Wind turbine blade certification tests often generate sudden audible cracking sounds from somewhere within the blade, without the operators being able to locate the noise source or to evaluate the existence or the extent of any damage. It would be beneficial to be able to detect any damage incurred by the blade, whether it is accompanied by audible noise or not. The current project, named AEGIS, is looking at the possibility of using acoustic emission monitoring during testing of fiber composite blades to detect the source of damage events and assess the blade condition. The test methodology is discussed in the context of the blade certification procedure and results are presented from a series of static and fatigue blade tests to failure in the laboratory.
Wind turbine blade certification tests, comprising a static test, a fatigue test, and finally a residual strength test, often involve sudden audible cracking sounds from somewhere within the blade, without the operators being able to locate the noise source, or to determine whether damage (minor or major) has occurred. A current EC-funded research project is looking at the possibility of using acoustic emission (AE) monitoring during testing of fibre composite blades to detect such events and assess the blade condition. AE can both locate and characterise damage processes in blades, starting with non-audible signals occurring due to damage propagation at relatively low loads. The test methodology is discussed in the context of the blade certification procedure and results are presented from a series of static and fatigue blade tests to failure in the laboratory. Inferences are drawn about small differences in the manufacture of the nominally identical blades and conclusions are presented for the application of the methodology.
The paper describes a method for the reliability and safety assessment of wind turbine control and protection systems. This enables the qualitative and quantitative reliability analysis of these systems and calculates an appropriate set of reliability indices. The method for the probabilistic safety assessment of these systems includes the event-tree approach for identifying all possible unsafe events of wind turbines operation and all scenarios that can lead to them. The Markov procedure is used for the modelling of all failure modes. This method is compatible with the existing respective international safety standards and criteria; it can be used by designers, manufacturers and certification institutes. The analysis of a part of the control and protection system of the CRES wind turbine in Agios Efstratios is also included.
SUMMARYIn this paper, a new splines–based control method for robot manipulators is presented and discussed. The above method can be effectively used for path planning and control of rigid and flexible robots. The computational simplicity of the proposed algorithm, together with its flexibility and its high–level intelligence built in, can be considered as promising tools for achieving the goals of modem robot manipulator design.
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