Constraint Schedule Management

Constraint Schedule Management February 7, 2006

Agenda • What is CSM? • Workshop Goals • Background • The Conceptual Design • What’s Next

What is CSM? TBL’s proposed method for managing it’s network flowgate ATC & constraints: • Based on nodal Sources and Sinks • Utilizing Reservation, e-Tag, Generation & Load Forecast information to apply predictive and proactive analysis to make commercial transmission decisions • Strives to prevent flows exceeding flowgate OTC whenever possible • Endeavors to use industry standard tools and processes while supporting our Tariff

Workshop Goals • Describe the work that preceded this meeting • Demonstrate that BPA’s internal network is constrained • Clarify TBL’s approach to studying CSM • Provide detail for some CSM conceptual design elements: • Source/Sink vs. POR/POD • PUFs & the Nodal Concept • Impacts on reservations & the predictive reservation process • Impacts on scheduled transactions • Impacts on non-scheduled transactions • Curtailments • Redispatch of non-scheduled transactions • Identify the design elements the CSM team will be defining in the upcoming weeks • Communicate the public involvement process & upcoming timeline

How We Got Here: Background • Picked up from where regional CSM team left off • Evaluated 6 options • Selected nodal grouping option combined with reservation impact deeming option based on TBL criteria. • Started out assuming we would calculate flowgate impacts based on nodal PORs & nodal PODs • Held two customer workshops & numerous customer meetings • Conducted extensive internal analysis & design development efforts

CSM Options Considered: Background OATT 33.2 – 33.5

NW Transmission System Problems During Summer OperationBPA Transmission Business LineMike VilesJanuary 2006

Transmission Loading Characteristics • NW load peaks in Winter • Heaviest power flows are east to west • California peaks in Summer • Heaviest power flows are north to south

Figure 1: NW Paths & Seasonal Direction of Powerflow Summer Transfers Winter Transfers Constrained Transmission Path

Summer 2005 Problem Areas • North of Hanford Path • Monitors flow of power on two 500-kV lines on eastside of Cascade Mountains. • Paul-Allston Path • Monitors flow of power on two 500-kV lines between Olympia and Longview. • Allston-Keeler Path • Monitors flow on one 500-kV line between Longview and Portland

Problems • Exceeding the Operational Transfer Capability (OTC) of these paths • Operating above an OTC creates risk of unreliable system response to critical contingences • WECC requires that the actual flow on these paths get below the OTC within 30 minutes

Response to OTC Excursions • In August 2005 there were 29 periods when the OTC of one of these paths was exceeded for at least 5 minutes (Table 1) • 20 of these OTC excursions required dispatcher action to reduce the flow on the path (Table 2) • In some cases, the dispatcher action is significant

Summary of System Problems During Summer Operation • The transmission system was operated “closer to the edge” in summer 2005 than summer 2004 and 2003 (i.e., more OTC excursions) • OTC excursions can result in significant dispatcher action to control

What We Learned from You: Background • Changing current PORs & PODs to nodal PORs & PODs would have a negative impact with minimal benefit • Flowgate impact assessment based on POR/PODs reflects only one segment of the whole transaction and is not accurate in many cases • Using nodal source & nodal sink data provides more accurate flowgate impact analysis • Requiring additional schedules for in-control-area NT transactions would not be viable • Achieving the CSM objectives without affecting the customers’ reservation process would be beneficial

CSM Conceptual Design Source/Sink vs. POR/POD • Technical analysis indicated that POR/POD (previous concept) did not provide true indication of flowgate impacts • Examination of the reservation & e-Tag model revealed that Source & Sink (if specific enough, i.e. nodal) provides true indication of energy flows • With the accurate impacts of each schedule known (via nodal Source and Sink): • Non-Firm ATC inventory can be calculated for internal flowgates • ATC impacts of a reservation on the network flowgates can be computed • The non-firm flows can be effectively managed separately from the firm flows • Relief on a flowgate during a constraint can be effective without being unduly discriminatory

CSM Conceptual Design Source/Sink vs POR/POD (Example #1):

CSM Conceptual Design PUFs & the Nodal Concept: • PUFs are an impedance based measurement of the electrical system impacts of an injection of energy into and withdrawal out of the interconnected WECC transmission system • TBL has developed a methodology for grouping electrical system sources & sinks (customer delivery points & generation integration points) into “Nodes” that have similar electrical effects on all BPA network flowgates • Using these nodes in conducting transmission business allows TBL to calculate the impacts on our flowgates, while minimizing the amount of detailed data required • A grouping of electrical system sources & sinks with +/- 10% similarity is proposed as the starting point for discussion • This concept is portable to other control areas’ systems and flowgates

CSM Conceptual Design PUFs & the Nodal Concept (continued): +/- 10%

CSM Conceptual Design Making Transmission Reservations: • No change required in POR/POD granularity for making a transmission request in any market • Nodal source & nodal sink will not be required on reservations • Specification of nodal source & nodal sink will be optional for reservations • If nodal source and sink are provided, the schedule source/sink nodes must match those in the reservation at the nodal level • Using nodal sources and sinks to assess ATC impact allows TBL to look at the impact of all segments of the transaction

CSM Conceptual Design Determining Reservation Impacts: • If you do specify a nodal source & sink, the flowgate impacts of the request will be based on specified nodal source(s)/sink(s) • If you do not specify a nodal source & sink, the flowgate impacts of the request will be based on deemed nodal source(s)/sink(s) • The deemed nodal source(s)/sink(s) will be determined using past scheduling activity on similar reservations • Deemed nodal source(s)/sink(s) will be transparent to the requestor • A scenario analyzer will allow the requestor to view the deemed impacts • You can assess the deemed source(s)/sink(s) to determine whether or not to specify a nodal source/sink • The deeming algorithm will be continuously tested and refined

CSM Conceptual Design Impacts on Scheduled Transactions: • All of the sources & sinks required on TBL schedules must be at a nodal level of granularity • Flowgate impacts of scheduled transactions will be computed using nodal source & sink data for purposes of: • Calculation of HNF ATC • Calculation of curtailment distributions across products, customers and transactions • Transmission tagged & scheduled to deliver consolidated generation (like BPASLICE) will need to be scheduled using nodal sources • Transmission tagged & scheduled to serve consolidated load (like BPAPOWER), will need to be scheduled using nodal sinks

CSM Conceptual Design Impacts on Non-Scheduled Transactions: • Non-scheduled transactions must provide their appropriate share of congestion relief • TBL has developed a CSM concept for managing the portion of congestion caused by non-scheduled NT transactions served by federal power sales • This concept does not require these transactions to be scheduled if they are not scheduled today • This concept is based on determining flowgate impacts of non-scheduled transactions served by federal power sales by performing a powerflow analysis using nodal load forecasts and nodal federal power sales patterns

CSM Conceptual Design Curtailments: • Flowgate impacts must be calculated for all known network flows (scheduled & non-scheduled) in order to enable network curtailment/redispatch • All scheduled transactions must be curtailed via the e-Tag • Distribution of curtailment MW’s amongst transactions will be determined based on “effective” and “non-discriminatory” requirements in the TBL OATT • TBL will use NERC priorities for curtailments

CSM Conceptual Design Redispatch of Non-Scheduled NT Transactions: • TBL is required to reduce firm NT and PTP flowgate impacts simultaneously & equitably to manage a constraint • “Attachment K” to the TBL OATT provides guidance about NT redispatch for the applicable rate period

CSM Conceptual Design Redispatch of Non-Scheduled NT Transactions (continued): • Our Design: • Calculate the pro rata share of non-scheduled federal NT service and scheduled service impacting a flowgate • Relieve congestion via federal redispatch for non-scheduled federal NT service • Relieve the balance of the congestion via curtailment of schedules • TBL will obtain the federal generator base points on a nodal level (updated as needed) • TBL will require timely and accurate nodal NT load forecasts • A power flow using this data will determine the flowgate impacts of non-scheduled NT service • This allows for calculation of the redispatch requirements to relieve the NT portion of the flowgate constraint if needed

CSM Conceptual Design Sequence of Constraint Relief: Curtail PTP Non-Firm Secondary (1-NS) Curtail PTP Non-Firm Hourly (2-NH) Curtail Non-Firm Network (6-NN) Scheduled Transactions (7-F) Non-Scheduled Transactions Redispatch (OATT Attachment K) for federal Hydro-served NT Load in the BPA Control Area OATT Curtailments Non-OATT Curtailments Load Shedding

CSM Conceptual Design What We’re Currently Working On: • Precisely how ATC will be calculated & managed for all markets? • What method will be used to determine which Non-Firm schedules are cut during a curtailment? • What method will be used to determine which Firm schedules are cut during a curtailment? • Affects on Energy Imbalance?

CSM Conceptual Design Future Analysis: • Will LTF contract holders be held to scheduling practices using nodal sources and sinks consistent with the PORs/PODs requested in their contract? • How will CSM affect: • Loss returns • Federal reserve obligations • Dynamic schedules • Slice • AGC (both for us and for adjacent CA’s)

What’s Next? Phase 2 of Conceptual Design Rollout: • Targeted for Spring, 2006 • TBL will share our proposed design for implementing ATC, Non-Firm & Firm curtailments on the network and energy imbalance • Share the remainder of proposed design • Provide forum for CSM model discussion & answering questions • Clarify any restrictions regarding the use of long-term contracts in scheduling • Provide you with a template for documenting the impacts of implementing CSM on your business & systems

What’s Next? Impact Analysis of Conceptual Design: • You will have a 60-day comment period • We are available to work with you at your request in assessing the impacts of the proposed CSM design on your organization • We will compile all customer impacts • We will schedule an impact review session during a customer workshop • Reevaluate design if necessary based on impacts

What’s Next? Implementation Activities: • TBL will work with its adjacent control areas to implement changes to their registered sources & sinks to be nodal • TBL will include a test period in the implementation plan to measure and improve CSM processes before use in curtailment and redispatch • Implementation will be phased into logical segments • TBL will provide substantial communication to customers leading up to and throughout the implementation process

What’s Next? Decision Point: • Sponsor Go/No-Go Implementation Decision • Targeted for June of 2006 • Based on: • Completed conceptual design • Completed business case • Proposed implementation plan (high level) • Customer impacts data and summarization

Thank you Your comments are appreciated!

Constraint Schedule Management