Studies and Reports > 2009 MN Biennial Report > TC Planning Zone > Needs: 6.5.18 Scott County-Carver County Area

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6.5.18 Scott County-Carver County Area

Tracking Number. 2009-TC-N5

Utility. Great River Energy

Inadequacy. This area includes the 69 kV system that runs south from the Carver County and Scott County substations toward the New Prague area. The Carver County to Belle Plaine 69 kV line was found to experience thermal loading problems during contingencies in the area in the 2014 timeframe. The New Prague area will also experience low voltage problems during contingencies.

A map of the area is shown following the discussion.

Alternative. Two options were considered for this area. The first option recommends installation of capacitor banks and using local generation to address the deficiencies of the area. The second alternative builds on the first option and recommends rebuilding overloaded transmission lines and establishing new sources in the area. The options are discussed below.

Option 1: Capacitor banks installation and local generation

This option involves installing capacitor banks at Veseli and Merriam Junction along with running local generation for improving voltage and line loading in the area. While this option is capable of supporting the voltage in the area, it is not sufficient to address the Carver County to Assumption 69 kV line overload problems in the area.

Option 2: 69 kV to 115 kV upgrades

This option recommends implementing Option 1 in addition to rebuilding overloaded lines and establishing a new source in the area. In addition to rebuilding the Carver County-Assumption 69 kV line to 115 kV standards for continued 69 kV operation, this option recommends rebuilding the remaining 69 kV facilities including the Assumption to Belle Plaine 69 kV line to the 115 kV standard to complete the Carver County-Helena-New Prague 115 kV line. A 115/69 kV substation is recommended at New Prague in the 2016 timeframe when the 69 kV lines are upgraded to 115 kV.

Analysis. Option 2 addresses both the voltage and line loading problem of the area for the long term. The CapX 2020 projects include a 345 kV Helena Substation. This plan proposes a 345/115 kV substation at Helena, which will serve the 115 kV system from Carver County and Lake Marion. Note that the Glendale-Lake Marion area study proposes a 115 kV circuit from Lake Marion-Helena, which would connect with the Carver County-Helena 115 kV line in this plan.

Distributed generation is not a desirable option to address the deficiencies in this area. The deficiencies constitute a geographically large area and the recommended option helps craft a long term solution for the Glendale – Lake Marion area transmission deficiencies (see Tracking Number 2009-TC-N2). Distributed generation would require significant investment and involve a considerable incremental cost to keep up with the load growth in this and neighboring areas.

Schedule. This project is tentatively scheduled to be in-service between the 2014 and 2016 timeframes.

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