On the Necessity of Dynamic Inflow

Abstract

This work explores the importance of dynamic inflow for wind turbines of varying rotor radius and also includes various coplanar multirotor setups. A parametrized model including the rotor and inflow dynamics is formulated. Typical values and ranges for the parameters are estimated using theoretical results and empirical data. The model is analyzed in terms of the kinetic energy and its dynamic responses. By analyzing the ratio of kinetic energy in the rotor vs. induced flow, we obtain a scalar measure for the relative importance of the dynamic inflow. Furthermore, the linearized closed-loop dynamics of a wind turbine around its optimum are examined in terms of the eigenvalues and time constants. This gives insights into the stability and control requirements for wind turbine systems. The results show that dynamic inflow should be included in wind turbine modeling and control of most wind turbines, and can only be ignored for small isolated rotors.

Keywords

• scaling
• eigenvalues
• time constants
• wind turbine