Wind Energy

There are several reasons why ARTeMIS software for Operational Modal Analysis (OMA) is a popular tool in wind turbine applications.

Design Verification and Optimization

First of all, there is a growing need to know the dynamic behavior of wind turbines under the right operational conditions when the true environmetal forces are acting on the structure. This need is caused by the rapid development in the dimensions of the turbines. The larger the dimensions get the lower the dynamic behavior in frequency gets. This put the numerical models under pressure and there natural becomes a need for experimental verification of these. In some cases it is even required to follow an experimental study with an updating of the numerical models.

Secondly, sub-parts such as blades and tower are typically having well documented dynamic characteristics that are provided independently of each other. However, problems arises when these subparts are integrated with e.g. the nacelle and the foundation. The integration of course has a serious impact of the dynamic behaviour of the subparts. In order to study this impact OMA is the natural tool to make use of. See e.g. the case study of the FE model updating of the Fuhrländer AG 2.5 MW wind turbine. OMA will return results for the complete turbine behavior under the right environmental conditions. This makes it possible to update numerical models of the complete turbine to behave correctly under the operational conditions of the test.

Easier Documentation of Sub Parts Dynamic Behaviour

Dynamic characterization has been applied in sub part testing in case of e.g. blades. A popular approach has been a free response testing scheme where each mode of the blade is determined in a single test by applying excitation in carefully selected locations of the blade. This is a very costly way of testing as it is time consuming, and there is a potential risk that multiple modes are excited at the same time which consequently will polute the results. In this case, OMA has made life easier for several test institutions. The reason is that all modes now accurately can be determined from a single test.

Now it is Possible to do Modal Analysis on Rotating Machinary during Operation

The presence of rotating components "harmonics" in the data has for years been a nightmare to deal with. In many applications where rotating machinary is present in the structure being tested, it has been necessary to switch of the rotation while doing the modal analysis or it has been necessary to rely on the use of operating deflection shapes (ODS). However, ARTeMIS is born with the ability to handle "harmonics" from rotating components, such as motors, pumps, propellers, wind turbines and generators. With its sophisticated harmonic detection techniques and the advanced time domain estimators called Crystal Clear Stochastic Subspace Identification (CC-SSI) the extracted modal parameters will always describe
the true operating state of the tested structure.