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ENGR 340X 2011 Iowa State University. James D. McCalley Harpole Professor of Electrical & Computer Engineering. Wind Energy Basics. Outline. What is a wind plant? Power production Wind power equation Wind speed vs. height Usable speed range Problems with wind; potential solutions.
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ENGR 340X2011Iowa State University James D. McCalley Harpole Professor of Electrical & Computer Engineering Wind Energy Basics
Outline What is a wind plant? Power production Wind power equation Wind speed vs. height Usable speed range Problems with wind; potential solutions
What is a wind plant? Overview
Two kinds of AC generators Synchronous generator Induction generator Stator winding (60 Hz AC) Connects to grid DC, supplied either by external circuit or permanent magnets AC, induced via SLIP between it and stator mag field Rotor winding None (fixed speed machine) Electric control Full converter interface (variable speed) DFIG (variable speed machine)
Synchronous Machine Structure Phase A STATOR (armature winding) ROTOR (field winding) + N Phase B + DC Voltage S The negative terminal for each phase is 180 degrees from the corresponding positive terminal. + Phase C A Two Pole Machine (p=2) Salient Pole Structure
Induction Machine Structure Phase A STATOR (armature winding) ROTOR (Squirrel cage) + Phase B + The negative terminal for each phase is 180 degrees from the corresponding positive terminal. + Phase C
Induction Generators Region of operation Motor operation Generator operation
Electric Generator Type 1 Conventional Induction Generator (fixed speed) Type 2 Wound-rotor Induction Generator w/variable rotor resistance Type 3 Doubly-Fed Induction Generator (variable speed) Type 4 Full-converter interface Plant Feeders ac dc generator to to dc ac full power
Type 3 Doubly Fed Induction Generator • Most common generation technology today • Stator side frequency dictated by grid • Provides variable speed via rotor freq control • Converter rating only 1/3 of full power rating • Eliminates wind gust-induced power spikes • Provides voltage control
Wind turbine Collector Circuit • A distribution system, often 34.5 kV
Existing Transmission + good wind areas (Use Firefox to view http://dec1106.weebly.com/google-earth.html)