Studies and Reports > 2009 MN Biennial Report > WC Planning Zone > Needs: 6.4.17 Elk River-Becker Area

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6.4.17 Elk River-Becker Area

Tracking Number: 2009-WC-N6

Utility: Great River Energy

Inadequacy. This area is served by the Elk River 230/69 kV source and the Liberty 115/69 kV source. Load growth is causing loading concerns on the 69 kV system between the Elk River and Liberty substations and on the Elk River and Liberty transformers. This transmission system serves the Highway 10 corridor between Elk River, Big Lake, and Becker and has the potential to experience significant growth.

Transformer loading issues can be eased by the addition of a second Liberty 115/69 kV transformer. GRE had planned for this transformer addition when the Liberty substation was constructed and this will be pursued as an option when the remaining Liberty transformer capacity diminishes. However, area loads will eventually grow to the point that a loss of one transformer bank at Elk River or Liberty will cause the second bank at either location to exceed safe operating limits.

A map of the area is shown following the discussion.

Alternatives. GRE is focusing on reconductoring and temperature upgrades of existing lines to address near-term 69 kV line loading issues. Otherwise, two options have been considered as future solutions.

Alternative 1: New Elk River Area 345/115 kV source and Elk River-Waco-Liberty 11569 kV double circuit line.

Alternative 2: New Foley 230/69 kV source and various Elk River-Liberty 69 kV line rebuilds.

Analysis. Alternative 1 would be attractive from the standpoint that a double circuit 115/69 kV line would provide more capacity to a narrow transmission corridor than either a single circuit 115 or 69 kV line could offer. Furthermore, the Waco breaker station was designed to accept a 115/69 kV transformation and such a transformer would offload the Elk River 230/69 kV transformers. An Elk River Area 345/115 kV source would also offer a termination point for a 115 kV line going east towards the Crooked Lake substation (See Twin Cities Zone Tracking Number 2003-TC-N12).

Alternative 2 would require much less up-front investment and would provide sectionalizing capability to a part of the GRE 69 kV system with a lot of line exposure. The Foley source would also provide backup to the Benton County 230/69 kV transformer. It is unknown, however, if Alternative 2 would totally eliminate the need for a 115 kV solution in the area as the source is somewhat distant from the load pocket along Hwy. 10.

Schedule. GRE is still evaluating options for this area. Depending on load growth, a new Liberty 115/69 kV transformer could be needed as soon as 2013. The need for either Alternative 1 or Alternative 2 is not expected to occur until at least 2017-2018. GRE will carefully monitor the area load growth to see when a solution needs to be implemented.

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