Texas Nodal Load Frequency Control (LFC) EDS 3 R6.1 EDS 3 Release 6 LFC Workshop October 10, 2007

1. Texas NodalLoad Frequency Control (LFC)EDS 3 R6.1EDS 3 Release 6 LFC WorkshopOctober 10, 2007 http://nodal.ercot.com 1

2. LFC – R6.1: ACE Calculation and Precondition Validation Presentation – • R6.1 Overview • R6.1 Testing • FAQ’s and Discussion http://nodal.ercot.com 2

3. LFC – R6.1: ACE Calculation and Precondition Validation Overview – • Testing performed January to February. • ERCOT will compare the Nodal ACE results with the Zonal ACE results to test accuracy for a continuous 7-day period. • ERCOT will verify with each QSE with Resources the outputs produced by the Resource Limit Calculator (RLC). • ERCOT will verify it’s ability to calculate and issue Emergency Base-Points along with the Emergency Base-Point Flag and will also verify the ability of each QSE with Resources to receive both the Base-Point and the Flag. http://nodal.ercot.com 3

4. LFC – R6.1: ACE Calculation Verification ACE Calculation Verification – • Performed solely by ERCOT and will require no Market Participation involvement • Compare raw Nodal ACE to raw Zonal ACE • Done every 4 seconds for consecutive 7-day period • Should be the exact same values • Comparison will also be done between the processed Zonal and Nodal ACE values as part of the LFC tuning process http://nodal.ercot.com 4

5. LFC – R6.1: RLC Output Verification RLC Output Verification – • QSEs with Resources will be tested one at a time • Physical Resources will continue to be controlled by the Zonal system • The QSE participating in the test will choose several of it’s Resources with which to validate the ERCOT RLC calculations and will manually change the following Nodal EMS points for those Resources one at a time: • Output MW • High- and Low-Sustainable Limits (HSL and LSL) • Reg-Up and -Down Ancillary Service Resource Responsibility • Responsive Reserve Ancillary Service Schedule • Non-Spin Ancillary Service Schedule • These points will be sent to ERCOT via ICCP http://nodal.ercot.com 5

6. LFC – R6.1: RLC Output Verification cont.. RLC Output Verification – • ERCOT will also activate the Responsive Reserve deployment flag and verify changes to RLC calculations. • The following RLC outputs will be checked: • Resource High- and Low-Ancillary Service Limit (HASL and LASL) • Resource SCED Up and Down Ramp Rate (SURAMP and SDRAMP) • Resource High- and Low-Dispatch Limit (HDL and LDL) • The RLC values are calculated as per the Nodal EMS Design documents as found on the ERCOT Nodal Website • Prior to the test, QSEs will have provided ERCOT with a completed R6.1 Test Form http://nodal.ercot.com 6

7. All QSEs Nodal SCED HDL, LDL HASL, LASL, SURAMP,SDRAMP. Data Limits Data RLC MMS SCADA ICCP Single QSE Nodal ERCOT to verify results with QSE LFC – R6.1: RLC Output Verification Test Process http://nodal.ercot.com 7

8. LFC – R6.1: RLC Output Verification Test Procedure • R6.1 Test Form Example • - Low Ancillary Service Limit http://nodal.ercot.com 8

9. LFC – R6.1: Emergency Base-Point Verification Emergency Base-Point Verification – • Ideally Emergency Base Point testing will be performed immediately before or after the RLC output verification • As a precondition, ERCOT will have verified that the Emergency Base-Point calculator values are calculated in the ERCOT Nodal system as expected per the Nodal EMS Design documents • ERCOT will manually enter a predetermined incremental MW value and trigger the LFC Emergency Base-Point calculator • The QSE will be asked to verify that they have received both the newly calculated Base-Point and the system-wide Emergency Base-Point flag http://nodal.ercot.com 9

10. All QSEs Nodal SCED ERCOT Calculate the EMERGENCY BASE POINT Data Calc Limits Data RLC & LFC MMS SCADA ICCP XML ERCOT to verify results with QSE Single QSE Nodal Base Point Emergency Base Point Flag ICCP Base Point ICCP LFC – R6.1: Emergency Base-Point Verification Test Procedure http://nodal.ercot.com 10

11. LFC – R6.1: FAQ’s FAQ’s and Discussion http://nodal.ercot.com 11

12. LFC – R6.1: FAQ’s Q: Will data from the Nodal Resource Asset Registration Form (RARF) be used for Ramp Rate in the RLC calculations? A: Although there are Ramp Rate ICCP points for Resources, the Ramp Rates that are used as the input for the RLC calculations come from the Market Management System database (Ramp Rates provided from the RARF). http://nodal.ercot.com 12

13. LFC – R6.1: FAQ’s Q: Describe how the RLC outputs will be fed back to the QSEs? How will QSE questions about the data be addressed? A: During the test, an ERCOT Test Operator will be verifying the input changes and outputs with the QSE. ERCOT will record the test results on the R6.1 test form and a copy of those results will be sent to the QSE. ERCOT will attempt to resolve any issues or discrepancies with the QSE during the test or during a post investigation. If the QSE or ERCOT deem it necessary, another test can be scheduled. http://nodal.ercot.com 13

14. LFC – R6.1: Thank You Thank you. EDS3@ercot.com http://nodal.ercot.com 14