The opening of the first German Offshore Wind farm alpha ventus fired the wind industry's imagination. Since the conditions are rough and the reachability is limited out at the sea, wind turbines that were designed for these dynamic loads can assure high availability and therefore profitability.
Fatigue is one of the key design drivers for the design of rotor blades of offshore wind turbines. For larger rotor blades, the swept area increases with the square of the rotor diameter. However, the weight of the blade increases to the third power. Therefore, in-depth knowledge about the failure mechanisms of materials is necessary.
Stefan Wessels, Project engineer at the competence center rotor blades of Fraunhofer IWES presents the results of a detailed fatigue analysis of rotor blades considering non-linear Goodman analysis combined with finite element analysis. "Considering the material properties more in depth and using their capacities, lead to a weight reduction without a reliability reduction", states Wessels.
Not only the material, also the assembly of rotor blades is a critical point that needs profound investigation to as-sure blade design optimization, especially for larger blade lengths. Since the composite parts of a rotor blade are bonded together, the adhesives play a key role in the structure. Stefan Wessels presents a beam scaled test for the evaluation of the structural adhesive bond between the web and spar cap of a MW scale wind turbine blade. In contrast to coupon size testing for the mechanical characterization of the bonding paste, this method takes into account the shape of the bonding line, material thickness variability and the stochastically distributed voids, and above all a more realistic stress distribution in the bond line.
In 2009 about 24 GW of installed wind power capacity was integrated into the German power supply system. The system operator requires accurate and reliable forecasts of the electricity generated by wind turbines for the next hours to days ahead. Fraunhofer IWES works on the development of advanced shortest-term predictions in order to improve accuracy of wind power forecasts, and models for estimations of the forecast uncertainty. "Improved ac-curacy of wind power forecasts in combination with estimations of the forecast uncertainty does not only lead to higher system security but also to attractive cost savings concerning the allocation of balancing power", declares Jan Dobschinski, researcher for signal analysis, model de-velopment and prediction systems at Fraunhofer IWES.
One approach to enable high penetration of wind power is for wind farms or wind farm groups to be operated as far as possible as conventional power plant. "In the German "Renewable Model Region Harz" (RegMod-Harz) wind farms and other renewable energy producers, controllable consumers and energy storage devices will be coupled to a large virtual power plant (VPP)", reports Dr. Kurt Rohrig, head of division Energy Economy and Grid Operation. Beside scheduled energy supply, the VPP will provide ancillary services like frequency and voltage control to ensure the reliability of the power system.
IWES researcher Stefan Faulstich shows that electrical subassemblies are a significant contributor to wind turbine unreliability and the resulting consequences for maintenance procedures. By evaluating empirical data the "reli-ability based maintenance strategy" may identify weak points, find fault propagations and predict remaining life time to optimise maintenance. Therefore, detailed documentation of all maintenance measures and a purposeful structured database are necessary.
A shortest-term wind power prediction with integration of offsite wind speed measurements was presented by Dr. Bernhard Lange, Head of information and prediction systems at Fraunhofer IWES. This forecast of wind power is needed for balancing the feed in of wind power in the electrical grid. Therefore a large effort is done to improve the quality of the forecast and their availability.
In the present study the use of offsite measurements for forecasting is investigated for two aims: To improve the forecast quality, especially at high power classes and to guarantee a high quality forecast even if other input parameters of the forecast system, like actual power measurements, are missing. This forecast system is currently installed at three of four German TSOs.
Britta Rollert | Fraunhofer
Lade-PV Project Begins: Vehicle-integrated PV for Electrical Commercial Vehicles
03.04.2020 | Fraunhofer-Institut für Solare Energiesysteme ISE
Harnessing the rain for hydrovoltaics
03.04.2020 | Max-Planck-Institut für Polymerforschung
Drops of water falling on or sliding over surfaces may leave behind traces of electrical charge, causing the drops to charge themselves. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz have now begun a detailed investigation into this phenomenon that accompanies us in every-day life. They developed a method to quantify the charge generation and additionally created a theoretical model to aid understanding. According to the scientists, the observed effect could be a source of generated power and an important building block for understanding frictional electricity.
Water drops sliding over non-conducting surfaces can be found everywhere in our lives: From the dripping of a coffee machine, to a rinse in the shower, to an...
90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous
An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...
The bacteria that cause tuberculosis need iron to survive. Researchers at the University of Zurich have now solved the first detailed structure of the transport protein responsible for the iron supply. When the iron transport into the bacteria is inhibited, the pathogen can no longer grow. This opens novel ways to develop targeted tuberculosis drugs.
One of the most devastating pathogens that lives inside human cells is Mycobacterium tuberculosis, the bacillus that causes tuberculosis. According to the...
An international team with the participation of Prof. Dr. Michael Kues from the Cluster of Excellence PhoenixD at Leibniz University Hannover has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.
A 15-member research team from the UK, Germany and Japan has developed a new method for generating and detecting quantum-entangled photons at a wavelength of...
Together with their colleagues from the University of Würzburg, physicists from the group of Professor Alexander Szameit at the University of Rostock have devised a “funnel” for photons. Their discovery was recently published in the renowned journal Science and holds great promise for novel ultra-sensitive detectors as well as innovative applications in telecommunications and information processing.
The quantum-optical properties of light and its interaction with matter has fascinated the Rostock professor Alexander Szameit since College.
02.04.2020 | Event News
26.03.2020 | Event News
23.03.2020 | Event News
03.04.2020 | Materials Sciences
03.04.2020 | Life Sciences
03.04.2020 | Life Sciences