Day-Ahead Market (DAM) Submissions

1. Day-Ahead Market (DAM) Submissions NATF April 6, 2010 http://nodal.ercot.com 1

2. Agenda • Multi-hour blocks not supported for energy curves • Bid/offer submission efficiencies for purposes of DAM clearing http://nodal.ercot.com 2

3. Issue #1- Multi-hour blocks not supported for curves http://nodal.ercot.com 3

4. DAM submissions Multi-hour blocks for curve submissions • When you submit an Energy Only Offer or an Energy Bid, you have the choice of submitting using fixed, variable or curve quantity types. Curve type allows for the entry of up to 10 price/quantity pairs. Further, you can create a multi-hour block that will ensure that your bid/offer is awarded the same quantity for all hours in the time block. • It was identified that the system cannot handle multi-hour blocks for curve submissions. The functionality was disabled, so if a QSE submits a multi-hour block with a curve indicator, DAM will remove the multi-hour block prior to clearing and QSEs will receive awards of differing quantities for each hour http://nodal.ercot.com 4

5. DAM submissions Multi-hour blocks for curve submissions (cont’d) • Protocol section 4.4.9.5.1 and 4.4.9.6.1 only calls out multi-hour blocks for fixed and variable submissions 4.4.9.5.1(c): The fixed quantity block, variable quantity block, or curve indicator for the offer; (i) If a fixed quantity block, the single price (in $/MWh) and single quantity (in MW) for all hours offered in that block; (ii) If a variable quantity block, the single price (in $/MWh) and single “up to” quantity (in MW) contingent on the purchase of all hours offered in that block; and (iii) If a curve, a monotonically increasing energy offer curve for both price (in $/MWh) and quantity (in MW) with no more than ten price/quantity pairs; http://nodal.ercot.com 5

6. DAM submissions Multi-hour blocks for curve submissions (cont’d) • Documentation (Explanation of Market Submission Items) will be updated to explain the clearing behavior when a bid/offer is submitted as a curve type and multi-hour blocked. • No current plan to add a validation rule to prevent the initial submission http://nodal.ercot.com 6

7. Issue #2- Bid/Offer Submission Efficiencies http://nodal.ercot.com 7

8. DAM Submissions Bid/Offer submission efficiencies • ERCOT has identified efficiencies in Bid/Offer submissions with regard to formatting. This applies to all transactions that use a Bid ID or an Offer ID • Energy Only Offers • Energy Only Bids • PTP Obligation Bids • CRR Offers Bid/Offer IDs are used to submit multiple bids/offers for the same settlement point(s) for the same hour. • Preference is for QSEs to submit the same Bid/Offer ID for each hour in the submission, versus submitting a different Bid/Offer ID for every hour. The clearing engine treats the submission the exact same way, regardless of which way it is submitted. • However, if the same Bid/Offer ID is used for each, it is stored as one entry in a particular MMS table. If different Bid/Offers IDs are used for every hour, it is stored as 24 different entries into this table. http://nodal.ercot.com 8

9. DAM Submissions Bid/Offer submission efficiencies • This preference (for using the same Bid/Offer ID) is due to system performance, and if most QSEs use the preferred method, more bids and offers can be submitted before DAM sizing limits are exceeded • We ask that if you use web services for DAM submissions, please check your systems to see if they are in line with this preference. • For xml examples detailing this issue, please view the document titled ‘Preferred Format for DAM Submissions’ that is posted on the NATF agenda page along with this presentation at http://www.ercot.com/calendar/2010/04/20100406-NATF http://nodal.ercot.com 9