Joint project WEAkustik
Model-based control of wind turbines for adaptive optimization of yield and rotor blade noise
- 01.08.2022 to 31.01.2025
- Drive Systems
In Germany’s climate policy, wind energy represents an important strategic component of the energy transition. In contrast to conventional energy sources, the power density of wind energy is significantly lower, which translates into a high space demand. New legal requirements, such as increasing the minimum distance of wind turbines, short WT, to inhabited areas, are shrinking the area that can be economically used for wind energy. The expansion of this key technology of the energy transition is thus becoming increasingly difficult.
One reason for increasing the minimum distance is the noise emission from wind turbines. In order to take into account the legitimate interests of those living near WT, the noise emission of a WT is subject to strict regulations, compliance with which must be ensured by the operator. From the point of view of the plant developer, who can be held liable for the reported acoustic properties, it is therefore essential to characterize the noise emission as precisely as possible in the design phase and to keep it low during operation. The increasing noise protection requirements for the operation of wind turbines thus pose major challenges for operators and manufacturers alike.
Project Goals and Methods
The primary objective of the WEAkustik project is to identify uncertainties in the aeroacoustic design of the rotor blades and to reduce noise emissions from WT in operation. Since the major part of the rotor noise results from different fluid mechanical phenomena at the rotor blade, for example blade tip vortices, trailing edge noise, etc., the uncertainty in the methods used to calculate the flow around the rotor blades must be reduced.
If the aeroacoustic noise emission can be predicted, the developed aeroacoustic methods can not only be used for the design of rotor blades and complete plants, but also provide valuable information for the development of advanced model-based control methods. For these, the conflicting goals of maximizing yield while simultaneously reducing noise and load, which must be described mathematically as well as analyzed and resolved with respect to pratical implementation, represent a significant challenge.
The flexibility gained by model-based control concepts to describe the operating point-dependent load and aeroacoustic situation opens up new potential for optimizing the operation of WT. In order to reduce the occurring loads and the rotor blade noise, the gained aeroacoustic system knowledge shall be applied to the control by deriving control-oriented, order-reduced models. Thus, control interventions in the form of manipulated variables are to be selected in such way that safe – in the sense of the occurring mechanical loads on the system components – and efficient system operation with the lowest possible noise emission is guaranteed and controlled as required.
Innovations and PerspectivesCopyright: © BMWK
Related to the topic of aerodynamics and aeroacoustics, the novelty of the approach proposed here lies in an industry-oriented solution for the aeroacoustic design of rotor blades through the use of vortex lattice methods and panel methods. In contrast to the blade element momentum method, called BEM, these methods require significantly fewer correction models and represent the three-dimensional unsteady flow. In this way, the inherent uncertainty in the calculation of the incident flow of the rotor blades can be reduced compared to the BEM.
The novelty in the field of control engineering is achieved by the fact that the model knowledge, which is used to reconstruct the aeroacoustic noise emission as described before, is also considered in a model-based predictive control. These models extend already established aerodynamic rotor maps by the information of the noise level and go beyond the current state of control-oriented modeling of WT. In contrast to other work and projects that use model-based predictive controls for WT, the focus of this project is the development of a control concept to solve the conflicting goals of yield maximization, load reduction and noise reduction.