Operation and Control
An important design criterion for large wind turbines is to reduce fatigue and extreme loads on the support structure and blades by control. This is a challenging task, because transients such as gusts represent an unknown disturbance to the control system. Conventional feedback controllers can compensate such excitations only with a delay since the disturbance has to pass the entire wind turbine and actuator dynamics before showing its effects in the controller outputs. This usually results in additional loads for the wind turbine and requires high actuator rates. LIDAR (Light detection and ranging) systems are able to provide preview information of wind disturbances at various distances in front of wind turbines. This information can be used to improve control of wind turbines not only to reduce the loads but also to increase their power output.
Wind and waves develop enormous forces on offshore wind turbines. The accumulated fatigue loads on the turbine as a whole are not recorded. However, a continuous monitoring would help to prevent damage and to operate the plant optimized for each individual site. The SWE develops reliable and economical methods for determining the load on key components such as the drive train, tower and blades. For example, neural networks are trained to estimate damage equivalent loads purely from standard operational data of an offshore wind energy plant. No need of elaborate instrumentation! The procedure is still in the testing phase but has been successfully applied to data taken from the test field “alpha ventus”.
Service Life Control
Monitoring and Inspection of Structures At Large Wind Turbines
In the frame of the MistralWind project, which includes the development of a monitoring system for Wind Turbine structures, a control strategy is being designed, that considers the remaining service life.