled load shedding to maintain system integrity.”

From an operations perspective, the California Independent System Operator (CAISO) has expressed concerns of emerging hydro generation challenges, the report added. Seasonal preparations and non generation alternatives to mitigate load shed risk for multiple‐contingency events are being considered. Operating reserve margins in the southern portion of CAISO (SP26) appear sufficient to maintain reliability, albeit tight for an extreme demand case. Therefore, from a capacity perspective, sufficient resources are expected to be available to meet the summer peak, the report added.

To mitigate potential reliability concerns, several system enhancements have been completed or are planned to be in‐service by the summer peak season in southern California. These enhancements include converting Huntington Beach units 3 and 4 into synchronous condensers, installing capacitors (80 Mvar each at Santiago and Johanna; 160 Mvar at Viejo), the splitting of the Barre‐Ellis 220 kV circuits (from two to four lines), the addition of new capacity resources (about 1,900 MW), and significant refinements to load curtailment and demand response programs. These improvements should relieve some operational issues and help support system flexibility during periods of stress; however, long‐term solutions will likely be needed if SONGS remains out of service, the report added.

Reliability report outlines key developments

NERC’s State of Reliability report delivers analytical information from a number of reliability indicators on trends and reliability risks that can be used for project prioritization, process improvement and risk identification. This year’s report reflects continuing steady overall reliability performance, with some indicators of improving trends between 2008-2012. The key findings include:

Bulk power system reliability remains adequate – The number of bulk power system transmission-related events since 2008 resulting in loss of firm load decreased from an average of nine per year to two in 2012.

Risks from standards violations are decreasing – Of the more than 5,000 violations to date, only two percent involved serious reliability impact, while nearly 85% had minimal impact to reliability, and 13% had moderate impact. Violations of NERC non-CIP standards assessed with serious impact are trending lower – 10 in 2012 down from 39 in 2008.

Transmission availability performance is high – There have been no significant changes in the high transmission availability between 2008-2012. AC circuit availability is above 97% and transformer availability is above 96% between 2010-2012.

Frequency response is steady – The expected frequency response for each interconnection remains higher than the recommended obligation.

“The 2013 report advances NERC’s reliability risk-issue identification methods in a consistent and predictable manner,” said Jessica Bian, director of Performance Analysis. “These methods involve sophisticated data analyses that extend traditional approaches and consider a broader range of factors potentially affecting reliability that provide a sound basis for prioritizing insights and guidance based on risk significance.”

The State of Reliability report draws attention to two risk issues that contribute to disturbance events and automatic transmission outage severity: protection system misoperations and AC substation equipment failures.

A task force formed to prevent future misoperations, developed recommendations, including improved root cause and data collection processes. A technical group is being formed to better understand AC equipment failures, and provide risk-control solutions to improve performance.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.