1. Texas Nodal Electrical Buses and Outage Scheduling

2. Electrical Bus Definition as Proposed in NPRR 63 Electrical Bus A physical transmission element defined in the Network Operations Model that connects, using breakers and switches, one or more Loads, lines, transformers, generators, capacitors, reactors, and phase shifters to the ERCOT Transmission Grid where there is negligible impedance between the connected transmission elements. All Electrical Buses are designated by ERCOT and TSPs for modeling the electrical topology of the ERCOT Transmission Grid.

3. Electrical Buses and the Outage Scheduler Section 3.1.5.1- ERCOT Evaluation of Planned Outage and Maintenance Outage of Transmission Facilities 1. A TSP shall request a Planned Outage or Maintenance Outage for any Transmission Element in the Network Operations Model that requires the Transmission Element to be removed from its normal service. Proposed Transmission Planned Outage or Maintenance Outage information submitted by a TSP in accordance with this Section constitutes a request for ERCOT’s approval of the Outage schedule associated with the Planned Outage or Maintenance Outage. ERCOT is not deemed to have approved the Outage schedule associated with the Planned Outage or Maintenance Outage until ERCOT notifies the TSP of its approval under procedures adopted by ERCOT. ERCOT shall evaluate requests under Section 3.1.5.11, Evaluation of Transmission Facilities Planned Outage or Maintenance Section 2 - Definitions and Acronyms Transmission Element: A physical transmission facility that is either a Electrical Bus, line, transformer, generator, load, breaker, switch, capacitor, reactor, phase shifter, or other similar device that is part of the ERCOT Transmission Grid and defined in the ERCOT Network Operations Model.

4. Electrical Buses in the Network Model as presented at the 6/25 TPTF meeting Approximately 18,000  Generator buses  Load buses  Settlement Points  Operational buses Electrical Buses and the Outage Scheduler In this example none of the 5 potential Electrical Buses would be included in the Network Model or be available for outage scheduling unless it was a settlement point or requested by a TO subset

5. Electrical Buses and the Outage Scheduler ERCOT proposes no changes to the Nodal Protocols ERCOT interprets 3.1.5.1 to mean that every outaged element (including the new subset of electrical buses) will be a separate entry in the Outage Scheduler 1.Avoids conflict with the Forced Outage Detector 2.Enhances Situational Awareness 1.Operational 2.MIS 3.Allows accurate reporting 1.Nodal Metrics 2.NERC TADS 3.Internal Operational Reports 4.Insures consistent outage submission by all TOs Tracer Program will treat electrical buses like lines and transformers

6. Electrical Buses and the Outage Scheduler Options Option 1 – “ERCOT’s Proposed Option  No Protocol Change  No O.S. Modification  No Extra Cost  No Time Delay  Requires TOs to enter all elements including new subset of E.B’s. Option 2 – “No Electrical Bus Option”  Protocol Change  No O.S. Modification  No Extra Cost  Time Delay  Requires TOs to enter all Elements except E.B. Insert “except Electrical Buses” Into 3.1.5.1 section of Nodal Protocols Option 3 – “Topology Processor Option”  No Protocol Change  O.S. Modification  Extra Cost  Large Time Delay  TOs could enter only elements necessary to interrupt powerflow. A topology processor would have to be added to the O.S. design

7. The End? Questions?