Reduced order analytical modelling of micro wind turbine rotordynamics with tower shadow effects

Area of Science:

• Mechanical Engineering
• Renewable Energy Systems
• Vibration Analysis

Background:

• Micro scale wind turbines (μWTs) operate at higher rotational speeds, leading to significant vibration levels compared to larger turbines.
• The direct drive configuration and use of tail vanes for directional control in μWTs contribute to unique dynamic loading conditions, including high yaw rates and gyroscopic loads.
• Existing dynamic analysis tools are often designed for large wind turbines, necessitating specialized investigation into μWT dynamics.

Purpose of the Study:

• To investigate the unique dynamic loading conditions and vibration characteristics of micro scale wind turbines (μWTs).
• To develop a simple mathematical model for better dynamical insights into μWT behavior.
• To identify key design parameters influencing μWT vibrations and propose methods for performance improvement.

Main Methods:

• Development of a simplified mathematical model to analyze μWT dynamics.
• Conducting a parametric study focusing on generator bearing span and rotor center of gravity (CG) position.
• Applying calculated optimal CG placement to an existing μWT design for validation through a case study.

Main Results:

• Increasing the generator bearing span was found to decrease overall vibrations in μWTs.
• Shifting the rotor's center of gravity towards the rear bearing effectively reduced vibrations across most degrees of freedom.
• A case study demonstrated significant reduction in root mean square vibrations following the application of the optimized design parameters.

Conclusions:

• The developed mathematical model provides valuable insights into μWT dynamics, surpassing purely numerical approaches.
• Strategic adjustments to bearing span and rotor CG position are effective in mitigating vibrations in μWTs.
• The findings offer practical guidance for designers to enhance the performance and extend the operational lifespan of micro scale wind turbines.