Dispersed Renewable Generation Transmission Study

by Mike MichaudMatrix Energy Solutions

June 27, 2008

STUDY SCOPE

ó Analyze transmission impacts of 1200 MWof new dispersed renewable generation

located statewideó Two phasesó Study Phase I: 600 MW

– Report by OES due June 2008ó Study Phase II: 600 MW

– Report by OES due September 2009

Transmission Modeling

ó MTEP07, 2013 Summer Peak and Off-Peak modelsó Removed Line/Facilities which will not be in-service

before or during 2010.ó Integrated GRE-LRP transmission model detailó Gather additional detail from Minnesota utilitiesó Added Lower Voltage Lines (34.5 kV, 41.6 kV, 46

kV)ó Re-allocated loads from higher voltage to lower

voltage busesó Prior queued generation was not included in the

study model.

Substation InformationóWind Profile Information

Used GIS data & DOC Wind Maps to get capacity factor at substations

ó Distribution Transformer InformationGathered Maximum Load, Minimum Load & Transformer

MVA Ratingó Gathered Data on 2253 Substations at 34.5 kV or

Higher Voltages

Screening Methodology/Criteria

ó Utilized DC Analysis of incremental transfer capability to select DRG Short List sitesó Selected lower-voltage generation study sitesó Screened promising sites further by wind profile

(Minimum of 35 % Capacity Factor)

ó Divided sites equally among planning zonesó Added Biomass site to Short List

First Substation Short List Map

AC AnalysisSingle Site

Dorsey Transformer Issues

RESULTS

The analysis successfully demonstrated a DRG scenario where 600 MW could be sited without significantly affecting any

transmission infrastructure.

RESULTS

The analysis demonstrated that fixing the Dorsey transformer problem will likely

unlock significant opportunity for more dispersed generation

in the Northern half of the state.

RESULTSDORSEY OPTIONS IDENTIFIED

ó Install a third 1200 MVA, 230/500 kV transformer at Dorsey ($41 M)ó Install phase shifters on three northern 230 kV lines

($60M)ó Install a Special Protection Scheme to curtail Minnesota

generationó Communicate and coordinate a DC Runback resolution

with Manitoba Hydro

RESULTS

The utilities have now created a statewide computer model of the lower voltage

transmission system that can be the basis for further study work.

RESULTS

OES plans to convene and facilitate a technical working group in the second half of 2008 to

look into actions necessary, in coordination with the Midwest ISO and with the Minnesota

utilities, to interconnect potential DRG projects with a focus on lower voltage

interconnections.

RESULTS

We now have available an analysis of likely injection potential for generation

installed at virtually every substation in the state with an indication of

likely wind turbine capacity factors.

RESULTSThe analysis found 393 substations

throughout the state that passed all the screening tests.

Only 20 of these were used to create the result that 600 MW of Generation outlet

could be developed with no necessary transmission enhancements.

RESULTS

A team of utility engineers and national experts is convened to continue the

work of examining the potential for dispersed generation and will report

out how to get another increment of 600 MW this way.

TO BE CONTINUED