Texas Nodal Load Frequency Control (LFC) EDS 3 R6 Texas Nodal Load Frequency Control (LFC) EDS 3 R6.3 EDS 3 Release 6 LFC Workshop October 10, 2007 http://nodal.ercot.com 1

LFC – R6.3: LFC Total System Test Presentation: R6.3 Overview Additional Pre-requisites R6.3 Test Procedure FAQ’s and Discussion http://nodal.ercot.com 2

LFC – R6.3: LFC Total System Test Overview – Testing scheduled between June and August (completed before the EDS 4 R9, 168 hour test) ERCOT to verify the ability to control system frequency with LFC with all QSE and Resources (total system) providing Regulation and following Base Point in Nodal. Verify LFC’s ability to meet NERC control systems performance criteria Will require three tests of approx. 2, 8 and 48 hours. A QSE’s Resource(s) must have displayed the ability to follow Regulation instructions during EDS 3 R6.2 testing in order to provide Regulation during EDS 3 R6.3. http://nodal.ercot.com 3

LFC – R6.3: LFC Total System Test Market Participant Involvement – All QSE’s providing Regulation will be required to follow the Regulation instructions from Nodal (LFC). Each Resource obligated to provide Regulation must deploy Regulation during the test period as per the Nodal Regulation signal and the telemetered Participation Factor. Ratio of the Regulation obligation of the QSE under test to the total ERCOT requirement will be based on the outcome of the Zonal Ancillary Service Market SCED will calculate 5 minute Base Points, and the QSE must follow the LFC 4 second Updated Desired Base Point. All QSE’s must provide Energy Offer Curves for SCED, which will be representative of the same QSE portfolio Balancing Energy Service submitted in the Zonal system. http://nodal.ercot.com 4

LFC – R6.3: LFC Total System Test Market Participant Involvement – QSEs will continue to update their Resource Plans, Base Power Schedules and Zonal portfolio Offers during the test periods. The constraints activated in Zonal will also be active in Nodal. QSEs shall continue to update their Zonal schedules and Balancing Energy Service offers. During the test, QSEs should follow the LFC 4 second Updated Desired Base Point provided by the Nodal system and ignore the OOME Dispatch Instructions from the Zonal system. http://nodal.ercot.com 5

LFC – R6.3: Additional Pre-requisites SCED Pre-requites – EDS3 Release 5 - SCED Completed Submit and adjust Energy Offer Curves and Resource Output Schedules using MIS user interface or machine-to-machine interfaces    Download and review SCED Base Points for Resources through MIS user interface or machine-to-machine interfaces Review LMPs  SCED Validation Includes MP Input Validation SCED testing with ICCP (Third phase of SCED testing, Offer Curves will be created by MPs based on the defined formula and methodology as outlined in the Nodal Transition Plan). Six Month LMP complete (initial period use SCED MP offer methodology, second period allow MPs to submit any Offers and Output Schedules) Will need a test where offers are submitted to match Zonal bids Compare SCED results to Zonal dispatch for agreement http://nodal.ercot.com 6

LFC – R6.3: Additional Pre-requisites TCM/RTCAM Prerequisites – A Comparison test of TCM to RTCAM will be performed prior to R6.3 tests. Test TCM for correct shift factors, same Generator dispatch direction (raise or lower) and similar MW amounts. Both real-time contingency analysis (RTCA) and CA within the study network sequence (STNET) will be required to compute shift factors and hence will have NETSENS tightly integrated. RTCAM and TCM both set to a 3% cutoff for Gen Shift factors http://nodal.ercot.com 7

LFC – R6.3: Test Procedure (Entrance and Execution) Abort ERCOT complete all Pre-requisites and system checks No Request one QSE to Nodal System stable Correct Problem No All QSE’s on Nodal Yes No Monitor System and Record Data Yes A http://nodal.ercot.com 8

LFC – R6.3: Test Procedure (Exit) No Correct Problem Request one QSE to Zonal System stable A All QSE’s on Zonal Yes No End of Test Yes http://nodal.ercot.com 9

LFC – R6.2: FAQ’s FAQ’s and Discussion http://nodal.ercot.com 10

A role call of QSE’s will be performed before the test. LFC – R6.2: FAQ’s Q: How will ERCOT communicate instructions to discontinue the test or to switch between Zonal and Nodal control once the test has begun? A: All communication and instructions during the test will be done through the ERCOT Control Room Operator. A conference call number (and a secondary back-up) will be provided before the test, and will allow open communications between ERCOT and all MPs at all times during the test. A role call of QSE’s will be performed before the test. See previous slides on Test Procedure ‘Entrance and Exit’ steps. http://nodal.ercot.com 11

LFC – R6.2: FAQ’s Q: How will ERCOT coordinate the selection of active constraints for RTCAM and SCED? A: The constraints activated in Zonal System during the test will also be activated in the Nodal system and will be coordinated by the ERCOT Control Room Operator. ERCOT will monitor the active constraints in Zonal and Nodal and the relevant shift factors to ensure the expected actions are occurring. Managing constraints in Zonal and Nodal will be a pre-requisite ‘test’ for ERCOT to complete before scheduling the Total System test. http://nodal.ercot.com 12

LFC – R6.2: FAQ’s Q: Will the same power flow solutions be used in both Zonal and Nodal congestion management systems? A: Zonal and Nodal will be operating from different State Estimators, but both will have the same power flow solutions The Nodal EMS State Estimator, Constraint Equations and Power Flow solutions are verified in EDS 2 Release 3. http://nodal.ercot.com 13

Q: How will ERCOT calculate its CPS1 and CPS2 test scores ? A: LFC – R6.2: FAQ’s Q: How will ERCOT calculate its CPS1 and CPS2 test scores ? A: The ERCOT Nodal EMS will calculate and store the CPS1 and CPS2 scores. ERCOT will validate the scores and report the results to the market. http://nodal.ercot.com 14

Discussion and Questions? LFC – R6.2: Questions? Discussion and Questions? Thank you. EDS3@ercot.com http://nodal.ercot.com 15