Design of a scaled wind turbine with a smart rotor for dynamic load control experiments

Abstract

The ever increasing size of wind turbines poses a number of design issues for the industry, like increasing component mass and fatigue loads. An interesting concept for reducing fatigue loads is the implementation of spanwise distributed devices to control the aerodynamic loading along the span of the blade, thus mitigating fl uctuations in loading and adding damping to the blade modes. This is usually referred to as the smart rotor concept. In the design of such a rotor, as compared to a traditional one, the integration of sensors and actuators poses additional design challenges. In the research discussed in this paper, a scaled smart rotor was designed and constructed to study its fatigue load reduction potential. A 1.8 m diameter rotor was manufactured and equipped with trailing-edge fl aps. The fl aps were based on piezo electric Thunder actuators that allow for high-frequent actuation. The dynamic strain behaviour of the blade was analysed for optimal placement of the sensors. Several sensors that record the strains and accelerations at different locations along the blade were implemented, but the controller was based on a piezo electric strain sensor. The rotor blades were mounted on a small turbine in the Delft University's Open Jet Facility wind tunnel and a mathematical state space model was obtained by using dedicated system identifi cation techniques. Single-Input Single-Output, Multi-Input Multi-Output H ∞ feedback and feedforward controllers were designed, each focusing on different parts of the load spectrum. The rotor was tested at 0 and 5° yaw angles, with and without load control. A signifi cant reduction of the dynamic loads was attained.

Horizontal Axis Wind Turbine Blade Design Methodologies for Efficiency Enhancement—A Review

“…A smart rotor can sense the strain and acceleration which can then be used to control the loading in spanwise direction. The fatigue load reduction potential of a smart rotor was explored by Hulskamp et al [155] experimentally by scaling down the rotor. The results showed that a significant dynamic load and fatigue losses could be reduced if the coupling between the different blades has been taken care of by the controller.…”

Wind tunnel tests with combined pitch and free-floating flap control: data-driven iterative feedforward controller tuning

“…Aerodynamic and structural details of the blade design can be found in Hulskamp et al (2011). However, as the wind tunnel experiments will also incorporate blade pitch control, the torsional inertia of the blades was reduced by scaling down the root chord by 30 %.…”

Development of a Wind Turbine Test Rig and Rotor for Trailing Edge Flap Investigation: Static Flap Angles Case

“…The dynamic behaviour of the rotor was designed to reflect that of the Upwind 5MW reference turbine [8]. The following equation was used for dynamic scaling [10]:…”

“…In an experimental study, Hulskamp et al [10] designed a two-blade 1.8m diameter rotor that reflects the dynamic behaviour of the Upwind reference [8] turbine using non-dimensional scaling. Strain gages were used to measure the flapwise bending moments.…”