TACOMA POWER S AVAILABLE TRANSFER CAPABILITY IMPLEMENTATION DOCUMENT PROCEDURE (ATCID)

Size: px

Start display at page:

Download "TACOMA POWER S AVAILABLE TRANSFER CAPABILITY IMPLEMENTATION DOCUMENT PROCEDURE (ATCID)"

Earl Curtis
6 years ago
Views:

1 PROCEDURE No: 2.0 TACOMA POWER S AVAILABLE TRANSFER CAPABILITY IMPLEMENTATION DOCUMENT The following NERC Reliability Standard(s) are associated with or apply to this document: Standard(s) MOD-001-1a MOD-029-1a Title/Description Available Transmission System Capability Rated System Path Methodology Table of Contents 1. Acronyms and Terms Procedure History... 9 FOR INTERNAL USE ONLY Page 1 of 9

2 1. Acronyms and Terms AFC Available Flowgate Capacity ATC Available Transfer Capability ATCID Available Transfer Capacity Implementation Document BPA Bonneville Power Administration CBM Capacity Benefit Margin ETC Existing Transmission Commitment NERC North American Electric Reliability Corporation NT Network Transmission PSE Puget Sound Energy PTP Point-To-Point TFC Total Flowgate Capability TRM Transmission Reliability Margin TTC Total Transfer Capability WECC Western Electricity Coordinating Council 2. Procedure 2.1 Tacoma Power uses the Rated System Path Methodology, as described in NERC Reliability Standard MOD-029-1a, for calculating its ATC for each ATC path within its transmission operating area. The ATC is calculated for each of the following time periods. Hourly values for at least the next 48 hours. Daily values for at least the next 31 calendar days. Monthly values for at least the next 12 months (months 2-13). 2.2 ATCID The Rated System Path Methodology (NERC MOD-029) has been implemented by Tacoma Power. The algorithms and components of the Rated System Path Methodology are listed below. WECC Operating Cases Load forecast Internal generation. Arranged Interchange. Contingencies. FOR INTERNAL USE ONLY Page 2 of 9

3 Points of Delivery/Points of Receipt. Existing PTP contracts and NT contracts. CBM and TRM, both are zero TTC Calculation The implementation of MOD-029 for calculating the TTC values for the applicable paths is documented in a Tacoma Power s document entitled Total Transfer Capability Algorithm ETC Calculation When calculating ETC for firm ETC for a specified period for an ATC Path, Tacoma Power uses the following algorithm: ETC F = NL F + NITS F + GF F + PTP F + ROR F + OS F Where: NL F is the firm capacity set aside to serve peak Native Load forecast commitments for the time period being calculated, to include losses, and Native Load growth, not otherwise included in TRM or CBM. NITS F is the firm capacity reserved for Network Integration Transmission Service serving Load, to include losses, and Load growth, not otherwise included in TRM or CBM. GF F is the firm capacity set aside for grandfathered Transmission Service and contracts for energy and/or Transmission Service, where executed prior to the effective date of a Transmission Service Provider s Open Access Transmission Tariff or safe harbor tariff. PTP F is the firm capacity reserved for confirmed PTP Transmission Service. ROR F is the firm capacity reserved for roll-over rights for contracts granting Transmission Customers the right of first refusal to take or continue to take Transmission Service when the Transmission Customer s Transmission Service contract expires or is eligible for renewal. OS F is the firm capacity reserved for any other service(s), contract(s), or agreement(s) not specified above using Firm Transmission Service as specified in the ATCID. The ETC in the MOD-029 standard is computed from the input data above, for firm ATC: NL F is equal to the applicable ATC Path s contribution from the Load Forecast minus the Internal Generation and adjusted for the Contingencies and any Arranged Interchange on the system. NITS F is equal to the applicable ATC Path s contribution from the NT contracts. GF F is equal to zero. FOR INTERNAL USE ONLY Page 3 of 9

4 PTP F is equal to the applicable ATC Path s contribution from the PTP contracts. ROR F is equal to the applicable ATC Path s contribution from any PTP or NT contract that is expiring and contains roll-over rights. OS F is equal to zero. When calculating ETC for non-firm Existing Transmission Commitments (ETC NF ) for all time horizons for an ATC Path, Tacoma Power will use the following algorithm: ETC NF = NITS NF + GF NF + PTP NF + OS NF Where: NITS NF is the non-firm capacity set aside for Network Integration Transmission Service serving Load (i.e., secondary service), to include losses, and load growth not otherwise included in TRM or CBM. GF NF is the non-firm capacity set aside for grandfathered Transmission Service and contracts for energy and/or Transmission Service, where executed prior to the effective date of a Transmission Service Provider s Open Access Transmission Tariff or safe harbor tariff. PTP NF is non-firm capacity reserved for confirmed PTP Transmission Service. OS NF is the non-firm capacity reserved for any other service(s), contract(s), or agreement(s) not specified above using non-firm transmission service as specified in the ATCID. At this time, under normal system conditions, Tacoma Power does not provide non-firm PTP transmission service. In the future, upon granting a customer request for a non-firm PTP transmission service agreement, Tacoma Power will include a calculation of non-firm ETC and non-firm ATC ATC Calculation When calculating firm ATC for an ATC Path for a specified period, Tacoma Power will use the following algorithm: ATC F = TTC ETC F CBM TRM + Postbacks F + counterflows F Where: ATC F is the firm Available Transfer Capability for the ATC Path for that period. TTC is the Total Transfer Capability of the ATC Path for that period. ETC F is the sum of existing firm commitments for the ATC Path during that period. FOR INTERNAL USE ONLY Page 4 of 9

5 CBM is the Capacity Benefit Margin for the ATC Path during that period. TRM is the Transmission Reliability Margin for the ATC Path during that period. Postbacks F are changes to firm ATC due to a change in the use of Transmission Service for that period, as defined in Business Practices. Counterflows F are adjustments to firm ATC as determined by the Transmission Service Provider and specified in the ATCID. When calculating non-firm ATC for an ATC Path for a specified period, Tacoma Power will use the following algorithm: ATC NF = TTC ETC F ETC NF CBM S TRM U + Postbacks NF + Counterflows NF Where: ATC NF is the non-firm Available Transfer Capability for the ATC Path for that period. TTC is the Total Transfer Capability of the ATC Path for that period. ETC F is the sum of existing firm commitments for the ATC Path during that period. ETC NF is the sum of existing non-firm commitments for the ATC Path during that period. CBM S is the Capacity Benefit Margin for the ATC Path that has been scheduled during that period. TRM U is the Transmission Reliability Margin for the ATC Path that has not been released for sale (unreleased) as non-firm capacity by the Transmission Service Provider during that period. Postbacks NF are changes to non-firm ATC due to a change in the use of Transmission Service for that period, as defined in Business Practices. Counterflows NF are adjustments to non-firm ATC as determined by the Transmission Service Provider and specified in the ATCID At this time, under normal system conditions, Tacoma Power does not provide non-firm PTP transmission service. In the future, upon granting a customer request for a non-firm PTP transmission service agreement, Tacoma Power will include a calculation of non-firm ATC. FOR INTERNAL USE ONLY Page 5 of 9

6 2.2.2 Counterflows When calculating firm ATC for an ATC Path, Tacoma Power sets the counterflows equal to zero. However, Tacoma Power accounts for confirmed transmission reservations, expected interchange, and internal counterflows for both firm and nonfirm ATC calculations by using the applicable data from modeled WECC base cases. Tacoma Power includes all counterflows at 100% when calculating ATC by incorporating it into the ETC calculation as a negative value. The rationale for treating counterflows as described above is consistency with current modeling techniques used by Tacoma Power in operating and planning studies Tacoma Power obtains data for use in calculating ATC or AFC from WECC base cases. These base cases are developed from the data provided by the Transmission Operators and Transmission Service Providers located within the WECC region. Tacoma Power provides data for use in calculating ATC or AFC to WECC for WECC s use in modeling base cases. These base cases are accessible to the Transmission Operators and Transmission Service Providers within the WECC region Tacoma Power s allocation processes The allocation processes are described in the applicable agreements. If no agreement exists, then the transfer or flowgate will be allocated on a first-come, firstserved basis Effect of generation and transmission outages are considered in transfer or flowgate capability calculations All planned and unplanned generation and transmission outages in the Tacoma Power system are considered in transfer or flowgate capability monthly calculations Since the impacts of outages from other Transmission Service Providers to Tacoma Power are minimal, outages from other Transmission Service Providers that cannot be mapped to the Transmission model used by Tacoma Power to calculate transfer or flowgate capability are not considered. 2.3 Notification of ATCID Tacoma Power notifies the following entities before implementing a new or revised ATCID: Tacoma Power s Planning Coordinator WECC as Tacoma Power s Reliability Coordinator Tacoma Power s Transmission Operator PSE and BPA as Tacoma Power s adjacent Planning Coordinators and adjacent Transmission Service Providers. FOR INTERNAL USE ONLY Page 6 of 9

7 2.4 Availability of the current ATCID Tacoma Power has made its current ATCID available to all the entities specified above. 2.5 Assumptions for calculating TTC When calculating TTC or TFC, Tacoma Power will use assumptions no more limiting than those used in the planning of operations for the corresponding time period studied, providing such planning of operations has been performed for that time period. 2.6 Assumptions for calculating ATC or AFC When calculating ATC or AFC Tacoma Power will use assumptions no more limiting than those used in the planning of operations for the corresponding time period studied, providing such planning of operations has been performed for that time period. 2.7 Frequency of ATC calculation Tacoma Power will recalculate ATC at a minimum on the following frequency, unless none of the calculated values identified in the ATC equation have changed: Hourly values, once per hour. Transmission Service Providers are allowed up to 175 hours per calendar year during which calculations are not required to be performed, despite a change in a calculated value identified in the ATC equation Daily values, once per day Monthly values, once per week. 2.8 Making the requested data available Tacoma Power will begin to make the following requested data available to the requestor within thirty calendar days of receiving a request from any Transmission Service Provider, Planning Coordinator, Reliability Coordinator, or Transmission Operator for data from the list below solely for use in the requestor s ATC or AFC calculations, subject to the conditions specified in 2.9. Expected generation and Transmission outages, additions, and retirements. Load forecasts. Unit commitments and order of dispatch, to include all designated network resources and other resources that are committed or have the legal obligation to run, as they are expected to run, in one of the following formats chosen by the data provider. o Dispatch Order o Participation Factors o Block Dispatch Aggregated firm capacity set-aside for Network Integration Transmission Service and aggregated non-firm capacity set aside for Network Integration Transmission Service (i.e. Secondary Service). Firm and non-firm Transmission reservations. Aggregated capacity set-aside for grandfathered obligations. Firm roll-over-rights. FOR INTERNAL USE ONLY Page 7 of 9

8 Any firm and non-firm adjustments applied by the Transmission Service Provider to reflect parallel path impacts. Power flow models and underlying assumptions. Contingencies, provided in one or more of the following formats: o o o A list of Elements A list of Flowgates A set of selection criteria that can be applied to the Transmission model used by the Transmission Operator and/or Transmission Service Provider Facility Ratings. Any other services that impact Existing Transmission Commitments (ETC). Values of Capacity Benefit Margin (CBM) and Transmission Reliability Margin (TRM) for all ATC Paths or Flowgates. Values of Total Flowgate Capability (TFC) and AFC for any Flowgates considered by the Transmission Service Provider receiving the request when selling Transmission service. Values of TTC and ATC for all ATC Paths for those Transmission Service Providers receiving the request that do not consider Flowgates when selling Transmission Service. Source and sink identification and mapping to the model. 2.9 Data Request Conditions a. Tacoma Power shall make its own current data available in the format it maintains for up to 13 months into the future (subject to confidentiality and security requirements). b. If Tacoma Power uses the data requested in its transfer or Flowgate capability calculations, it shall make the data used available. c. If Tacoma Power does not use the data requested in its transfer or Flowgate capability calculations, but maintains that data, it shall make that data available. d. If Tacoma Power does not use the data requested in its transfer or Flowgate capability calculations, and does not maintain that data, it shall not be required to make that data available. e. This data shall be made available by Tacoma Power on the schedule specified by the requestor but no more frequently than once per hour, unless mutually agreed to by the requester and Tacoma Power. FOR INTERNAL USE ONLY Page 8 of 9

9 3. History Number Change Summary Reviewers Initial document creation Tom Anderson, Shirley Eshbach, Keith Morisette, Joseph Wilson, Khanh Thai Annual Review and update. Major revisions for MOD a: clarification of non-atc offering TTC calculation clarification Shirley Eshbach, Keith Morisette, Joseph Wilson, Khanh Thai 2.0 Annual Review and update: In response to recommendation from MOD-029 Mock Audit, included the algorithms for R5, R6, R7 and R8 in the ATCID. Shirley Eshbach, Keith Morisette, Joseph Wilson, Khanh Thai FOR INTERNAL USE ONLY Page 9 of 9

ISO New England Available Transfer Capability. Implementation Document. Version 1.0

ISO New England Available Transfer Capability Implementation Document Version 1.0 1 Effective: 04/01/2011 Table of Contents 1. Introduction... 3 2. Transmission Service in the New England Markets... 6