Lead from the front Texas Nodal 1 External Web Services Update Nodal Implementation Team Presentation July 7, 2009

Lead from the front Texas Nodal Agenda External Interface Specification –Additional v1.19 comments received since last meeting EIS Market Information Services Update –Further discussion of removal of certain interfaces Q&A

Lead from the front Texas Nodal Overview EIS 1.19 was released for comment on 6/5/09 Comments closed on 6/19/09 –Received several comments Friday afternoon 6/19/09, too late for detailed discussion at the last meeting Sandbox –1.19 is being released to the Sandbox today, 7/7/09

Lead from the front Texas Nodal Comments / Questions Received Review Comments / Questions Received

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review Total of 19 items from the Market Information section of the document (read-only interfaces) initially targeted for removal from EIS/EWS implementation 9 items called out for additional review –Limited Review: we extended the deadline for receiving comments and questions for the 19 interfaces, which were due 7/2/09 –8 items on this list already identified for further ERCOT evaluation by the NIT, 1 was added as a result from comments received These are items that are not suitable to be provided via web services for various reasons –All are available through other means except the four items that lack protocol traceability

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review 1)EIS Section , Responsive Reserve Capacity 2)EIS Section , Non-Spinning Reserve 3)EIS Section , Undeployed Reg-Up and Reg-Down 4)EIS Section , Available Capacity 5)EIS Section , Total ERCOT Generation Operating Reserve Resolution: These 5 sections will be combined into one interface called System Parameters This information is also provided in one MIS display (System Parameters) EIP will create a new web service that offers similar functionality as the System Parameters display. EIP implementation will cache the last good reading from MIS and will feed that to all incoming web service requests for SystemParameters noun Only returns current information. No history will be provided. This data is also provided via ICCP

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review 1)EIS Section , Responsive Reserve Capacity 2)EIS Section , Non-Spinning Reserve 3)EIS Section , Undeployed Reg-Up and Reg-Down 4)EIS Section , Available Capacity 5)EIS Section , Total ERCOT Generation Operating Reserve Resolution (cont’d): A decision was made at March 31, 2008 TPTF regarding the AS Capacity Monitor Data (the title of the Protocol Section , Ancillary Services Capacity Monitor, that describes the provision of this data to the market) “Ancillary Service (AS) Capacity Monitor Data Ms. Flores discussed issues for meeting the required ten-second posting frequency for AS Capacity Monitor data, noting that testing indicated the data could not be generated more frequently than once per minute. However, if the data was provided via web service, it could be refreshed per the ten-second requirement. The web-service option would not allow the data to be captured historically. No one objected to this approach. Ms. Flores noted that she could withdraw NPRR121, System Parameters Posting Frequency, in favor of the web service option"

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review 6)EIS Section , Dynamic Ratings Status: The current MIS report posting for dynamic ratings contains hourly data for the real-time + next 7 days, and uses current + forecasted weather assumptions No MIS report or requirement for real-time dynamic ratings adjusted to the actual temperature, refreshed every 5 minutes. This data will not be provided via ICCP as there is no requirement ERCOT needs more time to evaluate what is needed beyond the current implementation

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review 6)EIS Section , Dynamic Ratings Relevant Protocols and planning postings to satisfy: 3.10(4): For each model, ERCOT shall post ratings and the ambient temperatures used to calculate the ratings on the MIS Secure Area when the model is published. –This will be posted with the model (3): Each Operating Hour, ERCOT shall post on the MIS Secure Area updated Dynamic Ratings adjusted for the current temperature. –This is the CDR report referenced previously (posted hourly with 7 days of data) 4.2.3(b) Weather assumptions used by ERCOT to forecast ERCOT System conditions and used in the Dynamic Rating Processor –This is a different CDR report posting daily at (1): ERCOT shall post summaries of dynamically adjusted Transmission Element limits on the MIS Secure Area in a form that allows Market Participants to directly upload Real-Time data into the Common Information Model (CIM) –This is under evaluation (1): ERCOT shall provide a system to accept and implement Dynamic Ratings or temperatures to be applied to rating tables for each hour in the Day- Ahead and in the Operating Hour –ERCOT receives this information via ICCP

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review 7)EIS Section , List of Zones, Hubs or Buses Resolution: Current implementation is to get this via the Network Model posting on the MIS This is still under evaluation to satisfy business and technical needs 8)EIS Section , Derated CRRs Resolution: For shadow settlements, data is available in the DAM extracts No protocol traceability for posting this information in a report on the MIS A NPRR would need to be submitted 9)EIS Section , Unit Availability Resolution: No protocol traceability for this posting this information A NPRR would need to be submitted

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review Summary Of the 19 items from the Market Information section initially targeted for removal from EIS/EWS implementation: –5 will be developed as a new single interface –2 are still under evaluation –12 will be removed from the EIS specification document 4 not in protocols 51 Market Info interfaces 19 interfaces under review 7 provided other mechanism 2 still under evaluation 5 will be new interface

Lead from the front Texas Nodal EIS Market Information Services Update: Interface Review Summary (cont’d) Targeted for removal from document: Voltage Profiles Total Regulation Load Distribution Factors Shift Factor Customer Load Profile Unit Availability Derated CRRs Area Control Error Frequency Dynamic ratings deviation adjusted Average monthly Dynamic deviation Total ERCOT Generation Still under evaluation: Dynamic ratings List of Zones, Hubs, or Buses