NORTHERN TIER TRANSMISSION GROUP (NTTG) BIENNIAL TRANSMISSION PLAN. DRAFT SUMMARY REPORT - January 2013

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1 NORTHERN TIER TRANSMISSION GROUP (NTTG) BIENNIAL TRANSMISSION PLAN DRAFT SUMMARY REPORT - January 2013 Executive Summary: This report summarizes the findings of power flow studies to determine: 1) if there is adequate transmission capability within the existing Northern Tier Transmission Group (NTTG) system to meet the needs of the 2022 loads and resources; 2) whether the Common Core Transmission Assumptions (CCTA) provide enough transmission capacity to meet the 2022 needs under various stressed conditions with respect to the NTTG footprint; and 3) if a new direct current (DC) bipole transmission line from Wyoming to Nevada (TransWest Express) is adequate to move 3000 MW from the wind farms in Wyoming to the Nevada marketplace in the 2022 timeframe. The studies demonstrate that there is not adequate transmission capacity in the existing interconnected NTTG system to meet the needs of the forecasted 2022 loads and resources. Therefore, it is necessary to conduct regional studies to determine what additional transmission facilities are required in order to accommodate 2022 loads and resources under various stressed conditions relative to the NTTG footprint. The studies of five different stressed conditions illustrate that the CCTA transmission additions are adequate for all five NTTG conditions studied. The preliminary study results of the DC line scenario indicate that either additional transmission facilities or a significant amount of remedial action schemes (RAS) is required in order to mitigate significant impacts on the NTTG system. Introduction: The NTTG Biennial Transmission Plan is a result of a two-year study process to determine if adequate transmission has been planned over the next ten years to accommodate the loads and resources forecasted for the year 2022 and, if not, what additional transmission projects may be required. These forecasts were provided by NTTG stakeholders during the first quarter of the two-year process. The actual biennial transmission study consists of three parts: 1) the null case study; 2) five core case studies; and 3) a scenario study. All of these cases were derived from the 2022 TEPPC Production Cost model which was developed by the Western Electric Coordinating Council (WECC). The null case modified the NTTG Heavy Summer Core case by removing 23 of the 30 CCTA projects. The purpose of the null case study is to demonstrate the inadequacy of the transmission system if these projects were not built. Seven of the 30 CCTA projects were left in the case because they are either already in service or are expected to be in service within the planning cycle. The five core cases represent five different stressed conditions for the NTTG footprint. These cases include the Common Core Transmission Assumptions (CCTA) developed by WECC for the TEPPC model. These assumptions are composed of 30 new transmission projects that meet several criteria established by WECC to insure that the projects have a very high probability of actually being in service by the year Draft Biennial Transmission Plan 2/4/13 1

2 The scenario case is a modification of the NTTG Heavy Export Core case which represents a new 3000 MW wind resource in Wyoming that is delivered to the Las Vegas area via a new direct current (DC) bipole transmission line called the TransWest Express. This case is studied to determine if any additional transmission is required within the NTTG footprint for this scenario. The study process is described in the NTTG Revised Study Plan. This report summarizes the results of these three study efforts. Ten-Year Forecast: In quarter one of the two-year study process, stakeholders submitted loads, resources, and expected transmission additions for the next ten years. The following discussion is an excerpt from the study plan comparing the 2012 submittals to those in 2010 which led to the decision to proceed with the study process. 1. A set of loads was provided in response to the Q1 data request, consisting of forecasted area loads for Balancing Authority Areas internal to the Northern Tier footprint. These loads are generally those in the participating load serving entities official load forecasts (such as those in integrated resource plans) and are similar to those provided to the Load and Resource Subcommittee of the WECC Planning Coordination Committee. Loads will be expanded, where necessary, from forecasted peaks and averages to hourly loads for use in the securityconstrained economic commitment and dispatch programs. Table 1 below shows a load comparison from data submitted during Q1 of 2012 compared with loads that were in the 2010HS case used in the last NTTG planning cycle. PacifiCorp was the only one to submit any DSM numbers in both requests. The amount of incremental DSM in the ten-year forecast this cycle is 125 MW compared to 299 MW that was submitted last cycle. Contributing Utility Table 1 - Load Comparison between 2010 and 2012 Data Submittals 10yr Summer Load Data submitted in Q yr Summer Load in 2010 NTTG base case Difference Avista Basin Electric Black Hills Idaho Power NorthWestern PacifiCorp East PacifiCorp West Portland General TOTAL Draft Biennial Transmission Plan 2/4/13 2

3 2. Resources Resources provided in response to the Q1 data request are incremental to existing resources within the Northern Tier footprint and are summarized in Table 2a (2010 Q1 Data submittal) and Table 2b (2012 Q1 Data submittal). Resource data comes from integrated resource plans, interconnection queues, resource developers, and transmission providers who provide indications of expected resource additions. Table 2a: Resource Additions Identified in 2010 Q1 Data Submittals Q1 RESOURCE DATA SUMMARY Resources added by 2020 (MW Capacity) From 2010 Q1 Data Response Contributing Utility Natural Gas Wind Geothermal Hydro- Electric Coal Market TOTAL Basin Electric Grasslands Renewable Energy Idaho Power NorthWestern PacifiCorp PCW PGE Transwest Express Transcanada Chinook/Zephyr TOTAL Draft Biennial Transmission Plan 2/4/13 3

4 Table2b: Resource Additions Identified in 2012 Q1 Data Submittals Q1 RESOURCE DATA SUMMARY Resources added by 2021 (MW Capacity) From 2012 Q1 Data Response Contributing Utility Natural Gas Wind Solar Biomass Oil Geothermal Hydro- Electric Coal Market TOTAL Avista Black Hills (IRP) Idaho Power NorthWestern PacifiCorp PCW PGE TOTAL Transmission A number of specific transmission projects were identified in response to the Q1 data request. Table 3, below, summarizes the submitted transmission projects. The table also denotes if a transmission project was submitted in the previous biennial cycle. Draft Biennial Transmission Plan 2/4/13 4

5 Table 3: Transmission Projects Identified in 2012 Q1 Data Submittal * indicates that this facility was included in the last cycle Utility Voltage Project Black Hills 230 kv Teckla-Osage-Lange [WY] Idaho Power Co. 500 kv *Boardman-Hemingway [ID-OR] 500 kv *Gateway West (with PacifiCorp) [WY-ID] NorthWestern Energy 500 kv *MSTI Project [MT-ID] 500 kv *Montana Intertie (Path 8) Upgrade [MT-WA] 230 kv *AMPS line (Path 18) Upgrade [MT-ID] 230 kv *MSTI Collector (up to 5 segments) [MT] PacifiCorp 500 kv *Gateway Central [ID-UT] 500 kv *Gateway South [WY-UT] 500 kv *Gateway West (with Idaho Power) [WY-ID] 500 kv *Hemingway-Captain Jack [ID-OR] 230 kv *Walla Walla-McNary [WA-OR] Portland General 500 kv *Cascade Crossing (Boardman-Salem) [OR] 230 kv Horizon-Keeler [OR] 230 kv Blue Lake-Gresham [OR] 230 kv Pearl-Sherwood [OR] TransWest Express 600 kv *DC line [WY-NV] Facilities from Last Cycle not submitted in current cycle: Grasslands Renewable 230 kv Collector System [MT] 500 kv DC line, Colstrip to Bismarck {MT-ND] TransCanada 500 kv Chinook Project (AC+DC) [MT-ID-NV] 500 kv Zephyr Project (AC+DC) [WY-ID-NV] 4. Q1 Data Submittal Comparison Conclusions: The comparison tables show that although load growth has slowed in some areas, there is still a significant increase in load since the last ten-year forecast. However, the amount of new resources submitted in the current cycle is down significantly (9000 MW w/o DSM). Of this amount, 7600 MW of the reduction is wind generation, where 3000 MW was double-counted in the last cycle and 3000 MW from the TransCanada project was not submitted this cycle. Northwestern reduced their latest resource forecast by 2647 MW to represent only committed projects. Another 350 MW of resource went away with the Grasslands Renewable Energy project. Basin Electric s coal plant (385 MW) submitted last cycle is now in service. Draft Biennial Transmission Plan 2/4/13 5

6 Compilation of Base Cases: The base cases used in the biennial study process were all derived from the TEPPC 2022 production cost model (PC0). This model includes forecasted loads and resources for the year 2022 that were submitted to the WECC Loads and Resources committee from all transmission providers in the interconnected system. The TEPPC model also includes future transmission additions from the Common Core Transmission Assumptions (CCTA) which were approved by TEPPC as meeting the requirements for projects that have a high likelihood of being in service by Members of the NTTG Technical Work Group (TWG), representing the entities who submitted data in Q1, approved the use of the data from the TEPPC 2022 model as adequately representing what was submitted in Q1. The NTTG TWG determined that the TEPPC model hourly data should be analyzed in order to identify five different stressed conditions relative to the NTTG footprint. Data from the five stressed conditions would then be exported and used in the creation of five core base cases. The five stressed conditions identified by the TWG and approved by the Planning Committee were: 1) heavy NTTG summer load conditions; 2) heavy NTTG winter load conditions; 3) maximum NTTG export conditions; 4) maximum NTTG import conditions; and 5) maximum combined flow on Pacific Intertie lines (California-Oregon Intertie and Pacific DC Intertie). The TEPPC analysis resulted in the following hours for the five stressed conditions listed above respectively: 1) July 21, 1600 hrs; 2) January 5, 800 hrs; 3) November 6, 1000 hrs; 4) September 8, 1700 hrs; and 5) June 6, 1200 hrs. Some manipulation of the generation dispatch and loads was done to achieve the desired stressed conditions with generators operating within proper limits. These five core cases were then reviewed and approved by members of the TWG. In addition to the five core cases, two other base cases were created the null case and the TransWest Express scenario case. Study Methodology: Once acceptable base cases were prepared for the null case and all of the core cases, the cases were analyzed to make sure that they met all of the WECC and NERC reliability criteria for steady state (N-0) conditions. These acceptable cases were then used to perform a power flow contingency analysis with approximately 420 single element outages. The contingency analysis was also an iterative process where initial results showed the need to update remedial actions to be taken during certain contingencies. The reported violations from this analysis were then carefully analyzed by the study team to separate out any violations that showed up on non-load buses, especially series capacitor buses. There were also some violations that occurred at local radial and low-voltage (<100 kv) buses that were eliminated as non-legitimate violations. Specific transmission fixes were not studied for the null case as this case was only to confirm that today s NTTG transmission system is not adequate to meet the requirements of the forecasted 2022 loads and resources. The core cases have 23 additional transmission projects (CCTA) included which provide additional transmission support for the year These cases were tested to determine if any additional transmission upgrades are needed in the next ten years. 1 TEPPC CCTA report is included in appendix. Draft Biennial Transmission Plan 2/4/13 6

7 Null Case Results: As mentioned earlier, the null case represents 2022 loads and resources being served with the present NTTG transmission system (including 7 CCTA projects as explained above). Therefore it is not surprising that there are performance violations even in the base case (N-0). These violations consist of two high voltage violations on buses in Alberta (outside NTTG footprint), 13 branch overloads, and one path interface where the flow exceeds the path rating (Path 18). Also, as expected, the contingency analysis resulted in many legitimate violations during outage conditions. Table 4 below shows these null case results along with the NTTG summer core case as a comparison. NTTG Heavy Summer Core Case Results: This case represents the maximum NTTG summer peak 2022 condition of 23,846 MW. The net NTTG export is minimal (1370 MW) in the case since most of the NTTG internal generation is utilized to serve the peak NTTG load. As mentioned earlier, this case, along with all other core cases, contains all 30 of the CCTA projects. With these additions, there were still a few base case (N-0) violations, two high voltage buses and two branch overloads but all were outside of the NTTG footprint and of no consequence to the study. The power flow contingency analysis resulted in several reported violations, but all were determined to be acceptable. Table 4 presents the results of the power flow contingency analysis along with a comparison to the results of the null case. Table 4: Comparison of Summer Core Case Results with Null Case Results Results of 23 Projects Removed Summer Core Case *3 Null Case Branch Amp 0 37 Branch MVA 4 79 Bus High Volts 8 17 Change Bus High Volts Bus Low Volts 0 56 *2 Change Bus Low Volts 90 -Acceptable Unacceptable *1 *1 Voltage Deviation are > 5% and the voltage falls below 0.9 *2 All the voltages are below 0.9 *3 Everything under Case 0 is acceptable Draft Biennial Transmission Plan 2/4/13 7

8 NTTG Heavy Winter Core Case Results: This case represents the NTTG peak winter load conditions of 20,280 MW. Again most of the NTTG generation is used for serving NTTG loads with only 731 MW of net export. With the help of the CCTA projects in the case, there were only 3 violations in the base case (N-0) which were outside of the NTTG footprint area on step-up transformers of no consequence to the study. Although several reported violations resulted from the contingency analysis, all of the reported violations were investigated by the study team and all were determined to be acceptable. NTTG Maximum Export Core Case Results: This case was modified from the original TEPPC data to maximize the NTTG export to a total of 10,077 MW. As with the other core cases, this case also contains the 30 CCTA projects and represents a low NTTG load condition (11,970 MW) with high internal generation. The base case power flow (N-0) had a few high voltage violations reported but all were non-load buses on series capacitors. There were no branch overloads. The contingency analysis showed some reported violations, but all were examined and determined to be acceptable. NTTG Import Core Case Results: This case was finalized with a net NTTG import of 81 MW and also includes the CCTA projects. As might be expected in this case, the net NTTG load is fairly high (20,086 MW) with reduced internal generation, thus producing an import condition. The base case (N-0) conditions are acceptable with just two transformers outside of the NTTG footprint loaded at their limits (no significance to study). The contingency analysis resulted in several reported violations which turned out to be acceptable upon further examination. High COI and PDCI Core Case Results: This case was studied to look at fairly heavy flow conditions on the Pacific Intertie lines (4562 MW on COI and 2946 MW on the DC lines) with relatively low NTTG export (3290 MW). As with all of the core cases, this one also includes the 30 CCTA projects. There were no N-0 violations in this case. The N-1 contingency analysis resulted in several reported violations which were determined to be acceptable upon further investigation. TransWest Express Scenario Results: These studies are underway but the results have not been completely analyzed. Preliminary results show the need for remedial actions for loss of either one or two poles of the new DC line. Further studies will be needed to determine the extent of these remedial actions. The final results will be added to this report when completed during Q5. Draft Biennial Transmission Plan 2/4/13 8

9 Conclusions: 1. The results of the null case demonstrate that the existing NTTG transmission system, without 23 of the 30 CCTA projects, there is not adequate transmission capacity to meet the 2022 load and resource requirements. 2. The results of the five core cases demonstrate that with the CCTA projects added there is adequate transmission to accommodate the 2022 loads and resources. No additional transmission facilities are needed in this time frame based on the analysis of the five stressed conditions represented in the core cases. 3. Preliminary results show the need for remedial actions for loss of the new DC line in the TransWest Express 3000 MW scenario. Draft Biennial Transmission Plan 2/4/13 9