1 TRANSMISSION SYSTEM OVERVIEW NETWORK OPERATING COMMITTEE April 17, 2007 New Mexico Transmission System Overview

2 Efficient Use of Existing Transmission System  Long-term weather study ( 8 weather stations)  Increased rating (18%) of transmission lines by using less conservative wind speed assumptions  Real-time monitoring  Installed monitoring equipment to allow for temporary increase of emergency ratings based on actual (as opposed to worst- case) temperature and wind conditions  Traveling Wave Fault Recorders on all 230kV, 345kV line and key 115kV lines  Disturbance Monitors  Bulk transformer online monitoring (oil, temperature, hot spots)  Risk management ( Video Sagometers)  Several lines exposed to low-probability, short-duration events have been rated for high-temperature operation

3 Efficient Use of Existing Transmission System

4  Reactive Compensation & Voltage Support  Series compensation of 345 kV lines  Shunt capacitors  Albuquerque power factor control (RCCS)  Transmission Line Clearance  Over 1500 miles of transmission lines have been phase-raised to remove ground clearance limitations.  Emergency Procedures  Automatic load shedding schemes, as safety net measures, to handle deficiencies in transmission capability during peak usage during scheduled maintenance and forced repairs  Reactor contingency scheme

5 WECC/NERC Criteria Planning and Operations Criteria WECC/NERC Standards Current System Capability with All Lines in Service (N-0)  All facilities within normal rating limits  Voltage levels shall be within normal limits  Network stability shall be maintained  All customer demands shall be supplied and all firm transfers shall be maintained Current System Capability with one line out of Service (N-1)  All facilities within emergency ratings  No bus voltage drop greater than 5%  5% Real and Reactive Power Margins  Transient voltage dip should not exceed 20% for longer than 0.33 sec  Transient frequency dip should not exceed 59.6 Hz for longer than 0.1 sec Current System Capability with two Lines out of Service (N-2)  All Facilities within emergency ratings  No bus voltage drop greater than 10%  2.5% Real and Reactive Power Margins  Transient voltage dip should not exceed 20% for longer than 0.67 sec  Transient frequency dip should not exceed 59.0 Hz for longer than 0.1 sec

6 Generation Interconnections A Few Facts  Received 50 generation interconnections since 2000 (42 direct interconnect and 8 are joint studies)  Signed 6 LGIA for a total of 768 MW  451 MW Wind  317 MW Gas and Bio Mass  Today’s Queue  5 Feasibility Studies  6 System Impacts Studies  4 Facility Studies  1562 MW Wind  1479 MW Gas and Combined Cycle

7 New Mexico Wind Energy Center  Located in Eastern New Mexico  204 MW capacity  Supplies up to 20% of PNM’s total demand at any given time  Supplies approximately 3.5% on the average  Installed in 2003, in record time!  Owned and operated by FPL Energy  PNM purchases & markets all the output

8 Technical Specifications  136 towers, each 210 feet tall  Base circumference is > 40 feet!  Wind Farm spread out over 15 miles  Three blades at top of each tower, each 110 feet in length  Facility feeds power onto nearby PNM high-voltage transmission line

9 How Wind Turbines Produce Energy  Blades rotate toward the wind  Winds of 6 to 7 mph are enough to turn blades  Blades turn a shaft connected to the rotor of an electric generator  Mechanical components can withstand winds of up to 55 mph Person on top of rotor

10 NMWEC Power Output Pattern PNM Load Pattern (08/03-08/04) Winter Peak Load Spring/Fall Load Valleys Summer Peak Load

11 Questions?