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Studies and Reports > 2009 MN Biennial Report > SE Planning Zone > Needs: 6.7.2 Rochester and Southeast Minnesota Areas

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Transmission Projects Report 2009
Section 6.7: Southeast Zone
 
p. 253

6.7.2 Rochester and Southeast Minnesota Areas

Tracking Number. 2003-SE-N1

Utility. Xcel Energy, Dairyland Power Cooperative, Rochester Public Utilities, Southern Minnesota Municipal Power Agency, and Wisconsin Public Power Inc.

Inadequacy. Transmission issues in the Rochester and Southeast Minnesota area were first reported on in the 2003 Biennial Report. The following issues have been identified:

  1. Rochester load. The loss of the Byron – Maple Leaf 161 kV line would limit the input into the Rochester area to about 160 MW, when the summer peak demand is 300 MW. And load growth is projected to require even more power in the area.
  2. Transfer limit. The capacity of the Byron – Maple Leaf 161 kV line is a limiting factor in setting the available transfer capability for Minnesota to Wisconsin transfers.
  3. Load serving the greater LaCrosse area. The Greater LaCrosse Area, electrically, includes Winona, LaCrescent, Houston, and Caledonia as well as a significant area surrounding LaCrosse on the Wisconsin side of the Mississippi. In the 2005 Report, it was reported that the loss of the Genoa-LaCrosse-Marshland 161 kV line created an overload on the Genoa – Coulee 161 kV line. In 2007 the Genoa – Coulee 161 kV line was reconductored to 377 MVA. With this reconductor the Genoa – LaCrosse 161 kV line overloads for the loss of the Genoa-Coulee 161 kV line. This overload is exacerbated by an outage of the generator at the Alma site.
  4. Serving Regional Load. Due to numerous constrained flow-gates within the MAPP and Midwest ISO areas, utilities have experienced difficulty securing firm transmission service to deliver firm generation purchases from sources within and outside the MAPP region. In addition, utilities have encountered difficulty locating possible new generation within their service areas due to these constraints. For those utilities within MISO, transmission is less of an issue with respect to energy; however demonstration of firm transmission for capacity accreditation remains a requirement for any capacity purchases in excess of 10% of network load. Lack of firm transmission exposes these utilities to high energy costs. The inability to secure firm transmission has also limited the sale of excess generation.

It should be noted that in October 2006, the person serving as the Independent Market Monitor for MISO declared a broad area, including the Southeast Transmission Zone, a Narrowly Constrained Area (“NCA”) under the MISO tariff. FERC subsequently accepted the designation. This designation indicates that the area is subject to high congestion charges due to the need to re-dispatch more costly generation (peaking capacity) to alleviate constraints on the area’s transmission system. Because of the electrical location of some generators, these constraints can give the operator “market power” placing area load at a disadvantage. By designating the region an NCA, the operators are limited to their offer prices. The Independent Market Monitor indicated in his report that the NCA condition was likely to continue for some time and remains in effect at the time of this report.

  1. CapX 2020 Vision Plan. In order to serve projected new load in Minnesota, major additions to the 345 kV system in the state are required with access to regions outside of Minnesota. One of the vision projects identified is the need for a 345 kV line from the south side of the Twin Cities to eastern Wisconsin.
  2. Adams-Rochester 161 kV Line. This line overloads due to the addition of new wind generation and has been given its own Tracking Number (2007-SE-N1).

A map of the area is shown following the discussion.

Alternatives. As part of the CapX 2020 process, the utilities considered two options for a 345 kV line between the Twin Cities area and LaCrosse, Wisconsin. One option was a line from a new Hampton Corner Substation in Dakota County, Minnesota, to LaCrosse and the other option was a line from Prairie Island to LaCrosse. The utilities determined that the line from Hampton Corner was the preferred option.

The 345 kV line from Hampton Corner to LaCrosse also includes a new substation, called the North Rochester Substation, and a 161 kV segment continuing for about 10–15 miles from the North Rochester Substation to the Northern Hills Substation in the Rochester are. In addition, a 161 kV line extending south from the North Rochester Substation to the Chester Substation is also part of the proposal, with the option to construct that segment to 345 kV capability.

Analysis. The major study effort for these deficiencies is the Southeastern Minnesota-Southwestern Wisconsin Reliability Enhancement Study, dated March 13, 2006 (SE 345 kV Study). In August 2007 Xcel Energy and GRE filed an application for a Certificate of Need with the Public Utilities Commission for the Hampton-North Rochester-LaCrosse line, including the 161 kV segments. In August of 2009, the Minnesota Public Utilities Commission granted a Certificate of Need for the CAPX projects which included the Hampton Corner - North Rochester – North LaCrosse 345 kV line, plus the North Rochester – Northern Hills 161 kV line and the North Rochester – Chester 161 kV line.

The utilities are still investigating routing issues. There are two main routing options under review. One routing option generally follows US Highway 52. The other generally tracks south from Hampton Corner and then generally east to North Rochester. The North Rochester 345/161 kV substation taps the existing Prairie Island-Byron 345 kV transmission line on the northwest side of the city of Rochester.

The North Rochester – LaCrosse segment routing is driven by the suitable Mississippi River crossing candidates. The candidates are from north to south – Alma Winona, and La Crescent – and all three have existing overhead transmission crossings.

Schedule. An application for a Route Permit for the 345 kV line and the 161 kV lines will be filed with the Minnesota Public Utilities Commission by the end of 2009. The timeframe for placing the new 345 kV and 161 kV facilities into service is 2012-2015.

 


Transmission Projects Report 2009
Section 6.7: Southeast Zone
 
p. 255

Click here or on map below to download high resolution PDF map.