Xcel Energy Smaller Scale Transmission

ProjectsNorthern MAPP Subregional

Planning GroupApril 3, 2007

Srinivas Vemuri, Jason Standing, and Daniel Kline

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Small Project Information

T-Corners Transformer Replacement Hyland Lake – Dean Lake 115 kV Upgrade Woodbury – Tanners Lake Upgrade Northeast Mankato 69 kV Plan South Shakopee Substation Ironwood Second Transformer Ironwood Bus Upgrade Lawrence Second Transformer Tracy Switching Station Capacitors Keegan Lake – Lebanon Hills Prescott 10 MVAR Cap Bank

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T-Corners 115/69 kV Transformer Replacement Substation currently has two 115/69 kV

transformers (#1 & #2) Tx #1 – 62.5 MVA Tx #2 – 112 MVA

Summer 2011 – Loss of Transformer #2 will load #1 to 80 MVA (128%)

Plan to replace existing 62.5 MVA bank with matching 112 MVA bank

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T-Corners 115/69 kV Transformer Replacement

Eau ClaireMetro Area

T-Corners

52 Miles

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Ironwood Second Transformer

Ironwood 88/34.5 kV Transformer currently rated at 25 MVA

78 MW generation at Bayfront Substation Loss of Bayfront 115/92 kV transformer sends

Bayfront generation through 88 & 34.5 kV systems Severely overloads Ironwood – Bayfront 88 kV line Severely low voltages along Ironwood 34.5 kV system

Add second Ironwood 88/34.5 kV transformer

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Ironwood Second Transformer

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Ironwood Terminal Equipment Upgrade Ironwood – Bayfront 115 kV conductor rated at 189

MVA (850 Amps) Ironwood 115 kV substation equipment with various

ratintgs 200 Amp CT 300 Amp Wave Trap 380 Amp Bus 400 & 800 Amp Breakers, 600 Amp Switches

Outage of Bayfront – Saxon Pump 88 kV line loads Ironwood 115 kV to 72 MVA (361 Amps)

Outage of Bayfront 115/92 kV transformer loads Ironwood 115 kV to 87 MVA (437 Amps)

Replace capacity-limiting terminal equipment

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Lawrence Second 112 MVA Transformer This project is to add an additional 115/69

kV, 112 MVA transformer at the Lawrence Substation in Sioux Falls. This is needed due to the double-circuit outage of the 115 kV line out of Split Rock to Cheery Creek.

In Summer 2011, loss of Split Rock-Cherry Creek and Split Rock-West Sioux Falls double-circuit outage results in a loading of 145.9 MVA (130.2%) of the 112 MVA transformer at Lawrence.

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Lawrence Second 112 MVA Transformer

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Tracy SW 12 MVAR CAP

This project is to replace the existing 5.4 MVAR, 69 kV cap bank at the Tracy Switching Station with a new 12 MVAR cap bank.

In Summer 2006, for loss of the Lyon County 69 kV source, the following buses have low voltage:

  Walnut Grove = 0.855 pu

Tracy SS = 0.856 puLake Sarah = 0.860 puCurrie = 0.872 puSlayton = 0.886 puHadley = 0.898 puLake Wilson = 0.905 pu

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Tracy SW 12 MVAR CAP

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Kegan Lake – Lebanon Hills 69 kV Line Upgrade Reconductor the 3 #8 CU section of the

Kegan Lake – Lebanon Hills 69 kV line to at least 48 MVA.

During 2011 summer peak conditions, the line overloads to 110.5% in the base case.

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Kegan Lake – Lebanon Hills 69 kV Line Upgrade