2023

10-Year
Assessment

Generation interconnections

The size and location of new or expanded power plants can have significant impacts on the transmission system. These impacts are evaluated in MISO Definitive Planning Phase (DPP) process.  Information on the status, as of October 09, 2023, of generation requests in the ATC portion of the MISO generation interconnection queue is provided in this section. There continues to be significant activity in ATC’s footprint, ranging from newly proposed generation projects to cancellation of previously proposed generation projects.

There are two key aspects in determining the total impacts a proposed new generator may have on the transmission system:

  • impacts of interconnecting the new generator to the transmission system and 
  • impacts of using the transmission system to deliver power from the new generator. 

As described in MISO’s Attachment X process, a generator interconnection study is performed in three phases which are all within the Definitive Planning Phase (DPP): an Interconnection System Impact Study (Phase 1, 2 and 3), and an Interconnection Customer Interconnection Facilities Study (Phase 2 and 3). The Network Upgrade Facilities Study begins after the System Impact Study is completed in Phase 3.

The Interconnection System Impact Study includes a determination of whether the proposed generator and other nearby generators will remain connected to the system under various disturbance situations, such as line trips and equipment failures and includes a fault duty analysis to determine whether existing system equipment can accommodate the increased short circuit fault duty caused by the new generator. Additionally, the System Impact Study will identify solutions for any thermal, stability or fault duty deficiencies.

Delivery impacts are assessed during the DPP portion of the interconnection study process using the MISO deliverability methodology, which determines whether the output of a new generator is deliverable to the MISO energy market and to what percent if not wholly deliverable. Whatever portion of the new generator that is deliverable may then be used as a Network Resource by Network Customers through MISO’s Module E Resource Adequacy procedures.

The Interconnection Customer Interconnection Facilities Study is conducted in Phase 2 and 3.  It specifies and estimates the time and cost of the equipment, engineering, procurement, and construction of the interconnection facility upgrades identified in the earlier interconnection studies.

The Network Upgrade Facilities Study is conducted after Phase 3. It specifies and estimates the time and cost of the equipment, engineering, procurement and construction of the network system upgrades identified in the earlier interconnection studies.

The results of the interconnection studies are needed to develop a comprehensive picture of the transmission facilities that will be required for a proposed generator. Only transmission facilities that result from generators with a signed Interconnection Agreement are included in the 10-Year Assessment models.

The first portion of this section provides the status of the generation queue within our service territory. The second portion of this section describes proposed generation projects for which final interconnection studies have been completed. The third portion of this section describes some of the implications associated with interconnecting generation at various locations within our service territory.

ATC Portion of MISO Generation Queue

Over the last ten years (2013 through September 2023), 14 new generators have gone into service and five uprates or replacements to existing generators have been completed, totaling approximately 2050 MW. These generators are included in Table PR-26.

Table PR-26: Generator Requests From Past Ten Years Now In-Service

DateRequests on-lineMegawatts
3/4/2016J382 (RockGen Increase)48.3
4/27/2016J241 (Twin Falls Hydro uprate)3.7
5/1/2017J384 (Christiana uprate)21
5/8/2017J557 (Garden Corners solar)0.9
11/4/2017J395 (Quilt Block Wind Farm)98
3/31/2019J703 (Kuester)131.7
3/31/2019J704 (Mihm)56.5
10/28/2019J831 (Port Washington uprate)40
5/14/2020J390 & J760 (West Riverside)732
11/2/2020J886 (Two Creek Solar)150
9/13/2021J505 (Point Beach Solar Energy Center)100
12/1/2021J870 Badger Hollow 1150
1/7/2022J928 Garden Wind80
6/2/2022J1183 Garden Solar II1.35
10/17/2022J864 Bear Creek50
1/20/2023J1188 N Rock Solar50
1/20/2023J986 Wood County Solar150
4/4/2023J855 Red Barn92
7/27/2023R1010 Weston RICE133
Total2048

Table PR-27 lists the proposed generators in the generation queue for our service territory as of October 09, 2023, who have not yet signed the Generator Interconnection Agreement (GIA). It is important to keep in mind that the status of queued projects changes often as projects enter and withdraw from the queue, sign generator interconnection agreements and start construction. This table lists each proposed generation project and summarizes them by zone and MW amount. These proposed projects also are shown by approximate location in Figure PR-9.

As shown, the total capacity of proposed generators in this portion of the queue is roughly 12.87 GW. Of this proposed capacity, natural gas fired units reflect 8.4 percent, wind 8.5 percent, solar 50.5 percent, storage 28.5 percent, and hybrid 4.1 percent (see Figure PR-10). The hybrid units are combination of storage with wind or solar. Of the proposed capacity, 39 percent is in Zone 1, 4 percent is in Zone 2, 32 percent is in Zone 3, 18 percent is in Zone 4, and 6 percent is in Zone 5.

Table PR-27: Proposed Projects Active in the Generation Queue as of October 09, 2023

ZoneQueue #CountyProject capacity (MW)Interconnection voltage (kV)
1J1502Juneau225345
1J1508Marathon98.9115
1J1510Wood100345
1J1573Portage250115
1J1751Wood150.5138
1J1752Portage148.1115
1J1938Portage150345
1J1945Portage150345
1J2099Portage399.03
345
1J2107Portage399.03
345
1J2117Wood0138
1J2185Portage399.03345
1J2193Waushara100138
1J2277Portage0138
1J2293Adams5069
1J2326
Outagamie150345
1J2335Portage200115
1J2345Marathon150345
1J2365Portage160345
1J2366
Portage160345
1J2520Adams200138
1J2557Wood100345
1J2559Wood200345
1J2609Waushara80138
1J2833Wood4069
1J2870Sawyer243.6345
1J2944Wood350345
1J3204Clark208345
1J2439Marathon50345
1S1018Wood75138
1S1024Waushara50138
1Total5036.19
2J1750Marquette149.7345
2J1814Dickinson22.5 138
2J2029Marquette62.5138
2J2316Dickinson77.5138
2J2354Marinette6569
2J2678Delta150138
2Total527.2
3J1629Columbia200345
3J1706Green100138
3J1732Columbia98.4138
3J1746Columbia150138
3J1773Iowa, Lafayette300345
3J1779Dane200345
3J1781Iowa, Lafayette300345
3J1824Columbia67138
3J1884Columbia200345
3J1931Iowa40345
3J1935Dane50138
3J1943Columbia200345
3J1964Columbia90345
3J1983Dane25138
3J1993Columbia99345
3J2188Columbia99345
3J2271Columbia200345
3J2304Columbia400345
3J2324Winnebago3569
3J2423Columbia300345
3J2429Dane5069
3J2666Walworth100138
3J2947Rock205138
3J3152Iowa160138
3J3156Rock60138
3J3162Rock100138
3S1006Rock75138
3S1016Richland2569
3S1017Grant100138
3S1023Grant25138
3S1025Rock2569
3S1033Green25138
3S1034Dodge2569
3S1035Rock33138
3Total4161.4
4J1513Waupaca 300345
4J1615Oconto150138
4J1716Fond du Lac100345
4J1745Winnebago100138
4J1793Sheboygan75138
4J1994Fond du Lac97.088138
4J1996Shawano99138
4J2055Sheboygan100138
4J2074Outagamie75138
4J2148Outagamie150138
4J2211Brown200138
4J2218Manitowoc150138
4J2537Shawano100345
4J2544Shawano95345
4J2834Fond du Lac5069
4J3151Sheboygan150345
4J3155Winnebago150138
4J3160Fond du Lac100345
4J3161Sheboygan100138
4Total2341.09
5J1778Kenosha100138
5J1895Kenosha200138
5J1934Kenosha150138
5J2891Kenosha50138
5J3006Milwaukee300345
5Total800
Grand Total12,865.88

Table PR-28: Requests Previously in the Generation Queue Which Have been Withdrawn/Removed between June 1, 2022 and October 09, 2023

ZoneQueue #CountyProject Capacity (MW)Interconnection Voltage (kV)Generator Technology and FuelDate Withdrawn
1J1936Portage75345Storage5/31/2023
1J1937Portage75345Storage5/31/2023
1 Total150
2J1803Houghton1.669Wind10/26/2022
2J1817Houghton2069Wind10/26/2022
2 Total21.6
3J1042Walworth180138Solar8/9/2023
3J1497Jefferson125138Solar6/30/2023
3J1708Grant75138Solar6/21/2023
3J1735Rock75138Solar6/21/2023
3J1843Dane12138Gas6/21/2023
3J1930Columbia100345Storage5/31/2023
3J1954Walworth35138Storage5/31/2023
3J1955Walworth100138Solar5/31/2023
3J1971Dane45138Storage5/31/2023
3J2062Columbia100345Solar5/31/2023
3 Total847
4J1567Outagamie150345Solar6/30/2023
4 Total150
5N/A
5 Total0
Grand Total1169

Table PR-29: Active Projects in the Generator Queue in Construction or waiting construction as of October 09, 2023. It includes projects with signed GIA.

ZoneQueue #CountyProject capacity (MW)Interconnection Voltage (kV)Generator technology and fuel
1J732Douglas562345Gas
1J1002Waushara99138Solar
1R1010Marathon133115Gas
1 Total794
2J1251Marquette100138Solar
2 Total100
3J818Jefferson149138Solar
3J850Rock250138Solar
3J871Iowa100138Solar
3J947Grant200138Solar
3J1000Grant50138Solar
3J1003Dodge5069Solar
3J1154Jefferson75138Solar
3J1214Dane300345Solar
3J1304Rock65138Solar
3J1305Green49.9138Solar
3J1374Dane75345Storage
3J1374Grant67.2138Wind
3J1377Rock98.56345Solar
3J1410Dane300345Solar
3J1411Dane75345Storage
3J1460Rock200138Hybrid
3J1483Iowa99345Wind
Total2304
4J1101Manitowoc 20138Storage
4J1153Sheboygan150138Solar
4J1171Dodge100138Solar
4J1253Fond du Lac100345Solar
4R1014Sheboygan100.8345Storage
4R1015Sheboygan303.5345Storage
Total774
5J878Kenosha200138Solar
5J1316Kenosha50138Storage
5S1005Kenosha60138Storage
Total310
Grand Total4182
Includes projects with signed GIA.

Link to publicly posted MISO generation queue

Implications of generation development

From a transmission perspective, the ability of the transmission system to accommodate new generation is a function of stability, power flow and short circuit analyses. For certain generation technologies, harmonics, fast control interactions and voltage fluctuations may need to be considered as well. In most instances, new generation will require certain transmission system reinforcements to interconnect and deliver the generation output. In a few specific instances, new generation can be beneficial to the transmission system, even deferring or eliminating the need for transmission reinforcements that would be necessary absent the new generation. The ability of generation to defer or eliminate the need for transmission reinforcements also can be a function of the generation location, number of generators, and/or expected generator capacity factor.

In this section, a general zone-by-zone evaluation of the likelihood of needing or deferring transmission reinforcements for various generator locations is provided. The purpose of these evaluations is to provide a cursory indication to the generation market of the likely magnitude of the impact and the transmission reinforcements that would likely be needed by general location.

Zone 1

In Zone 1, about 39 percent (~5,036 MW, Table PR-27) of the proposed generation is located near the 345-kV infrastructure. Based on studies that we have conducted for proposed generation interconnections to date some transmission reinforcements are likely to be required for any significant generation development. The extent and nature of the reinforcements largely would be a function of where the power from the generation is to be delivered.

The transmission infrastructure in the central portion of Zone 1 includes three 345 kV lines (Gardner Park – Highway 22, Morgan – Highway 22, and Highway 22 – Werner West). These lines significantly strengthen the Weston area, bringing much needed support to the area for both stability and thermal considerations. Furthermore, the new lines included MISO Long Range Transmission plan (LRTP) Tranche 1 will significantly strengthen this area.

The infrastructure in the southern portion of Zone 1 consists of several 69 kV and 138 kV lines. The existing infrastructure in this portion of Zone 1 is not suitable for significant generation development.

Three Zone 1 generator projects went in service or are in construction in the last five years.

Zone 1 Generators In Construction or In Service

RequestSizeTypeCounty, StateStatus
J100299SolarWaushara County, Wis.In Construction
J732527.8Natural Gas - Combined CycleDouglas County, Wis.In Construction
J986150SolarWood County, Wis.In Service
R1010115Natural GasMarathon County, Wis.In Construction
Zone 1 generators in construction or in service in the last 5 years.

Zone 2

ATC has seen substantial interest in siting generators in the Upper Peninsula of Michigan. One of the major challenges proposed generation in the Upper Peninsula will face is the limited transmission infrastructure to interconnect and deliver the energy produced by these generators. Since the Upper Peninsula transmission grid was primarily designed to serve local load, transmission upgrades may be required to accommodate these proposed plants.

There are areas in Zone 2, which currently or will eventually need transmission reinforcements where smaller generation projects could be beneficial in terms of deferring transmission expenditures. The allowable capacity and potential impacts of such generation would depend on location. Impacts like thermal, stability and fault duties would need to be evaluated through the DPP process.

The following table lists Zone 2 generator projects in service or in construction in the last five years.

Zone 2 Generators In Construction or In Service

RequestSize (MW)TypeCounty, StateStatus
J5570.9SolarDelta County, Mich.In Service
J703131.7GasMarquette County, Mich.In Service
J70456.5GasBaraga County, Mich.In Service
J92880WindDelta County, Mich.In Service
J11831.4SolarDelta County, Mich.In Service
J1251100SolarMarquette, Mich.In Construction
Zone 2 generators in construction or in service in the last five years.

Zone 3

In Zone 3, about 32 percent (~4161 MW, Table PR-27) of the active generation in the queue is at various locations throughout the zone. In recent cycles, there are more proposals in Dane and Columbia Counties and along the planned Cardinal-Hickory Creek Transmission Line Project corridor (especially in Iowa and Grant Counties).

Along with the planned Cardinal-Hickory Creek Transmission Line Project, completion of the Badger Coulee Transmission Line Project and generation retirements seem to be the major drivers for new generator developments in those locations. Furthermore, the new line, terminating at Columbia 345-kV Substation, included MISO Long Range Transmission plan (LRTP) Tranche 1 will significantly strengthen the area.

Similarly, the southeast portion of Zone 3 continues to be an attractive location for siting generation. However, generation studies completed in the southwest corner of the state have demonstrated that siting large amounts of generation in rural areas may require substantial upgrades to the transmission system to ensure reliable operation.

The following table lists Zone 3 generator projects in service or in construction in the last five years.

Zone 3 Generators In Construction or In Service

RequestSize (MW)TypeCounty, StateStatus
J818149SolarJefferson County, WIIn Construction
J850250SolarRock County, WIIn Construction
J855100WindIowa County, WIIn Service
J86449.9SolarRichland County, WIIn Service
J870200SolarIowa County, WI150 MW In Service
J871100SolarIowa County, WIIn Construction
J947200SolarGrant County, WIIn Construction
J100050SolarGrant, WIIn Construction
J100350SolarDodge, WIIn Construction
J115475SolarJefferson, WIIn Construction
J118850SolarRock, WIIn Service
J1214300SolarDane, WIIn Construction
J130465SolarRock, WIIn Construction
J130550SolarGreen, WIIn Construction
J132675StorageDane, WIIn Construction
J137467.2WindGrant, WIIn Construction
J137798.56SolarRock, WIIn Construction
J1410300SolarDane, WIIn Construction
J141175StorageDane, WIIn Construction
J1460200HybridRock, WIIn Construction
J148399WindIowa, WIIn Construction
Zone 3 generators in construction or in service in the last five years

Zone 4

Generation has been proposed in various locations in Zone 4. Generation could be beneficial in a few areas depending on the capacity of such generation and exact location. Given the nature of the issues in Zone 4, it is unlikely that new generation will significantly alter the need for the major transmission reinforcements contemplated in that zone. In recent generation studies, more stress on the 138-kV path from North Appleton to South Fond Du Lac is observed and may need substantial reinforcements if the new generation projects move forward. This path is located west of Lake Winnebago and is parallel to 345-kV from North Appleton to South Fond Du Lac.

One area where generation could defer the need for transmission reinforcements is in Door County, provided such generation is small-scale and appropriately located. Currently, the northern portion of the county is served radially and electric service is subject to interruption for the loss of the single 69 kV line serving the area. The voltage profile in Door County is projected to precipitate the need for reinforcements in the future. Small-scale generation potentially could defer some of these reinforcements.

The following table lists Zone 4 generator projects in service or in construction in the last five years.

Zone 4 Generators In Construction or In Service

RequestSize (MW)TypeCounty, StateStatus
J50599SolarManitowoc County, WIIn Service
J886150SolarManitowoc County, WIIn Service
J110120StorageManitowoc County, WIIn Construction
J1153150SolarSheboygan County, WIIn Construction
J1171100SolarDodge County, WIIn Construction
J1253100SolarFond du Lac, WIIn Construction
R1014100.8StorageSheboygan, WIIn Construction
R1015303.5StorageSheboygan, WIIn Construction
Zone 4 generators in construction or in service in the last five years.

Zone 5

With proposed development of Paris 345-kV Substation, Kenosha County is expected to get some reinforcement to the local transmission capacity and that may make it attractive for new generators to locate there. In the MISO and PJM generation studies, there seems to be a possible need for an additional 345-kV tie line between ATC and Commonwealth Edison (ComEd) or local 345-kV reinforcement to handle regional flows driven by new generation and retirements.

The following table lists Zone 5 generator projects in service or in construction in the last five years.

RequestSizeTypeCounty, StateStatus
J83140GasOzaukee County, WIIn Service
J878200SolarKenosha County, WIIn Construction
J131650StorageKenosha County, WIIn Construction
S100560StorageKenosha County, WIIn Construction