***** EXTERNAL email. Please be cautious and evaluate before you click on links, open attachments, or provide credentials. ***** NOTICE DATE: December 29, 2017 NOTICE TYPE: W-A122917-01 Operations SHORT DESCRIPTION: Change to maximum Shadow Prices for constraints previously determined as irresolvable by SCED INTENDED AUDIENCE: ERCOT Market Participants DAY AFFECTED: January 1, 2018 and January 30, 2018 LONG DESCRIPTION: Section 3.6.2 of ERCOT's Business Practice, Setting the Shadow Price Caps and Power Balance Penalties in Security Constrained Economic Dispatch, requires ERCOT to review annually each constraint previously determined irresolvable by Security-Constrained Economic Dispatch (SCED), determine if the constraint has become SCED resolvable, and re-determine the maximum Shadow Price for constraints that continue to be irresolvable by SCED. Effective January 1, 2018, the following changes in maximum Shadow Prices will be made to the set of constraints that remain consistently irresolvable by SCED: Contingency Name Constraint Name From Station / kV Description Current Maximum Shadow Price ($/MWh) Maximum Shadow Price Effective 1/1/18 ($/MWh) BASE CASE VALIMP N/A Valley Import Base Case 2,000.00 2,000.00 SBAKHL48 6596__F HLTSW / 69 Loss of Bakke Tap to Unocal Parker Bakke 138 kV line overloads the 69 kV line from Emma Tap to Holt Switch 2,000.00 2,000.00 SWCSBOO8 BARL_FTSW1_1 FTSW / 69 Loss of the 138 kV line from Fort Stockton Plant to Barilla and Solstice overloading the 69 kV line from Barilla to Fort Stockton Switch 2,000.00 2,800.00 Additionally, effective January 30, 2018, the following constraints will no longer be considered irresolvable by SCED: Contingency Name Constraint Name From Station / kV Description SMCEABS8 ABNW_ELYT1_1 ABNW / 69 Loss of the 138 kV lines from Eskota Switch to McElmurray Tap Switchyard to Potter LCRA to Abilene South and Potter LCRA to Moore_Taylor Electric Coop overloads the 69 kV line from Abilene Northwest to Ely Rea Tap XSA2N89 SACH_69T1 SACH / 138 Loss of the San Angelo North 138/69 kV Auto transformer overloading the San Angelo College Hills 138/69 kV Auto transformer Section 3.6 of the Business Practice document requires a 30-day notice before the Shadow Price caps for SCED resolvable constraints are reset to their default values. Accordingly, the identified constraints will have their Shadow Price caps reset to their default Shadow Price cap values on January 30, 2018. Per Section 3.6.3 of the Business Practice document, the net margin values for constraints that remain irresolvable by SCED will be reset to zero on January 1, 2018. ADDITIONAL INFORMATION: The ERCOT Business Practice, Setting the Shadow Price Caps and Power Balance Penalties in Security Constrained Economic Dispatch, may be found on the Other Binding Documents List<http://www.ercot.com/mktrules/obd/obdlist> page of the ERCOT website. 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 email at [log in to unmask]<mailto:[log in to unmask]>. If you are receiving email from an ERCOT distribution list that you no longer wish to receive, please follow this link in order to unsubscribe from this list: http://lists.ercot.com. sa