1. Purpose This document outlines the transfer capability on MATL Path 83 for both long-term capability and for current seasonal capabilities adjusted for known System Operating Limits (SOLs), such as adjacent system constraints that limit the Available Transfer Capability (ATC) and operating configurations for MATL that reduce the ATC. MATL s Path 83 transfer capability adjusted for such SOLs becomes the basis for the current year s short-term ATC. 2. References MATL 2007 Phase II Path Rating Study Report MATL 2012 Phase II Path Rating Study Report MATL Summer 2013 SOL Study Report MATL 301 Operations Planning MATL 804 ATCID 3. Responsibility MATL is an independent merchant transmission-only company based in Calgary, Alberta, Canada doing business in Canada as Montana Alberta Tie LTD and in the United States as MATL LLP, collectively referred to as MATL. MATL retains the responsibility of performing seasonal studies to determine its SOL in accordance with the Peak RC methodology for the operations horizon. 4. Long Term Capability MATL Path 83 is a 345 km, 240/230kV, 330 MVA transmission line designed for continuous power transfers of up to 325 MW north-to-south and 300 MW south-to-north metered at MATL 120S. Based on the Phase II Path Rating studies approved by the PRG and accepted by the WECC PCC, MATL Path 83 is able to achieve the following ratings metered at MATL 120S substation: Page 1 of 15
MATL Path 83 Transfer Direction North-to-south South-to-north MATL 120S 325 MW 300 MW MATL Path 83 southbound long term capability identified in the table above is contingent upon seasonally studying the limitation identified in section 5. 5. Limiting Conditions Conditions limiting the availability of MATL Path 83 transfer capability will be analyzed seasonally by determining the SOL in accordance with the Peak RC methodology for the operations horizon. Based on the seasonal studies reviewed by the NOPSG and submitted to the Peak RC, MATL Path 83 is able to achieve the following seasonal limits with all circuit equipment in service. As a result, any combination of operation within these maximum limits is acceptable under normal operating conditions. The SOL on MATL is adjusted in accordance with additional study work for conditions when MATL s equipment such as its series compensation at Hay Lake and Marias are out of service. Under certain import and export scenarios where the direction of the flows on WECC designated Path 1 and MATL Path 83 are in opposite direction with respect to Alberta s market, MATL s SOL may be reduced due to the Phase Shifting Transformer (PST) reaching its angle limit. Page 2 of 15
Imports into Alberta MATL SOL Northbound Maximum northbound flow at MATL 120S into the Alberta Interconnected Electric System (MW) Maximum northbound flow into Alberta at the CA-USA border (MW) AB.MT.MATL Maximum northbound flow at Great Falls into the MATL Interconnected System (MW) MATL.NWMT Normal Operations 300 310 1 325 Hay Lake and Marias series compensation out of service MATL radially connected to the NWMT system 248 254 1 266 N/A N/A 189 Imports into Montana MATL SOL Southbound Maximum southbound flow at MATL 120S into the MATL Interconnected System (MW) Maximum southbound flow into Montana at the CA-USA border (MW) AB.MT.MATL Maximum southbound flow at Great Falls into Montana (MW) MATL.NWMT Normal Operations 325 315 1 300 Hay Lake and Marias series compensation out of service MATL radially connected to the NWMT system 263 256 1 245 N/A N/A 189 5.1 Northbound Limit The studies identified that there is a limitation on the maximum simultaneous import into Alberta between Path 1 and MATL Path 83. However, the allocation of imports into Alberta will be determined by AESO as per their ATC and Transfer Path Management rule. The rule ensures that the total flow on Path 1 and MATL Path 83 is less than the sum of Path 1 and MATL Path 83 simultaneous limits. 1 For metered flows at CA-USA border as Balancing Authority boundary interchange between AESO and NWMT. Page 3 of 15
5.2 Southbound Limit For southbound flows into Montana at Great Falls, MATL Path 83 is able to achieve its full capability as documented in the WECC Path Rating studies unless real-time constraints necessitate curtailment. 5.3 North Terminal vs. Border POR/POD For Transmission Service requests under the MATL Tariff, the north terminal is the MATL 120S substation 240 kv bus near Lethbridge, Alberta. However, the POR/POD to be used for the MATL Line north end must be represented at the Canada-USA Border identified as a POR/POD with point name of AB.MT.MATL. This enables the Alberta portion of the MATL Line to be internalized within the AESO market and AESO Balancing Authority Area, which is in conformance with AESO procedures and Alberta governance. The Alberta portion of the MATL Line is further described in MATL 814 MATL Line Losses in Alberta procedure, posted on MATL s OASIS under the Business Practices folder. The ATC for the MATL Line is posted on under the System Data prompt. Sample diagrams of the MATL PORs/PODs are illustrated in Section 6 below. 6. ATC computation in the Scheduling Horizon MATL computes all scheduled energy flows and transmission service requests in its calculations to update its ATC in real-time. The sum of existing firm commitments along with Capacity Benefit Margin (CBM) and Transmission Reliability Margin (TRM) are subtracted from the Total Transfer Capability (TTC) to determine MATL s ATC at any given time during the Scheduling Horizon. All Transmission Service Requests (TSRs) and scheduled energy tags are attested against the ATC to decide if a request for a new TSR or the request to schedule energy will be approved or rejected. To determine the remaining ATC that would be available for new TSRs, MATL continuously and simultaneously decrements the TTC on each segment of the MATL Line for each confirmed and pending TSR. The same procedure is used to determine non-firm ATC, including the release of transmission capacity from unscheduled energy in the Scheduling Horizon. If the recalculated ATC is negative for either segment of the MATL Line, MATL s curtailment manager software will curtail schedules as necessary to restore ATC from a negative value. Page 4 of 15
6.1 Northbound Flow Example As depicted by the flows in Figure 1 below, MATL s firm ATC is 0 MW for a scenario where AESO s ATC into Alberta on MATL is 300 MW and existing firm commitment of 300 MW is in place between MATL and its customers. On the contrary, non-firm ATC is 61 MW as a result of unscheduled firm commitment released as non-firm capacity in the Scheduling Horizon. MATL 120S AESO ATC = 300 MW POD: AB.MT.MATL Canada/US Border MATL TTC = 300 MW MATL firm ATC = 0 MATL non-firm ATC = 61 MW 239 MW POR: WWA Hay Lake 189 MW (Firm) RimRock 50 MW (Firm) POR: MATL.NWMT Great Falls Figure 1: MATL's Northbound ATC in Scheduling Horizon Page 5 of 15
6.2 Southbound Flow Example As depicted by the flows in Figure 2 below, MATL s firm ATC is 200 MW for a scenario where the TTC into Montana on MATL is 300 MW and existing firm scheduled commitment of 100 MW is in place between MATL and its customers. Similarly, non-firm ATC is also 200 MW since there is no unscheduled firm commitment that can be released as non-firm capacity in the Scheduling Horizon. MATL 120S POR: AB.MT.MATL Canada/US Border 50 MW (Firm) POR: WWA Hay Lake 50 MW (Firm) RimRock 100 MW POD: MATL.NWMT Great Falls MATL TTC = 300 MW MATL Firm ATC = 200 MW MATL non-firm ATC = 200 MW NWE ATC = 300 MW Figure 2: MATL's Southbound ATC in Scheduling Horizon Page 6 of 15
7. Management of ATC and SOL on Path 83 MATL Line The POR/POD for MATL s north terminal is represented at the Canada-USA Border with point name of AB.MT.MATL. This POR/POD point also represents the interchange between the MATL and AESO system. Similarly, Path 83 MATL line south end terminal is represented at the Great Falls substation with point name of MATL.NWMT. The ATC values posted on these two terminals represents the transfer capability of the MATL line at any given time. As depicted in Figure 3, MATL manages these terminals to ensure that the path is not limited for the Hay Lake connected wind customer under scenarios when an external constraint is identified by either NWMT or AESO. When MATL is radially connected to the NWMT system, the POR/POD for MATL s north terminal is WWA. This POR/POD point represents the interconnection point for the Rim Rock wind facility. The POR/POD for MATL s south terminal is the Great Falls substation with point name of MATL.NWMT. The ATC values posted on these two terminals represents the transfer capability of the MATL line at any given time. When MATL is operated radially to the NWMT system, the ATC has been identified as 189 MW based on the maximum generation output from the Rim Rock facility. Technical studies have confirmed that MATL can operate safely and reliably in this operating configuration with this maximum loading level. When MATL is radially connected to the Alberta system, the POR/POD for MATL s north terminal is AB.MT.MATL. This POR/POD point also represents the interchange between the MATL and AESO system. The POR/POD for MATL s south terminal is WWA. The ATC values posted on these two terminals represents the transfer capability of the MATL line at any given time. When MATL is operated radially to the Alberta system, the ATC has been identified as 5 MW southbound and 0 MW northbound based on the maximum station service load at the Rim Rock facility. MATL can operate safely and reliably in this operating configuration with this maximum loading level. Page 7 of 15
AESO System Import ATC = AESO s Real-Time MATL System Export ATC = AESO s Real-Time POR/POD: AB.MT.MATL Canada/US Border Export ATC = AESO s Real-Time Import ATC = 325 MW POR/POD: WWA POD: MATL.WWA Hay Lake RimRock MATL System NWE System Export ATC = 325 MW POR/POD: MATL.NWMT Great Falls Import ATC = 325 MW Export ATC = 300 MW Import ATC = 300 MW Legend MATL AESO NWE Figure 3: Management of ATC and SOL on MATL Page 8 of 15
7.1 Southbound Constraint Identified by AESO MATL export ATC into Alberta at AB.MT.MATL is automatically adjusted by OATI s Curtailment Management software by utilizing real-time ATC values provided by the AESO. However, MATL s import ATC at the AESO end is set to 325 MW regardless of any constraints in the Alberta system. This ensures that the Hay Lake connected wind customer is not restricted to export southbound into Montana due to possible real-time constraints in Alberta. This is further illustrated in Figure 4 for a scenario when AESO s export ATC is 100 MW and MATL s export ATC is 325 MW into Montana. Page 9 of 15
AESO System Real Flows <= 100 MW Import ATC = AESO s Real-Time MATL System Export ATC = 100 MW POR/POD: AB.MT.MATL Canada/US Border Export ATC = AESO s Real-Time Import ATC = 325 MW POR/POD: WWA POD: MATL.WWA Hay Lake Real Flows = Maximum Capacity (189 MW) RimRock Real Flows <= 289 MW MATL System NWE System Export ATC = 325 MW POR/POD: MATL.NWMT Great Falls Import ATC = 325 MW Export ATC = 300 MW Import ATC = 300 MW Legend MATL AESO NWE Figure 4: Southbound Constraint Example Page 10 of 15
7.2 Northbound Constraint Identified by NWMT MATL export ATC into Montana at MATL.NWMT is set to 300 MW as per the SOL studies coordinated with NWMT. Similarly, the import ATC into MATL at the NWMT end is set to 325 MW regardless of any constraints in Montana system. This ensures that the Hay Lake connected wind customer is not restricted to export northbound into Alberta due to possible real-time constraints in Montana. This is further illustrated in Figure 5 for a scenario when NWMT s export ATC is 100 MW and MATL s import ATC is 325 MW northbound into Alberta. Note: MATL ATC posting does not ensure transmission capacity is available through adjacent scheduling segments. Page 11 of 15
AESO System Import ATC = AESO s Real-Time MATL System Export ATC = AESO s Real-Time POR/POD: AB.MT.MATL Canada/US Border Import ATC = AESO s Real-Time Export ATC = 325 MW Real Flows <= 289 MW POR/POD: WWA POD: MATL.WWA Hay Lake Real Flows = Maximum Capacity (189 MW) RimRock MATL System NWE System Export ATC = 100 MW POR/POD: MATL.NWMT Great Falls Import ATC = 325 MW Export ATC = 300 MW Import ATC = 300 MW Real Flows <= 100 MW Legend MATL AESO NWE Figure 5: Northbound Constraint Example Page 12 of 15
8. Definitions and Acronyms Unless the context otherwise indicates, any word or expression defined in the NERC Standards shall have that meaning when capitalized in this Operating Procedure. The following additional terms are capitalized in this Operating Procedure when used as defined below: Term AESO MATL NOPSG NWMT Peak RC PRG WECC WECC PCC Definition Alberta Electric System Operator Montana Alberta Tie Limited Northwest Operations Planning Study Group NorthWestern Energy Peak Reliability - Reliability Coordinator Project Review Group Western Electricity Coordinating Council WECC Planning Coordination Committee 9. Change Procedure for Operating Procedures MATL will update this document based on the seasonal SOL studies performed consistent with the Peak RC methodology. Page 13 of 15
Change History Version No Reason for Change Changed By Date 0.1 Prepared initial draft based on Path Rating and SOL study results. 1.1 Provide Great Falls terminal representation in provided tables. Aekam Sodhi 2013-06-10 Darrel Gunst 2013-06-25 1.2 Minor modifications to section 5. Aekam Sodhi 2013-07-02 1.3 Clarification of Purpose statement and footnotes. Added maximum flows at CA-USA border. 1.4 Added section 6 that describes the computation of ATC in the Scheduling Horizon. 1.4a Added Sec. 5.3 North Terminal vs. Border POR/POD. 1.5 Updated section 5 as per southbound SOL values confirmed by NorthWestern Energy. Removed footnotes 1 and 2 as requested by AESO. 1.6 Added section-7 on Management of ATC and SOL on Path 83 MATL Line. Darrel Gunst 2013-07-09 Aekam Sodhi 2013-07-26 Darrel Gunst 2013-07-30 Aekam Sodhi 2013-08-09 Aekam Sodhi 2013-12-05 1.7 Modifications to section 7. Kevin Burns Larry Monday 2013-12-19 1.8 Added note in section 7.2 as per NorthWestern Energy Aekam Sodhi 2014-07-24 Added language on real-time constraints in section 5.2 as per NWMT. 1.9 Updated SOL table to include scenario when MATL series compensation is out of service. Aekam Sodhi 2014-08-13 2.0 Included a description of MATL radially connected to the NWMT system, which is a new operating configuration for MATL, in sections 5 and 7. Michael Manarovici 2.1 Replaced WECC RC with Peak RC. Michael Manarovici 2015-04-02 2015-04-07 Page 14 of 15