Validation of the NewGust approach

The gust events described in the IEC-standard are formulated as coherent gusts of an inherent deterministic character, whereas the gusts experienced in real situation are of a stochastic nature with a limited spatial extension. This conceptual differencemay cause substantial differences in the load patterns of a wind turbine when a gust event is imposed.

Methods exist to embed a gust of a prescribed appearance in a stochastic wind field in a consistent way. The present report deals with the verificationof a synthetic wind field resulting from such a model - the NewGust model. The NewGust model is restricted to gust events associated with the longitudinal turbulence component, and consequently no attention is paid to wind direction gusts.

Theverification is performed by analysing existing measurements of wind speed gust situations and associated structural loads on a Vestas V39 turbine, and subsequently to compare these with analogues simulations applying the NewGust method in order toestablish a (synthetic) gust loading. Eight load cases, representing four mean wind speed regimes that reflect different control characteristics, have been analysed.

Attention has been paid to select the largest possible gust events, associated with eachof the mean wind ranges, within the available data material. The work reported makes part of the project “Modelling of Extreme Gusts for Design Calculations ” (NEWGUST), which is co-funded through JOULEIII on contract no.

JOR3-CT98-0239.