WindDyS research project

Project title: WindDyS – Development and investigation of a novel dynamic stall model for the preliminary design of wind turbine rotor blades

Objective and reason for the project:

The WindDyS project investigated the dynamic behavior of aerodynamic cross-section profiles of rotor blades for wind turbines. If the angle of attack over which the airfoils are approached is changed dynamically, this can lead to a change in behavior in the area of the stall – the so-called dynamic stall. The WindDyS project has been concerned with simulating this behavior precisely with numerical flow calculations and developing a reliable model with which these calculations can be transferred to industrial load calculations. Until now, adapted models originally developed for helicopter aerodynamics have been used for this purpose. The aim of the project is to use an improved wind energy-specific model to promote the development of longer, lighter and thus also more flexible rotor blades in order to enable the construction of fewer but larger wind turbines in the future and thus conserve the resources required for the energy transition.

Methods and work steps

In the project, extensive numerical flow simulations were carried out for various profile geometries, especially thick ones, which depict their properties under different conditions. The results of the high-resolution flow simulations should be used to create an improved model for the occurrence of dynamic stall on wind energy profiles. Based on the Onera model, an approach was implemented which, with corrections to the Onera model, allows the results of such calculations to be mapped in a simplified and fast model. This provides a necessary second-order approach for mapping the dynamic properties of the dynamic stall. Implementing the second-order model in the open source software OpenFAST requires significant adjustments to the core code, which can be implemented together with the code developer in the future.

WindRamp research project

Project title: WindRamp – Observer-based prediction of grid congestion and possible injection of offshore wind energy for operational grid management and trading processes.

Summary:

Content and Methodology:

The objectives of the WindRamp project are to improve grid operations and optimize electricity trading processes by (i) researching and testing an observer-based short-range forecast of wind farm performance based on lidar wind measurements, (ii) the practical application of this curtailment forecast in grid operation management and electricity trading, and analysis and evaluation of the improvements achieved; and iii) the parallel concept development and demonstration of a compact lidar with significantly increased measurement range and better data availability to extend the temporal forecast horizon. In the subproject Shortening Period Forecast and Offshore Measurement Program, ForWind ‘ University of Oldenburg is conducting an offshore measurement campaign with lidar to provide data for the shortening period forecast. Measurement scenarios and analysis methods are adapted to the targeted high ranges. Based on these data, methods for the prediction of insb. ramp events with time horizons of up to 30 minutes were researched, tested and validated. Together with the project partners, improvements in the application of the new methods for grid operation management and electricity trading will be reviewed. The XXL lidar demonstrator developed in the project will be compared with a commercial lidar.

PASTA research project

Project title: PASTA – Precise design methods of complex coupled oscillation systems of modern wind turbines in turbulent excitation

Summary:

With increasing rotor diameters and hub heights, wind turbines become more susceptible to vibration. As a result, loads from the simulations are often not accurately predicted and consequently cannot be correctly considered in the WT design process. On the one hand, these inaccuracies in the plant design can result in an oversizing of individual components and thus drive up the manufacturing costs or, on the other hand, lead to a too weak design of certain components of the WTG, which in turn results in increased costs for maintenance and repair. Therefore, in order to take the next step towards increasing precision in turbine design, an improved understanding of the effect of the wind field on the load dynamics is essential.

Content and Methodology:

This project is dedicated to the temporary upswing of turbine components, a phenomenon of wind turbines that is often observed but has hardly been addressed so far. This phenomenon typically affects weakly damped plant modes, such as higher tower modes or blade modes. This often involves a periodic excitation that is strongly influenced by the wind field. Within the project, new approaches for the combination of wind field descriptions and a detailed description of the dynamic behavior of the wind turbine in a modern MBS environment are investigated and new simulation methods for robust and accurate design are explored.

WiSAbigdata research project

Project title: WiSAbigdata – Wind farm virtual Site Assistant for O&M decision support – advanced methods for big data analysis.

Summary:

Content and Methodology:

The aim of the ‘WiSA big data’ project is to contribute to the early detection and diagnosis of faults in wind turbines by analyzing operating data with high temporal resolution and thus to support decisions in maintenance planning and implementation. To this end, on the one hand, methods that have proven effective on the basis of 10-minute averaged operating data are being elaborated and tested for application to temporally high-resolution data. On the other hand, novel methods for early fault detection are transferred to wind energy applications. The developed and tested methods are subjected to a practice-oriented quantitative comparative evaluation. Based on this, an automatic selection of the most suitable methods for the respective application is aimed at. For common data management, analysis and evaluation, a general software and hardware platform will be built as the core system for WiSA. Powerful methods will be implemented for industrial use in a WiSA demonstrator to enable predictive maintenance and detailed analysis of operational events. The connection to the core system for WiSA should make it possible to integrate further innovative methods for early fault detection into the WiSA demonstrator in the future, thereby allowing long-term usability.

YawDyn research project

Project title: YawDyn – Validation of yield increases and load reductions in offshore wind farms by adapted dynamic wind direction tracking.

Summary:

Content and Methodology:

For the first method, ForWind is developing stability-dependent yaw control based on SCADA data. Here, the threshold values of the yaw control are dynamically adapted to the current flow conditions. The aim is to optimize the wind direction tracking with respect to the load on the yaw drive and power of the WT for the respective environmental condition. The second method is based on the concept of “passive wake deflection” developed by ForWind. This is being further developed by ForWind and prepared and parameterized for implementation in the WTG control system at the BO1 offshore wind farm. The method reduces the number of yaws of an upstream WT, causing a deliberate slant flow, which deflects the wake, reducing turbulence and shadowing effects on a downstream WT. ForWind will publish the methodological and scientific results and thus contribute to risk minimization in the application of novel methods for aerodynamic wind farm control in the use of offshore wind energy.

X-Wakes research project

Project title: X-Wakes – Interaction of the wakes of large offshore wind farms and wind farm clusters with the marine atmospheric boundary layer

Summary:

The main objective of the X-Wakes project is to record the changes in wind conditions for the operation of offshore wind farm clusters during the large-scale expansion of offshore wind energy use. This is done both by an extensive measurement program with airborne and satellite-based measurements and by LiDAR measurements at various locations within the German Bight. The interactions of wind farm clusters with each other, which will also be investigated in great detail with the numerical tool of large-eddy simulation in addition to the measurements, will be implemented in industrial models and in a mesoscale weather model in order to enable a realistic yield forecast for future expansion scenarios with these.

WinConFat research project

Project title: WinConFat – Material fatigue of onshore and offshore wind turbines made of reinforced concrete and prestressed concrete under highly cyclic loading

Summary:

The overall WinConFat research project aims to experimentally determine and scientifically describe the influences on concrete, reinforcing steel and composite fatigue. These investigations are being carried out by a network of six universities and the Federal Institute for Materials Research and Testing and are being centrally coordinated by the Institute of Concrete and Masonry Structures at Leibniz Universität Hannover.

Together with the results of the overall WinConFat research project, the results of the sub-project carried out by the Institute of Concrete and Masonry Structures enable the further development of the currently valid standardization and thus a significantly more economical design of wind turbines made of reinforced concrete and prestressed concrete in the fatigue limit state. This is initially done by the DAfStb by drawing up a “Guideline for the design of wind turbines made of reinforced concrete and prestressed concrete against fatigue”. Due to the authorization of the DAfStb as a regulatory body, the implementation of the results in a technical rule and its introduction by the building authorities can be expected immediately after the end of the project. It can also be assumed that the findings will be incorporated into European standards and regulations in the medium term. In addition, a more realistic assessment of the remaining service life of existing load-bearing structures is possible.

Ho-Pile research project

Project title: Ho-Pile – Investigations on the horizontal load-bearing behavior of XL monopiles under cyclic loading

Summary:

In the case of a WTG monopile foundation, its steel mass depends heavily on the geotechnical design. This is essentially based on p-y approaches. Due to a lack of verified knowledge, there are no clear or only inadequate specifications in the regulations. Furthermore, no generally recognized and experimentally validated p-y approaches are yet available for geotechnical MP measurements. This results in project uncertainties and often unnecessary additional steel mass consumption. The Ho-Pile research project validates and extends an existing p-y approach. This requires complex numerical FE calculations and experimental investigations on a scale of 1:5. The project is based on a p-y approach for sand that has been developed in recent years. This approach is experimentally validated by tests in the TTH’s foundation engineering test pit.

HiPE-WiND research project

Project title: HiPE-WiND – Multidimensional loads on the high-performance electronics of wind turbines

Summary:

The aim of the project is to investigate the high-performance electronics for wind turbines under real multimodal environmental and load conditions, to research their causes of failure and to develop and experimentally verify concepts for optimizing their robustness. This requires extensive experimental investigations in which entire inverter systems are reproducibly exposed to multimodal loads. The aim of these investigations is to obtain indications of weak points in the system hardware through accelerated ageing and to analyze how inverter service life can be optimized by specifically influencing the electrical loads.

PreciWind research project

Project title: PreciWind – Precise measuring system for non-contact recording and analysis of the dynamic flow behavior of wind turbine rotor blades

Summary: