Refer to Table ZS-1 and Figure ZS-1

• The Rhinelander Loop will require completion of the proposed interconnection to other portions of the system in order to reliably serve load in the 2010 and beyond timeframe.
• In order to accommodate the proposed generation in the Wausau area, an additional 345-kV line will be required. The difference between the in-service dates of the proposed generation and the 345-kV line needed for the generation will require that lower-voltage upgrades take place before the generation is placed in service with operating restrictions until the 345-kV line is energized.
• Low voltages at and near the Council Creek substation in the Tomah area will require that a combination of reinforcements be implemented to reliably serve load in the future.

In addition to the recently completed Arrowhead-Gardner Park 345-kV facility additions at the Weston Power Plant site, a new 550-MW generator also was constructed at this site in 2008. ATC has conducted generator interconnection studies and transmission service studies to ensure the generator can be operated without stability limitations and the output of the generator can be delivered reliably. The analyses showed that the addition of the generator will cause overloads and system instability if the transmission system in this area is not reinforced. The analysis indicates that a new 345-kV line from the Gardner Park Substation is needed to maintain stability and to deliver the generator output, in addition to the Arrowhead-Gardner Park 345-kV line.

Based on the results of the Weston generator studies, ATC is planning the following transmission project. Appropriate applications to the Public Service Commission of Wisconsin were approved in July 2006.

• Construct a new 345-kV line from the Gardner Park Substation to a new substation, currently called Highway 22, located near the midpoint of the proposed Morgan-Werner West 345-kV line (near Shawano). We are proposing to license, permit, construct and place this line in-service by December 2009.

The Weston 550-MW generator was placed in-service in June 2008, and the projected in-service date for the Gardner Park-Central Wisconsin 345-kV line is December 2009. Based on the 18-month in-service date difference between the generator and 345-kV line project, additional studies were performed to determine if any feasible projects exist for delivery of all or a portion of the generator capacity prior to the in-service date of the Gardner Park-Central Wisconsin 345-kV line project. The interim transmission service and generator interconnection studies identified the following recently completed projects that will allow the generator to operate during this interim period. Full generator operation, without the associated interim Weston 4 Special Protection System, will not be allowed until all required 345-kV lines are placed in service.  The recently completed projects are:

• reconductor Weston-Northpoint 115-kV line,
• uprate Weston-Kelly 115-kV line,
• rebuild Weston-Sherman St. and Sherman St.-Hilltop 115-kV lines as double circuits with the second circuit on each section being the new Gardner Park-Hilltop 115-kV circuit, and
• uprate Kelly-Whitcomb 115-kV line.

We are working in cooperation with Dairyland Power Cooperative and Xcel Energy to develop a more comprehensive long-term solution to address reliability issues in the Tomah area as well as the limitations of the Monroe County-Council Creek transmission corridor. The proposed solution is to replace the existing 69-kV circuit between the Monroe County and Council Creek Substations with a new 161/69-kV double-circuit line in 2012.

The portion of the transmission system referred to as the Rhinelander Loop consists of the 115-kV facilities in north central Wisconsin or, more specifically, the 115-kV network north of Wausau. The Rhinelander Loop is particularly sensitive to low voltage during certain contingencies. A primary reason for this condition is that summer loads within the Rhinelander Loop have exceeded what had been forecasted prior to ATC’s formation. This higher-than-anticipated load growth has accelerated the potential for such low voltages under single contingency conditions.

As part of the analyses of potential solutions for the Rhinelander Loop, we considered additional system issues that needed to be addressed on the adjacent 69-kV network to the north of the Rhinelander Loop (in Zone 2) and transfer capability needs between Wisconsin and Michigan’s Upper Peninsula.

Due to the severity of the problems, it was necessary to address the needs of the Rhinelander Loop in stages. The short-term solution, that is, projects that were implemented prior to 2005 to address the immediate needs of the loop, included the conversion of WPS’s 46-kV system between Pine-Grandfather-Tomahawk-Eastom to 115 kV and constructing a new 115-kV line between Skanawan and Highway 8 substations. The conversion was completed in early May 2004 and the new 115-kV line was completed in June 2005.

Based on the prior analyses, ATC's preferred longer-term solution is to construct a new Cranberry-Conover 115-kV line (currently in-service) and rebuild the Conover-Iron River-Plains 69-kV line and convert to 138-kV operation. This alternative addresses the longer-term reliability issues of the Rhinelander Loop, provides substantial voltage support to the 69-kV system in the western portion of the Upper Peninsula and addresses potential long-term condition issues due to the age of the existing 69-kV system. The new 115-kV line between Cranberry and Conover was completed in June 2008 with the remainder of the project completed by June 2010 to meet reliability needs for serving the Rhinelander Loop. The 2010 date for the Conover-Plains portion of the project is only permissible by implementing some interim procedures and solutions. Without the Conover-Plains portion of this solution, overloads and voltage issues begin to reappear in the Wausau/Rhinelander Loop area in this timeframe.

To address low voltages elsewhere in Zone 1, capacitor bank upgrades are needed at the Berlin Substation in 2008. To address facility overloads, the existing 47 MVA Metomen 138/69-kV transformer will be replaced with a 100 MVA transformer in 2013. Overloads on the Arpin 345/138-kV transformer and Arpin-Sigel 138-kV line are being addressed by the Arpin Operating Guide. The low voltages at the Council Creek 138-kV Substation are being addressed through manual control of load tap changers on the Council Creek 138/69-kV transformer.

In response to customer requests for a new distribution interconnection, a new 69-kV transmission line for the Warrens Substation (formerly known as Mill Creek) will be placed in-service in 2010 by interconnecting to the Council Creek-Tunnel Creek 69-kV line. In 2012, a new 115-kV transmission line is needed from Clear Lake to the new Arnett Road distribution interconnection. The Fairwater distribution interconnection in the greater Ripon area will require a new 69-kV transmission line. The proposed Fairwater Substation will require a new radial 69-kV line be extended from the Brandon 69-kV Substation in 2010.

A new proposed project is the rebuilding of the Arpin–Rocky Run 345-kV circuit. This maintenance-driven project will improve the circuit’s reliability, and ensure safety and our compliance with current code requirements. Subsequent to an extensive study, our Asset Management organization concluded that the Arpin–Rocky Run 345-kV transmission line is structurally deficient and is capacity limited due to insufficient conductor-to-ground clearances.  Thus, ATC is in the process of preparing an application to be submitted to the WPSC in 2008 with an anticipated completion date for the rebuild in 2010.

Projects whose “Need date” precedes  the “In-service date”

none