ECE 445 Wind Turbine Generator System Design and

ECE 445 Wind Turbine Generator System Design and Characterization Contact: Prof. James Allison (jtalliso@illinois. edu), Tonghui Cui (tcui 3@illinois. edu) ISE department, ESDL: systemdesign. Illinois. edu

Affiliated Research Project: Improvements to Low. Power Wind Energy Systems Large utility-scale wind turbines are cost effective Increases in size tend to reduce levelized cost of energy (LCOE) In some situations, utility-scale turbines are not practical Small-scale turbines (e. g. , 1 -10 k. W Bergey turbines) have high LCOE. • Multi-Year Research Project: Investigate new design and control strategies that could improve LCOE for small turbines, make IP openly available • •

Strategy: Reduce Tower Cost Through Integrated Structural and Control System Design • Structural tower typically comprises ~40% of overall turbine capital cost • Must be designed for long life: resistant to fatigue and other failure modes • We can control the force exerted at the tower tip (generator torque, pitch, yaw) • Tradeoff between energy production and structural health • How much can we reduce tower cost through new control strategies that balance energy production and structural load mitigation? • What generator torque control capabilities can be made available through candidate low-cost generator systems?

Background: Wind Turbine Components

Project Assumptions • We want to capitalize on design synergies between physical and control system elements to reduce LCOE for small-scale horizontal-axis wind turbines (HAWTs) • These HAWTs will be used for charging batteries, and will not be grid-connected • We assume that a more controllable generator can help mitigate structural loads while maintaining effective power production • We would like to design, implement, and characterize a promising generator system architecture (~1 k. W) • Data from test results will then be used by graduate students to determine impact of generator control capabilities on HAWT LCOE reduction via co-design • If needed, a student with mechanical design training may be found to assist with mechanical elements of HIL testbed

Strategy: Generator Field Control • Blade pitch control is impractical for small-scale wind turbines (higher rotational speeds, reduced volume available for mechanical components) • Permanent magnet generators: Low cost, but limited torque control authority (via charger), and limited range of efficient operating states • Generators with a controllable field can better help compensate for the wind speed variation and other factors relevant to power production and structural reliability.

Example HIL Architecture 1: Separately Excited DC Generator Field Control RPM/Torque Charger DC motor Mechanical Coupler Separately excited DC generator Battery

Example HIL Architecture 2: Automotive Alternator Mechanical Coupler DC motor Simulate Rotor + Transmission Field Control Excitation field current DC charging current Charger Battery Rectifier

Project Objective and Expected Deliverables Objective: Design a controllable electrical generator system for small-scale (1 -10 k. W) wind turbine power generation, and test system characteristics in the context of balancing energy production performance and structural loads. Expected Deliverables • Specify HIL system architecture details (based on either an alternator or separately-excited DC generator) • Select devices for purchase (if commercially available); if any devices needed are not commercially available (e. g. , custom field controller, charger, etc. ), design them • Design the field controller for the reference tracking problem needed for HIL testing (appropriate input trajectories will be provided) • Verify overall system design via simulation • Lab-scale physical implementation, testing, and characterization of this architecture. • Recommendations for possible improvements to system design