Arrowhead  Weston Transmission Line Project Dave Van House Minnesota Power

Description & Overview  220 mile 345,000 volt electric transmission line  Approved by the Minnesota and Wisconsin regulators in 2001  Construction Began in Minnesota February 2004  Construction to Begin in Wisconsin Fall 2004  Construction scheduled to be completed in 2008

Why was it proposed? Reliability!!  Improves Regional System Security  Provides Maintenance & Operational Flexibility  Allows Customers Greater Access to Generation Sources

Minnesota  Minnesota’s electric network is tied to neighboring states.  If Wisconsin has a problem, Minnesota has a problem.  Minnesota Power customers have been knocked off line by electric system disturbances related to the weak Minnesota- Wisconsin connection.

Recent Regional Problems  June 11, 1997  June 25, 1998  June 10, 1999

IMPACT OF June 25, 1998 DISTURBANCE  IN MAPP ■ 60+ TRANSMISSION LINES TRIPPED ■ 4,000+ MW OF GENERATION LOST ■ More Than 39,000+ CUSTOMERS AFFECTED  IN NW ONTARIO ■ BLACK OUT TO 113,000 CUSTOMERS ■ 650 MW OF LOAD LOST ■ 270 MW OF Generation Lost

Wisconsin Actions  1997 events raise concerns about electric supply reliability in Wisconsin  Wisconsin utilities and regulators form Wisconsin Reliability Assessment Organization (WRAO)  WRAO forms engineering group to study alternatives - WIRES group

PERFORMANCE EVALUATION  DETAILED POWER FLOWS SIMULATION  GENERATOR RESPONSE  DYNAMIC STABILITY  VOLTAGE STABILITY  IMPACT ON MAPP  CONSTRUCTION COSTS  LOSS EVALUATION

Power Flow Analysis  Reactive Voltage Support Requirements  Steady State Maximum Transfer capability  Sensitivity to Modeling Assumptions  Transmission System Loss Analysis

Generator Response  Mechanical Stress on Weston Generator Shaft ■ Large Phase Angle Across MAPP MAIN Interface ■ Eau Claire Arpin Line Switching ■ Instanteous change in Power output

Dynamic Stability  Ability of Systems Generators to remain synchronized and recover from Major System Disturbance  MAPP WUMS Disturbances  Loss of New Facilities  Impact on Existing Limiting Conditions  Dynamic Reactive Support Requirements

Voltage Stability  Ability of the System to Maintain Adequate Voltage Following a Disturbance  Without Adequate Voltage Support System can Experience ■ Increased Current Demand (P = VI) ■ Slowly Declining Voltage ■ Loss of Voltage Sensitive Loads ■ Voltage Collapse

Engineering to Support Permitting  Calculation of; ■ AUDIBLE NOISE ■ ELECTRIC FIELD ■ MAGNETIC FIELD  Analysis of Potential Farm Impacts ■ Stray Voltage ■ Earth Currents

 Magnetic Field  Electric Field  Spark Discharge  Multiple Routes  Multiple Structures  Multiple Circuits  Multiple Flows  Future Years EMF Issues

Transmission Line Noise  Due to Corona Discharge ■ Electric Field at surface of the conductor exceeds the breakdown strength of air ■ Generates light, audible noise radio noise and energy losses  Mitigation ■ Increase Conductor Surface area Larger Conductors Multiple conductors

Substation Noise Monitoring  Long Term  Short Term  Existing Equipment  Impact of Additions

Arrowhead Substation Noise

Other Engineering Issues  Differential GPS Interference ( Precision Farming )  Electric & Magnetic Field ■ Impacts on Pacemakers and implantable Defibulators ■ Impacts on Railroad, Pipeline and AM Radio Transmitter sites

Opposition to the project: l Save Our Unique Lands l Citizens Utility Board l Wisconsin Environmental Decade l North American Water Office l Hillside Dairy l World Organization of Landowner Freedom

Common Utility Corridor

Visual Impact Of Crossing

Existing 161 kV H-Frame

954 ACSR 2-Conductor Bundle with Shield Wire

Single 3M Composite Conductor

Post Permit Studies  Equipment Specification  Construction Support Analysis  Operating studies

Equipment Specifications  Transient studies ■ Breaker Switching Duties Shunt Reactor Shunt Capacitor 345 & 230 kV line breakers ■ Capacitor Bank Switching Issues Voltage Magnification ■ Insulation Coordination Surge Arrester rating & placement Equipment BIL requirements Line Insulation

Construction Impact Studies  Constructability ■ Line outage concerns ■ Maintenance issues ■ Ownership Issues  Increased Cost  Landowner Opposition

Operating Studies  Determination of Operating Limits ■ Reactive Support Requirements Shunt Capacitor location optimization ■ Line Loadability Issues System Intact and Post Contingency ■ Phase Shifter Requirements Line load sharing optimization Post Contingency requirements ■ New Flow-Gate Limits System Intact and Post Contingency

Summary  Operating experience has shown there is a significant risk to electrical reliability in the upper Midwest and Wisconsin  Engineering study commissioned through Assembly Act 204  WRAO recommendation Arrowhead Weston 345 kV Line

Summary  The Arrowhead-Weston Project will substantially alleviate the reliability problems being experienced due to the weak electrical tie between the upper Midwest and Wisconsin.  It will also provide import capability for Wisconsin to meet its emergency power supply requirements.