2013 Economic Study Report

Transcription

1 2013 Economic Study Report PPL EnergyPlus, LLC December 19, 2013 Electric Transmission Planning

2 Table of Contents Executive Summary... 3 Study Constraints and Conditions... 4 Study Parameters... 5 Steady-State Power Flow Analysis... 6 Results... 7 Conclusions... 8 Required Mitigation... 8 Attachments... 8 Attachments... 9 Attachment A Economic Study Requests... 9 Attachment B Economic Study Plan

3 Executive Summary NorthWestern Energy ( NWE ) has completed the Economic Congestion Study ( ECS) for PPL- MT. In 2013, NWE received three valid local ECS requests - two from PPL and one from another stakeholder. The two PPL requests are provided in Attachment A. After input from NWE s Transmission Advisory Committee that included PPL, NWE made a determination that a more efficient way to study the original two requests would be to revise the two requests into northbound and southbound transmission flow studies. The northbound flow into Great Falls was accepted as a 2013 ECS request. The northbound flow request was to identify congestion on the existing south of Great Falls transmission lines 1 under extreme winter weather and operating conditions. The study investigated whether congestion might occur using certain assumptions for generation, load and transmission topology as describe further below. The Study Plan for the approved ESR is provided as Attachment B. The goal of the ECS is to identify whether northbound flow congestion on the transmission lines south of Great Falls may occur under extreme conditions. This congestion may cause certain reliability criteria thresholds to be exceeded, thus limiting northbound flows. For the purpose of this study the northbound flows were increased by simultaneously increasing Great Falls area load (including the northbound flow on MATL through Great Falls), reducing Great Falls hydro, turning off all north of Great Falls and Judith Gap area wind generation and increase generation in the southern part of Montana. Several options for alleviating the congestion were studied, the most cost effective being shunt capacitors on certain 100 kv lines that are south of Great Falls. Under current outage conditions and Great Falls area extremely high loading the transmission system may overload but normal relay protection corrects the overload conditions without loss of load. After applying the ECS generation dispatch pattern it was found that some low voltage issues may arise under certain N-1 conditions that can be resolved with additional shunt capacitance on certain 100 kv lines. The results of this ECS study are informational only and do not obligate NWE to construct or commit to construct the studied projects nor does the study assign cost responsibility for any investments or otherwise determine whether any project should be implemented within NWE s local area transmission plan. The ECS does, however, inform NWE s local area transmission plan. 1 Existing south of Great Falls transmission lines include two 230 kv lines and five 100 kv lines. 3

4 Study Constraints and Conditions The purpose of this study was to determine the constraints on the south of Great Falls transmission lines that might occur during an extreme winter day. The study used a WECC 2014 Heavy Winter case and assumed very low Great Falls hydro due to icing on the river, no wind generation, normal winter operations for the Helena hydro, high exports to WAPA, and MATL northbound interchange varied from 0 MW to the maximum of 325 MW (measured at Great Falls 230 kv switchyard), Dave Gates generation was turned off, most other generators at maximum, and imports, if required, from Path 8. Study Assumptions The initial Base Case is heavy winter load. Load o Heavy Winter - Extreme Cold day o Great Falls area load peak = 238 MW o Helena area load high o Load in Alberta high Generation o Calm (no or very little wind) - resulting in Judith Gap & Glacier Wind I & II generation at 0 MW o Freezing on river resulting in very low hydro generation (50 MW) MW distributed between all hydro generators in Great Falls o Southern MT & Dave Gates (gas) generation assumed not available. o Ft Peck at minimum o Helena generation - unchanged from base case o All other generation dispatched at levels to match generation to load (generation including Colstrip, Corette, etc.) MATL o Phase shifter pushing from 0 MW to 325 MW northbound (measured at Great Falls 230 kv switchyard) Congestion, if any, was mitigated by adding shunt capacitors. 4

5 Study Parameters NWE utilized PSS/E software to simulate the proposed economic study. All studies were conducted through a steady state power-flow analysis only. This study used a 2014 Heavy Winter WECC base case with the addition of the Spion Kop and Musselshell wind farms. Also, MATL was modeled incorrectly in the WECC case so the correct model was inserted. 5

6 Steady-State Power Flow Analysis The scenario set forth in this ECS request was studied extensively under the ECS conditions as well as with proposed mitigation, if required. Per the ECS request, NWE studied the feasibility of adding a new 230 kv line going south out of Great Falls but found that shunt capacitors on certain 100 kv lines were equally effective with much lower cost. 6

7 Results Under the ECS conditions the study found that the loss of a portion of the Great Falls to Broadview 230 kv line may cause one or more 100 kv lines to overload and normal line relaying may open to protect the line with no load loss. In the event of an outage from Highwood Tap to Judith Gap to Judith Gap South that also takes out the kv Auto due to breaker placement, low voltages on the 100 kv line between Judith Gap and Raynesford may be observed under the proposed extreme high loads and 0 MW and MVar wind generation without mitigation. This may result in some limitation to path flows to ensure the reliability of the system. Two mitigation options were evaluated. The first mitigation was to install a 5 MVAR shunt capacitor bank at Straw and a 15 MVAR shunt capacitor bank at Utica. The second was to assume construction of a new 230 kv line similar to the customer s request. However, the two shunt capacitor banks are much more cost effective than a new line. A very high level estimate of the cap banks is approximately $500,000 and a new line is approximately $100 million. Table 1 summarizes the power flow study results. This table show three rows representing the existing transmission system under different load profiles. 1) The first row shows that the assumptions of this ECS request increase the SOGF path flows by 216 MW above the TTC to 556 MW. The loading under this scenario includes the 238 MW of load in Great Falls, 36 MW export to the Highline, and 328 MW export to MATL for a total area load of 605 MW. Under N-0 conditions there are no problems. Many N-1 outages were considered but the critical outage is the 230 kv line between Highwood tap and Judith Gap south which also takes with it the kv Autotransformer. After protective relaying clears any thermal overloads, no loads are lost but voltages as low as 0.78 pu are observed on the 100 kv line between Judith Gap and North Raynesford. 2) The second row shows the results of limiting the SOFG flows to 343 MW, just over the TTC by reducing the flows on MATL to 136 MW for a total area load of 413 MW. Protective relaying clears any overloads and the voltages remain within allowable limits without loss of load. 3) The third row shows the effect of adding Shunt Capacitors to solve the voltage problems. The MATL flows were returned to maximum of 327 MW bringing the total area load back up to 604 MW and returning the SOGF flows to 553 MW. 20 MVAR of shunts - strategically placed on the 100 kv line between Judith Gap and North Raynesford - will mitigate the voltage violations. Again protective relaying clears any overloads and no load is lost. Existing Transmission under ECS Assumptions Existing Transmission under ECS Assumptions With Shunt Caps strategically placed on the 100 kv lines south of Great Falls Table 1: 2013 ECS with Extreme Winter Hydro and Load Conditions Great Falls Flows Great area Load + Steady State Outage State and Most Critical on the MATL Falls WAPA and Overloads and Outage Description SOGF Flows Hydro MATL Load Loss lines exports 7 Steady State Voltage Violations N MW 50 MW 328 MW 605 MW None none N-1: The loss of the 230 kv line Voltages as low as 0.78 from Highwood Tap to Judith Gap 475 MW 50 MW 234 MW 511 MW None from Judith Gap to South including the kv North Raynsford Auto at Judith Gap N MW 50 MW 136 MW 413 MW None None N-1: The loss of the 230 kv line from Highwood Tap to Judith Gap 292 MW 50 MW 76 MW South including the kv 353 MW None Auto at Judith Gap N MW 50 MW 327 MW 604 MW None None N-1: The loss of the 230 kv line from Highwood Tap to Judith Gap South including the kv Auto at Judith Gap 497 MW 50 MW 199 MW 476 MW None None Voltages right at the acceptable limit (0.902)

8 Conclusions The addition of shunt capacitor banks would resolve all issues presented by the ECS assumptions. However, with a slight wind in the area, the wind generation would provide sufficient voltage control to eliminate the low voltage. Required Mitigation No mitigation is required aside from the normal line relaying which is already in place. Attachments Attachment 1: The original PPL Economic Study Request Attachment 2: The agreed upon Economic Study Plan 8

9 Attachments Attachment A Economic Study Requests Instructions: Provide the information in the yellowed boxes. If the information is not available or unknown, please state so. Transmission Customers requesting an economic study shall, upon request of the Transmission Provider, supply all relevant information necessary to perform the economic study. If the Transmission Customer fails to provide the information requested, the Transmission Provider shall have no obligation to complete the study. By Signing this form you are certifying that this request is not for a single transmission service request or generation interconnection request. When form has been completed, please to: Kathleen Bauer at NorthWestern Energy (kathleen.bauer@northwestern.com. If you have questions about filling out this form, please contact John Leland at NorthWestern Energy (john.leland@northwestern.com. Study Request Control # (Assigned by Transmission Provider) Request for Economic Planning Study Study Sponsor Information: Date: Requesting Customer Name: PPL EnergyPlus, LLC Address: 45 Basin Creek Road State & Zip: Butte, MT Requestor: Jon Williamson Title: EMT Principal Analyst Phone Number: (406) jswilliamson@pplweb.com Are you an Eligible Customer Y/N: Yes Do you have a Current Service Contract: Yes 28-Feb-13 Transmission Provider: Utility Name: NorthWestern Energy In care of: Donald Bauer Title: Manager, Planning and Capacity - West Street Address 40 East Broadway City, State, Zip: Butte, MT Phone: (406) don.bauer@northwestern.com Study Request Details (1): 1 General Information: 2 Study Name: South of Great Falls Congestion Project (Minimum) 3 Projected In-service Date: Unknown 4 5 Narrative Description: Justification (2): 6 Study Location POR: Great Falls 230 kv Switchyard 7 Study Point of Delivery POD: Three Rivers Switchyard 8 MW Size: 9 Monthly or Hourly Amount MW (4): n/a 10 Monthly Energy amount MWH: n/a 11 Attach a Map of the study elements: Plese see attached pdf file. 12 Transmission Affected (4): 13 Any gathering Transmission: TBD 14 Conductor size (5): TBD 15 Bundled: TBD 16 Line spacing: TBD 17 L-L Voltage: 230 kv 18 Length (miles): TBD 19 Electric characteristic data (R, X): TBD TBD (sufficient to accommodate existing contractual and tariff obligations, including network and native load growth.) 20 Capital Cost ($/mile): Internal system reliability study. 21 Affected or Proposed Generation (3)(5): 22 Generator #1 Generator #2 23 Generator Name: Existing interconnected generation and generation with signed 24 Size: interconnection agreements. 25 Type: 26 Fuel type (Primary, Secondary): 27 Fuel cost ($/mmbtu): 28 Incremental Heat Rate Curve: N/A 29 Ramp Rate: 30 Min up time (hours): 31 Min down time (hours): 32 Generator Forced Outage Rate: 33 Start up cost: 34 Addional Load Integration 35 Load #1 Load #2 36 Load Name: NWMT Native and Network Load. Off system loads served by LTF PTP TSRs. 37 MW Size: Current and projected obligations. Current obligations. Location: NWMT Balancing Area NWMT Tie-line PODs and PORs 38 Hourly Profile (daily or monthly) MW: 39 Controlable Demand Side Resource Daily or Monthly Hourly Profile (MW) The purpose of the South of Great Falls (SOGF) Economic Study Request is a reliability study to relieve potential congestion between the Great Falls Area and the rest of the NorthWestern Energy Transmission System in both the Northbound and Southbound directions. Unless TP has other recommended approaches, this project would consist of a 230 kv line connecting Great Falls to Helena to Townsend to Three Rivers. The project could potentially use existing 100 kv line ROW. Thus, existing and future load and resource needs would be addressed while enhancing system reliability. The reliability study SOGF Project is a necessary response to congestion created by numerous generation interconnections and the impact of the Montana Alberta Tie Line (MATL). The SOGF Project is expected to reduce transmission congestion within the state of Montana, thereby allowing previously existing generation and newly interconnected generation to be moved to load within Montana while enhancing system reliability. By signing and submitting this request the requestor agrees to provide, to the greatest extent practical, additional information and agrees to cooperate as necessary to complete the economic study. Authorized Signature: Jon Williamson Date: 2/28/2013 Footnotes 1. Expand or add new cells (row or column) if additional space is needed. 2. Justification must include relevant facts and circumstances as addressed in Paragraph 549, FERC Order 890, OATT Reform. The justification should address all relevant facts that indicate that the study is for the purposes of planning for the alleviation of congestion through integration of new supply and demand resource into the regional transmission grid or expand the regional transmission grid in a manner that can benefit large numbers of customers, such as by evaluating transmission upgrades necessary to connect major new areas of generation resource (such as areas that support substantial wind generation). Specific requests for service would continue to be studied pursuant to existing pro forma OATT processes." Detailed impedance and other modeling data may be require to model the project 5. This planning process does not replace the System Impact Study process. Specific transmission service or generation interconnection will continue to be studied pursuant to existing proforma OATT processes. An Economic Planning Study request may not be used for a single transmission service request or generation interconnection request. For an Economic Study detailed generation cost data and hourly Load profile data is required. This will include the incremental dispatch cost, the startup cost, any startup constraints, the heat rate characteristics, any energy limitations. For wind generation, monthly peak and energy and hourly energy shapes for the entire year will be needed. If the requestor s own generation is affected by the request, the following information must be provided: economic dispatch costs, hourly generation patterns, relevant maintenance information; expected generation forced outage rate; and all other factors affecting generation output.

10 Instructions: Provide the information in the yellowed boxes. If the information is not available or unknown, please state so. Transmission Customers requesting an economic study shall, upon request of the Transmission Provider, supply all relevant information necessary to perform the economic study. If the Transmission Customer fails to provide the information requested, the Transmission Provider shall have no obligation to complete the study. By Signing this form you are certifying that this request is not for a single transmission service request or generation interconnection request. When form has been completed, please to: Kathleen Bauer at NorthWestern Energy (kathleen.bauer@northwestern.com. If you have questions about filling out this form, please contact John Leland at NorthWestern Energy (john.leland@northwestern.com. Study Request Control # (Assigned by Transmission Provider) Request for Economic Planning Study Study Sponsor Information: Date: Requesting Customer Name: PPL EnergyPlus, LLC Address: 45 Basin Creek Road State & Zip: Butte, MT Requestor: Jon Williamson Title: EMT Principal Analyst Phone Number: (406) jswilliamson@pplweb.com Are you an Eligible Customer Y/N: Yes Do you have a Current Service Contract: Yes 28-Feb-13 Transmission Provider: Utility Name: NorthWestern Energy In care of: Donald Bauer Title: Manager, Planning and Capacity - West Street Address 40 East Broadway City, State, Zip: Butte, MT Phone: (406) don.bauer@northwestern.com Study Request Details (1): 1 General Information: 2 Study Name: South of Great Falls Congestion Project (Robust) 3 Projected In-service Date: Unknown 4 5 Narrative Description: Justification (2): 6 Study Location POR: Great Falls 230 kv Switchyard 7 8 Study Point of Delivery POD: MW Size: 9 Monthly or Hourly Amount MW (4): n/a 10 Monthly Energy amount MWH: n/a 11 Attach a Map of the study elements: Plese see attached pdf file. 12 Transmission Affected (4): 13 Any gathering Transmission: TBD 14 Conductor size (5): TBD 15 Bundled: TBD 16 Line spacing: TBD 17 L-L Voltage: 230 kv 18 Length (miles): TBD 19 Electric characteristic data (R, X): TBD Anaconda Mill Creek 230 kv Switchyard and Broadview Switchyard TBD (sufficient to accommodate existing contractual and tariff obligations, including network and native load growth.) 20 Capital Cost ($/mile): Internal system reliability study. 21 Affected or Proposed Generation (3)(5): 22 Generator #1 Generator #2 23 Generator Name: Existing interconnected generation and generation with signed 24 Size: interconnection agreements. 25 Type: 26 Fuel type (Primary, Secondary): 27 Fuel cost ($/mmbtu): 28 Incremental Heat Rate Curve: 29 Ramp Rate: 30 Min up time (hours): 31 Min down time (hours): 32 Generator Forced Outage Rate: 33 Start up cost: 34 Addional Load Integration 35 Load #1 Load #2 36 Load Name: NWMT Native and Network Load. Off system loads served by LTF PTP TSRs. 37 MW Size: Current and projected obligations. Current obligations. Location: NWMT Balancing Area NWMT Tie-line PODs and PORs. 38 Hourly Profile (daily or monthly) MW: 39 Controlable Demand Side Resource Daily or Monthly Hourly Profile (MW) The purpose of the South of Great Falls (SOGF) Economic Study Request is a reliability study to relieve potential congestion between the Great Falls Area and the rest of the NorthWestern Energy Transmission System in both the Northbound and Southbound directions. Unless TP has other recommended approaches, this project would form a triangle of 230 kv lines connecting Great Falls to Anaconda, Great Falls to Billings, and Broadview-Billings to Anaconda. The Great Falls to Anaconda and Great Falls to Billings sections could potentially use existing 100 kv line ROW. If necessary, the existing Billings to Anaconda 230 kv line section could potentially be converted to a double circuit line. This new 230 kv triangle loop is expected to add significant new internal transfer capability and increase system reliability. Thus, existing and future load and resource needs within Montana would be addressed while enhancing system reliability. The reliability study SOGF Project is a necessary response to potential congestion created by numerous generation interconnections and the impact of the Montana Alberta Tie Line (MATL). The SOGF Project is expected to reduce transmission congestion within the state of Montana, thereby allowing previously existing generation and newly interconnected generation to be moved to load within Montana while enhancing system reliability. By signing and submitting this request the requestor agrees to provide, to the greatest extent practical, additional information and agrees to cooperate as necessary to complete the economic study. Authorized Signature: Jon Williamson Date: 2/28/2013 Footnotes 1. Expand or add new cells (row or column) if additional space is needed. 2. Justification must include relevant facts and circumstances as addressed in Paragraph 549, FERC Order 890, OATT Reform. The justification should address all relevant facts that indicate that the study is for the purposes of planning for the alleviation of congestion through integration of new supply and demand resource into the regional transmission grid or expand the regional transmission grid in a manner that can benefit large numbers of customers, such as by evaluating transmission upgrades necessary to connect major new areas of generation resource (such as areas that support substantial wind generation). Specific requests for service would continue to be studied pursuant to existing pro forma OATT processes." Detailed impedance and other modeling data may be require to model the project 5. This planning process does not replace the System Impact Study process. Specific transmission service or generation interconnection will continue to be studied pursuant to existing proforma OATT processes. An Economic Planning Study request may not be used for a single transmission service request or generation interconnection request. For an Economic Study detailed generation cost data and hourly Load profile data is required. This will include the incremental dispatch cost, the startup cost, any startup constraints, the heat rate characteristics, any energy limitations. For wind generation, monthly peak and energy and hourly energy shapes for the entire year will be needed. If the requestor s own generation is affected by the request, the following information must be provided: economic dispatch costs, hourly generation patterns, relevant maintenance information; expected generation forced outage rate; and all other factors affecting generation output. 10

11 Attachment B Economic Study Plan Draft 2013 Economic Congestion Study Request 2013 Study Plan for PPL Local Congestion Study Request Introduction During January and February of each year, NWE receives stakeholders Economic Congestion Study requests. In March, with input from NWE s Transmission Advisory Committee ( TRANSAC ), NWE made a determination whether each request was a valid request and classified each request as a local, regional or inter-connection wide request. Regional and interconnection-wide requests are forwarded to the Northern Tier Transmission Group ( NTTG ) and the Western Electric Coordinating Council ( WECC ), respectively. Pursuant to NWE s Attachment K, NWE may conduct up to two local economic congestion studies per year and if appropriate, study requests can be clustered into on study. In 2013, NWE received three valid local planning requests including the one described herein from PPL to identify congestion on the transmission lines south of Great Falls while moving power northbound across these lines. The study will investigate if congestion might occur using certain assumptions for generation, load and transmission topology as describe further below. During the March 7 TRANSAC meeting, it was decided this request was a valid request and would be evaluated as individual local economic study. This economic study plan will describe the study assumptions for the PPL economic congestion study request. The economic congestion study request from PPL is provided in Attachment A. From prior generation interconnection studies, congestion on the transmission lines south of Great Falls will likely occur after a certain amount of additional northbound flows, thus limiting northbound flows. The purpose of this study plan is to describe the assumptions that will increase the northbound flows by simultaneously increasing Great Falls area load (including MATL northbound load), reducing Great Falls area generation and increasing generation in the southern part of Montana. Study Assumptions The initial Base Case Study to be utilized is heavy winter load. Load o Heavy Winter - Extreme Cold day o Great Falls area load peak ~250 MW o Helena area load high o Load in Alberta high Generation o Calm (no or very little wind) - resulting in Judith Gap & Glacier Wind I & II generation at 0 MW (or very little) o Freezing on river resulting in very low hydro generation (50-60 MW max output) MW distributed between all hydro generators in Great Falls o Southern MT & Dave Gates (gas) assumed not available. o Ft Peck at minimum o Helena generation - do not change from base case o All other generation dispatched at levels to match generation to load (generation including Colstrip, Corette, etc.) MATL

12 o Phase shifter pushing 300 MW northbound Reliability Study Technique A power flow study of N-0, N-1 & Credible N-2 (if any) outages on the lines south of Great Falls will be taken. Identify the congestion and determine how much additional northbound flows (above the Base Case northbound flow) can be achieved before voltage and/or thermal problems first occur. Study Schedule: The NWE study schedule calls for economic study requests to be completed by the end of the year. If this study cannot be completed within the specified study time, NWE will inform the customer in writing of the delay, the reason for the delay, and an estimated time for completion 2. Base Cases: The Heavy Winter (2014HW) base case will be utilized. No new generation beyond the active Generation Queue of today (May 2013) will be added to the system. Study Methodology: 1. As stated above, a 2014 heavy load case will begin the study process. 2. Generation as requested in the study request will be adjusted in the Great Falls area. 3. South of Great Falls transmission system flows will be increased using Great Falls area load increases, MATL northbound flows increases, low existing generation in Great Falls area and increases to generation in the southern part of Montana. 4. A power flow study of N-0, N-1 & Credible N-2 (if any) outages on transmission lines south of Great Falls. 5. Increasing northbound flows will continue until reliability problem is encountered. Study Criteria: The study results will be evaluated based on the NERC and WECC performance criteria. Study Report: NWE will analyze the transmission system performance results and prepare a report of the conclusions. 2 Attachment K Business Practice, FERC Order 890, NWE Local Transmission Planning Attachment K, (NWE Economic Planning Study Timeline and Process). 12