CLICK for LINK TO UPDATED INFORMATION, November 2007

Providing some information about connection facilities for proposed generators that have requested but not completed interconnection studies is one purpose of this section of the Assessment.

The size and location of new or expanded power plants can have significant impacts on the transmission system. These impacts can range from very positive (adding voltage support in a weak area of the system) to very negative (aggravating loading problems and/or causing generator instability). Information on the status, as of July 1, 2006, of ATC’s portion of the Midwest Independent System Operator generation interconnection queue is provided in this section.

While reduced from previous years, there continues to be significant activity in ATC’s portion of this queue, ranging from newly proposed generation projects to cancellation of previously proposed generation projects. This dynamic situation is a challenging aspect of the transmission planning environment, as regular changes in the generation planning environment must be correspondingly accommodated.

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.

Per the Midwest ISO Attachment X process, interconnection impacts are assessed via up to three interconnection studies. The first study, called a feasibility study, includes a determination of thermal overload or voltage level impacts created by the new generator. The second study, called an impact study, includes a determination of whether the proposed generator and other nearby generators will remain stable under various disturbance situations, like line trips and equipment failures. It also includes a fault study analysis to determine whether existing system equipment can accommodate the increased short circuit fault duty caused by the new generator. It also identifies solutions for any thermal, stability or fault duty problems. If problems are identified in the impact study, a third study, called a facility study, is conducted to settle on solutions and provide cost and time estimates for construction. Delivery impacts are assessed during the interconnection study process using the Midwest ISO deliverability methodology, which determines whether a new generator is deliverable to the Midwest ISO Day 2 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 the Midwest ISO’s Module E Resource Adequacy procedures.

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. This is why we included in our Assessment models of those proposed generators for which interconnection studies have been completed.

The first portion of this section provides the status of the generation queue within our service territory. The second portion of this section describes the transmission system additions associated with various 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 Generation Queue

Since ATC’s inception, ten new generators have gone into service and one uprate to an existing generator has been completed, totaling 2,669 MW. These generators are shown in Table PR-29.

Table PR-30 lists the proposed generators in the generation queue for our service territory as of July 1, 2006. 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-10. As shown, the total capacity of proposed generators in the queue is 5316.5 MW. Of that proposed capacity, 59 percent reflects new coal units; wind units reflect 26 percent; combined cycle (natural gas) units reflect 13 percent; and the remaining 2 percent is comprised of simple cycle (natural gas) turbines and an uprate of an existing steam plant using biogas (see Figure PR-11). 49 percent of this generation is proposed in Zone 5, 12 percent in Zone 1, 13 percent in Zone 3, 20 percent in Zone 4, and 6 percent in Zone 2.

The developer projected in-service date listed in Table PR-30 is the last official commercial operation in-service date provided by the developer for that request. A developer may, per the Midwest ISO’s Attachment X procedures, suspend their Interconnection Agreement which may delay the project. A developer is not required to update their official in-service date as part of this suspension.

The following requests have been suspended:

• G282
• G338
• G353
• G354
• G366
• G368
• G384
• G483

Generation interconnection requests previously in the generation queue, which have been cancelled or removed from the queue since July 2005 (because the developer withdrew the request or missed contractual milestones), are summarized in Table PR-31.

Link to publicly posted generation queue: http://oasis.midwestiso.org/documents/ATC/queue.html

Transmission associated with proposed generation interconnections

Prior to the start of the MISO Day 2 Market, transmission service for new generators was handled separately through an OASIS transmission service request(s). For generators listed below that had studies completed prior to Day 2 start-up, system reinforcements were identified through both generator interconnection and transmission service studies.

Implications of generation development

There are several aspects to be considered in siting generation. Availability of fuel, water and transmission are key among those.

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 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, perhaps 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 very 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 very 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

Within Zone 1, generation has been proposed in various locations, but most of the proposals have involved generation located in the vicinity of the 345-kV infrastructure. Based on studies that we have conducted for proposed generation interconnections and transmission service from this area to date, some transmission reinforcements are likely to be required for any significant (>100 MW) 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 northern portion of Zone 1, the Rhinelander Loop, is a potential candidate for moderate-sized (up to 150 MW, depending on location) generation development, provided generator stability can be maintained, and provided it can be located in the northern portion of the Loop. Generation in this area could defer the need for transmission reinforcements planned to be implemented in the 2008-2010 timeframe. Whether this generation would be cost-effective as a transmission-deferral mechanism would depend on a number of factors. The need for additional reinforcements outside of the Loop would be a function of where the power from the generation is to be delivered.

The infrastructure in the southern portion of Zone 1 consists of a couple of 138-kV lines and several 69-kV lines. Only smaller generation projects (<25 MW) could be accommodated with minimal transmission reinforcements. The existing infrastructure in this portion of Zone 1 is not suitable for any significant generation development.

Zone 1 completed generation study links:

http://oasis.midwestiso.org/documents/ATC/GIC044 System Impact Study report.pdf

http://oasis.midwestiso.org/documents/ATC/GIC044_Facility_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G376_Evaluation_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G376_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G522_Feasibility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G522_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G523_Impact_Study.pdf

Zone 2

We have completed two generation interconnection studies in Zone 2 and currently are building a base of knowledge similar to that which we have in other zones relating to likely generation interconnection impacts.

The most logical locations from a transmission infrastructure standpoint would be near the existing Presque Isle Power Plant or the Plains Substation due to the number of 138 kV lines emanating from these substations. However, any significant generation development at or near the Presque Isle Power Plant likely would require transmission reinforcements or additions due to the existing stability issues there. The completion of the Northern Umbrella Plan, however, will result in a much more robust 138-kV network at Plains Substation that could accommodate a reasonable amount of generation in the future at or near Plains.

It is likely that given the scarcity of 138-kV infrastructure in the Upper Peninsula there are virtually no other locations in Zone 2 that are ideal candidates for significant generation development.

There are areas in Zone 2, such as on the western end of the Upper Peninsula, which are or will be in need of transmission reinforcements where smaller generation projects could be beneficial in terms of deferring transmission expenditures. The allowable capacity of such generation would depend on the location. However, other potential impacts (stability, fault duties) would need to be evaluated on a location-by-location basis.

Zone 2 completed generation study links

http://oasis.midwestiso.org/documents/ATC/G583_Feasibility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G567-568_Feasibility_Study.pdf

Zone 3

In Zone 3, generation has been proposed in various locations, but over half have been in the southern-most counties in Zone 3. Generation could be beneficial in a few areas depending on the capacity of such generation and the exact location.

We are projecting that the Madison area is going to become subject to voltage instability in the next five or six years. Thus, we believe that extending the 345-kV network to the west side of Madison coupled with additional 138-kV reinforcements within the city will resolve this issue over the long term. Generation on the west side of Madison potentially could defer the need for portions of these reinforcements provided the generation is not too large (> 200 MW), provides dynamic reactive power support and is appropriately located.

In Sauk County, though we are currently reinforcing the system, the area still is projected to need transmission reinforcements in the future to ensure reliable operation. Smaller-scale generation (< 100 MW) in certain locations could be beneficial to improving the voltage profile in the area and potentially deferring transmission reinforcements. Stability analysis would need to be conducted to ensure stable operation of such generation.

Similarly, the southeast portion of Zone 3 is heavily loaded and will require transmission reinforcements in the future to ensure reliable operation. Small-scale generation in certain locations could be beneficial to changing power flow patterns and improving the voltage profile in the area.

Zone 3 completed generation study links:

http://oasis.midwestiso.org/documents/ATC/G281-282_System_Impact_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G282_Facility_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G338_System_Impact_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G338_Facility_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G366_System_Impact_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G366_Facility_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G371_Evaluation_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G483_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G483_Facility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G527_Feasibility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G527_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G528_Feasibility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G528_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G546_Feasibility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G550_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G553_Feasibility_Study.pdf

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, however, it is unlikely that new generation in Zone 4 will significantly alter the need for the major transmission reinforcements contemplated in that zone.

One area where generation could defer the need for transmission reinforcements is in Door County, provided such generation is small-scale (< 50 MW) 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 certain of these reinforcements.

One area in Zone 4 that cannot accommodate any additional generation without significant transmission reinforcements is in the vicinity of the Point Beach and Kewaunee nuclear plants. In this area, existing transmission lines have little excess capacity. As the system evolves, stability margins at those plants may become a concern. Additional generation would exacerbate those limitations.

Zone 4 completed generation study links:

http://oasis.midwestiso.org/documents/ATC/G240 System Impact Study Report.pdf

http://oasis.midwestiso.org/documents/ATC/G240 Facility Study Report.pdf

http://oasis.midwestiso.org/documents/ATC/G338_System_Impact_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G353_G354_Facility_Study_Report.pdf

http://www.midwestiso.org/plan_inter/documents/G368_Evaluation_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G368_Facility_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G376_Evaluation_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G376_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G376_Facility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G384-410_Evaluation_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G384-410_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G384_Facility_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G421_Evaluation_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G427_Evaluation_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G486_Impact_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G507_Feasibility_Study.pdf

http://oasis.midwestiso.org/documents/ATC/G590_Feasibility_Study.pdf

Zone 5

Two major generation additions have been proposed in Zone 5. The first addition is at Port Washington Power Plant, which has been approved by the Public Service Commission of Wisconsin. Two groups of units will be installed. The first phase went in service in 2005 and the second phase is under construction to go in service in 2008. Rebuilding existing transmission lines in the Port Washington area is required to support this new generation.

The other site for new generation is at the Oak Creek Power Plant. The Public Service Commission of Wisconsin has approved two units at Oak Creek Power Plant, with the first unit going into service in 2009 and the second unit in 2010.

Studies of other proposed generation projects that are no longer in the generation queue indicate that additional generation in certain areas of Zone 5 would pose stability problems. In particular, larger-scale generation interconnecting to the 345-kV network could pose stability issues.

Smaller-scale generation in certain locations in Washington and Waukesha counties potentially could be accommodated without the need for transmission reinforcements if located appropriately.

Zone 5 completed generation study links:

http://oasis.midwestiso.org/documents/ATC/G051_Facility_Study_Report_Rev1.pdf

http://oasis.midwestiso.org/documents/ATC/GIC027_Impact_Report_Rev1.pdf

http://oasis.midwestiso.org/documents/ATC/GIC027_Facilities_Study_Report.pdf

http://oasis.midwestiso.org/documents/ATC/G510_Impact_Study.pdf