Refer to Table ZS-2 and Figure ZS-18

Summary of key findings

• Additional var support is required in the greater Milwaukee area.
• Potential thermal violations indicate the need for facility upgrades in the Waukesha and Kenosha areas.
• Thermal, voltage, and load serving issues in Kenosha and Walworth might be resolved with a 138-kV line between Spring Valley and North Lake Geneva

Sixteen 138-kV buses in Waukesha and Washington County experience low bus voltage under NERC Category A or TPL-001-0 conditions (intact system) in 2013.  The buses are Concord (90.6%), Allerton (94.7%), Bark River (91.8%), Edgewood (94.4%), Cooney (90.0%), Cottonwood (90.5%), Germantown (91.7%), Hartford (92.6%), Merrill Hills (92.7%), Mukwonago (93.8%), Maple (92.3%), St. Lawrence (94.0%), Summit (90.2%), Sussex (94.9%), Arthur Road (94.0%), and Glacier (94.5%).  These low intact system bus voltages occurred because Concord and Germantown generation was modeled out of service in 2013 as a result of new generation at Oak Creek.  The new generation is scheduled to be placed in service prior to the summer of 2010. 

Two-32.4 MVAR capacitor banks are scheduled to be placed in service at Summit by June 2010 to improve area bus voltages.  In the interim, dispatching Concord and/or Germantown will provide var support to improve area voltage. 

Additional reactive sources are required in the greater Milwaukee area. In addition to the Summit capacitor banks, 225 MVAR of capacitance will be installed at the Bluemound Substation in 2010.

Following are the results of the 2013 contingency analysis (NERC Category B or TPL-002-0 conditions) performed on Zone 5.    

An outage of either one of the Arcadian–Waukesha 138-kV lines (KK9962 and KK9942) results in the other Arcadian–Waukesha 138-kV line overloading by 14-15 percent. The limiting element is the line conductor with clearances set for operation at 200 degrees. The line conductor clearances will be increased in 2010 to permit higher flows under contingency conditions.

An outage of the Arcadian 345/138-kV transformer T1 causes the Arcadian 345/138-kV transformer T3 to overload by 10 percent. As a result, a provisional project to install 1-345/138-kV 500 MVA transformer to replace these two existing transformers is being considered in the 2011 timeframe.

Projects New in this Assessment

The Albers-Bain 138-kV line loads to 96 percent of its summer emergency limit for an outage of the Bain-Kenosha 138-kV line. The limiting elements are bus jumpers at Bain Substation and the line conductor clearances. This line will be upgraded in 2010.

A project to install a second Shorewood-Humboldt underground cable in 2012 is under consideration to accommodate additional distribution load (2009) at the Shorewood Substation under contingency conditions. Under the Cornell-Shorewood 138-kV underground contingency, there is very little load bridging capability. A parallel Shorewood-Humboldt underground line will eliminate a potential load shedding situation.

A provisional project to uprate the Bain-Kenosha 138-kV line is being considered to resolve potential thermal overloads under single-contingency conditions in 2013.

Thermal, voltage, and load serving issues in Kenosha and Walworth County might be resolved by constructing a 138-kV line from Spring Valley to Twin Lakes, continuing on to South Lake Geneva.  This would entail acquiring new right-of-way between Spring Valley and Twin Lakes.  The remaining segment between Twin Lake and North Lake Geneva could make use of an existing right-of-way. Studies are underway to determine the course of action to alleviate the issues in the area. This project would also coordinate with a Zone 3 project, the North Lake Geneva-South Lake Geneva 138-kV line with a 2014 in-service date.  Please refer to Zone 3 – 2013 study results for details about the North Lake Geneva-South Lake Geneva 138-kV line project.