NOTICE DATE:  August 15, 2007

NOTICE TYPE:  W-C081508-01 Operations

CLASSIFICATION: Public

SHORT DESCRIPTION:  Reserve Discount Factor changed for determining Responsive Reserve Service requirements

INTENDED AUDIENCE:  QSE Operations Personnel

DAY AFFECTED:  August 19, 2008

LONG DESCRIPTION:  The ROS approved an ERCOT proposal that will adjust the Reserve Discount Factor (RDF) such that additional Responsive Reserve purchases will not be necessary.

 

The ERCOT Ancillary Service Methodology links the amount of additional responsive reserves procured to the day-ahead forecast and the forecast RDF between 6 a.m. and 10 p.m..  For each hour when the RDF is projected to be above 2 percent, ERCOT will adjust the day-ahead responsive reserves upward by 100 MW per percentage point, not to exceed 500 MW.  The ROS approved the ERCOT proposal to reduce the RDF from 7% to 2% for temperatures greater than 95 degrees Fahrenheit and from 5% to 1% for temperatures in the range of 85 to 95 degrees Fahrenheit.  Temperatures less than 85 degrees will reduce the RDF from 4% to 1%.

 

Beginning August 18, 2008 ERCOT will make the changes to the real-time RDF and will not purchase additional RRS for Tuesday August 19, 2008.

Responsive Reserve Service obligation under this change will be reflected in the regularly scheduled RRS QSE obligation posted by 6 a.m. for Day Ahead.

 

ADDITIONAL INFORMATION:  The practice of discounting responsive reserves was implemented in December 2006, following an analysis of actual reserves available on April 17, 2006, when rotating outages were implemented to avoid a system blackout.  (Originally, a 7 percent discount was applied; in November 2007, it was changed to a variable discount based on weather zone temperatures.) 

CONTACT:  If you have any questions, please contact your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via e-mail at [log in to unmask].

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