CSC/CRE Technical Review 6 October 2008

2 Outline  Review the process used in calculating Power Transfer Distribution Factors (PTDFs).  Information posted at:  CRE recommendations distributed on October 3 rd.

3 6 October 2008 PTDF vs. GSF  Power Transfer Distribution Factors (PTDFs) represent the percent of power transfer that flows on a transmission facility. PTDFs are used to estimate the change in flows that occur from a particular transfer and identifying which elements are impacted by the transfer.  Generator Shift Factors (GSFs) represent the change in flow on an element as a result of increasing generation at a node. GSFs are more useful in identifying the generator pairs that can impact a specific element.  Both PTDF and GSFs can be calculated using similar assumptions.  Source:

4 6 October 2008 PTDF process For each of the CSC Scenarios 3b, 3i, and 3h -  ERCOT coordinated Market Participant resources to assist in the calculation of PTDFs for each scenario  PowerWorld and Excel were used as the tools to calculate PTDFs for base case and contingencies of CSCs and CREs.  For the Base Case and each pair of contingency-monitored elements, the 3 plants with highest of GSFs for both directions were identified to review whether local solutions were feasible.

5 6 October 2008 PTDF Calculation Assumptions  Oklaunion movable and located in the West zone under Scenario 3i and 3b but not movable and located in the North zone under Scenario 3h.  Pmax available to resolve constraint for all unit movable units in each zone

6 6 October 2008 ERCOT’s CRE recommendations  ERCOT based it’s CRE recommendations on the results generated by the test outlined in Protocols Section  ERCOT is also permitted by the Protocols to select CREs that can provide improved operational control.  In determining whether a CRE provides improved operational control ERCOT reviewed the PTDF results and the location of the CRE.

7 6 October 2008 Who’s on first? 1)This column states whether the CRE was a 2008 CRE. 2)Explains the criteria used for recommending the line as a CRE; if a CRE only passed for a specific scenario, the scenario is provided in parenthesis. 3)Denotes which CSC scenario a particular CRE is recommended for; “x” marks the spot

8 6 October 2008 Average Weighted Shift Factor Scenario 3b AWSF Table ZoneW-NS-NN-SN-HN-W North South West Houston Scenario 3h & i AWSF Table ZoneW-NS-NN-SN-HN-W North South West Houston

9 6 October 2008 Questions