1. Lead from the front Texas Nodal http://nodal.ercot.com 1 Texas Nodal Market Management System Update on TPTF Comments on MMS Clarification Notes May 21, 2007 Xingwang Ma, Mark Patterson MMS Project Team

2. Lead from the front Texas Nodal http://nodal.ercot.com 2 What to report  MMS Clarification Notes presented on May 07, 2007 TPTF meeting  Comments on most items provided by Reliant  Comments on DSR OS provided by GP&L  Proposed Actions on Clarification Note Items

3. Lead from the front Texas Nodal http://nodal.ercot.com 3 SCED Timestamp  Current design has the SCED timestamp set to the wall clock time when SCED execution starts – i.e. the time when the latest telemetry, offers, generation to be dispatched is input to the SCED process. Should SCED time stamp to be the wall clock time at the completion of SCED run? i.e. The time when Base Point becomes effective (the time stamp used for Real Time Settlement Point Price Calculation, Base Point deviation charge calculation, time stamp telemetered to QSE etc)  Reliant: Yes. I think the protocols state that the time weighting of the prices from SCED is applied at the time the prices become effective. Prices can not be effective until they are calculated at the end of SCED.  ERCOT agrees with the above comment. Changes to design doc will be made.

4. Lead from the front Texas Nodal http://nodal.ercot.com 4 Clarification on NPRR005  Impact on DAM: Reallocation of MCFRI in the Day Ahead Market Process. Please see attached document “Reallocation of MCFRI in DAM.doc” (http://www.ercot.com/calendar/2007/05/20070507-TPTF.html) Reliant: I do not see what the question is?  NPRR005 describes that the reallocation of Flowgates is to be done “by 0600 prior to the DAM”  ERCOT recommends that MCFRI reallocation and SFT in DAM be coordinated. Day-ahead SFT will be done after 10:00 and prior to DAM execution.  ERCOT requested TPTF comments on ERCOT suggested change  From “by 0600 prior to the DAM” to “prior to execution of the DAM”.  ERCOT to submit NPRR  Reallocation of MCFRI prior to execution of the DAM

5. Lead from the front Texas Nodal http://nodal.ercot.com 5 Modeling of interruptible loads  Description of issue: The protocol assigns loads the parameters Minimum and Maximum Interruption Time and Minimum restoration time. These items refer to how long we can interrupt load in case of an event.. The current modeling requires that loads would need to be online to supply online reserve and offline to supply offline reserve.  Clarifications requested 1.The first issue we have is what is the meaning of Offline reserve from a load. Should that be allowed? Should load be allowed to submit a status as Offline? 2.The second issue is does ERCOT want the scheduling of reserve from load to obey these parameters, For the above example, should we allow reserve to be scheduled for all the hours 4 through 20 and interpret the parameters as instructions to the operator for cases when the reserve is actually be deployed and not as parameters for the optimization program as to when reserve can be scheduled. Should Load Parameters such as Max/Min Interruption Time, which are real time parameters, be enforced in procurement (DAM/SASM)?  Reliant: I think these times are for the IMM and PUCT Staff when they review the actual performance of an interruption. We should state that these parameters are for information only and are not part of any algorithm concerning dispatch of the Load Resources.  ERCOT to reflect the above suggested modeling of load parameters in design docs.

6. Lead from the front Texas Nodal http://nodal.ercot.com 6 Modeling of weekly energy constraints (RUC) Clarifications requested: (Reliant comments) A.The Maximum weekly starts/energy are only used for the weekly RUC problem. The weekly RUC would also observe the daily startup constraints. Agree B.Add a Maximum Daily Energy constraint in Resource Parameter if needed (need Protocols change). Not needed as the energy projection of a resource in RUC is almost meaningless when compared to actual energy of a RUCed unit. C.Market Participants can submit and update the Maximum daily starts/energy on daily basis, i.e. MPs manage the daily constraints by themselves. OK D.DRUC will enforce the maximum daily startup/energy constraints and will not enforce the weekly startup/energy constraints. OK E.HRUC will enforce the maximum daily startup/energy constraints and will not enforce the weekly startup/energy constraints. For HRUC, for the study period of the current Operating Day, the left over of daily startup/energy constraints from current Operating Day will be used; for the study period of the next Operating Day, the daily startup/energy constraints will be used. OK  ERCOT to reflect the comments in design docs  Maximum Daily Energy constraints are NOT modeled in DRUC and HRUC.

7. Lead from the front Texas Nodal http://nodal.ercot.com 7 DSR Output Schedule Validation in Real Time Clarification on changes to current design:  a check box will be added to the Energy Trade MPI for the QSE to specify whether the Energy Trade is for a DSR Generation Resource or not. i.e. When DSR QSE is submitting an Energy Trade, it should indicate whether the Energy Trade is for a DSR Resource or not.  Comments:  Reliant: Agree with recommendations.  GP&L suggested changes to the DSR validation A.DAM sales and purchases should be included in the DSR OS validation The error in the submitted Output Schedule is Sum of Output Schedule for the QSE – S um of Non-Spin deployment from the DSR Resource of the QSE – Sum of Energy Trades sold by the QSE for DSR + Sum of Energy Trades purchase by the QSE for DSR – QSE’s DSR Load –Sum of awarded energy offers in the DAM [sales] +Sum of awarded DAM energy bids [purchases] +Sum of static schedules for non-DSR base loaded generation. This could be Self Schedules or Energy Trades where the DSRQSE is both buyer and seller.  NPRR may be needed.

8. Lead from the front Texas Nodal http://nodal.ercot.com 8 NPRR for SURAMP :This was missed in NPRR049  Reliant: Not sure I agree with this comment. I do not see how the existing formula does not work correctly.  In NPRR049: SURAMP = MIN ([RAMPRATE– (RUSTELEM / 5)], [EMRRAMP – (RRSTELEM / 10)])  In this draft NPRR: SURAMP = [RAMPRATE– (RUSTELEM / 5)] RAMPRATE= Normal Ramp Rate when RRS is not deployed = Emergency Ramp Rate for Resources providing RRS when RRS is deployed, and Normal Ramp Rate for all other Resources.  ERCOT to submit NPRR

9. Lead from the front Texas Nodal http://nodal.ercot.com 9 Questions & Answers