Modelling of multi-megawatt wind turbines for EMI and EMS investigations by a topological approach
Todays installed multi-megawatt wind turbines (WT) form highly diverse system due to very complex control devices. Thus, special attention has to be paid to the electromagnetic compatibility (EMC) of the wind turbine. This contribution deals with different electromagnetic interference (EMI) and susceptibility (EMS) effects within the wind turbine. A well-known susceptibility problem of constructions and buildings with large vertical dimensions is the threat situation due to lightning phenomena. On the one hand, the high amplitude of the lightning current effects destructions of infrastructure directly. On the other hand, the transient electromagnetic fields caused by this lightning current could lead to disturbances as well as destructions of electronic devices inside the wind turbine. Furthermore, common-mode currents ¡cm on the power lines between the generator and the frequency converter will cause EMI effects during the normal operation mode. These I cms lead to radiated emissions to the WT's environment as well as to transient disturbing fields inside the WT, which might interfere with the control unit (CU) and the condition monitoring system (CMS). These issues will be investigated in this contribution. Therefore, the electromagnetic topology (EMT) will be applied to the wind turbine. The EMT delivers useful information in order to increase the WT's susceptibility and ensure a high degree of availability.
Measurement Uncertainty of Radiated Electromagnetic Emissions in In Situ Tests of Wind Energy Conversion Systems
Abstract. The electromagnetic (EM) emissions of wind energy
conversion systems (WECS) are evaluated in situ. Results of in situ tests,
however, are only valid for the examined equipment under test (EUT) and
cannot be applied to series production as samples, as the measurement
uncertainty for in situ environment is not characterized. Currently
measurements must be performed on each WECS separately, this is associated
with significant costs and time requirement to complete. Therefore, in this
work, based on the standard procedure according to the “Guide to the
Expression of Uncertainty” (GUM, 2008) the measurement uncertainty is
characterized. From current normative situation obtained influences on the
measurement uncertainty: wind velocity and undefined ground are evaluated.
The influence of increased wind velocity on the measurement uncertainty is
evaluated with an analytical approach making use of the dipole
characteristic. A numerically evaluated model provides information about the
expected uncertainty due to reflection on different textures and varying
values of relative ground moisture. Using a classical reflection law based
approach, the simulation results are validated. Thanks to the presented
methods, it is possible to successfully characterize the measurement
uncertainty of in situ measurements of WECS's EM emissions.

EMC ’ 09 / Kyoto How Large is a Large EuT ? Influence of the DM-CM Conversion to Radiation
The contribution to radiation of wires and cable, which are attached to equipment under test (EuT), will be discussed in this paper. Based on [1], where the effects of single , not intentional feeded wires like antennas have been discussed, now the effects of active driven symmetrical lines like power cables and data lines shall be investigated. Rules of thumbs to convert emission measurements performed on alternative test sites to standard Open Area Test Sites (OATS) will be given in this paper.