Optimal control structure to reduce the cumulative load in the drive train of wind energy converters

In principle the variable speed wind energy converters offer the technical possibilities to reduce the cumulative load in the drive train and the influence on the electrical grid. The short time wind power fluctuations on the wind rotor can be smoothed by utilisation of rotating masses as storage of kinetic energy. This requires a special designed automatic control and system management, which minimises electric power fluctuation at maximum energy yield. Based on the named goals, a new control approach has been conceived. These aims are achieved on base of stochastic dynamic optimisation algorithms. The new control approach considers the dynamic of the actual wind speed on the given location via a weight function on one hand and produces a direct action on the cumulative load for the plant's drive train and the time dependent run of the electrical power output curve by the formulation of quality functions on the other hand. The approach was tested with help of simulation and test plant, in which a variable speed wind energy converter with the nominal power of 22 kVA is modulated under consideration of the separate system part's non-linear nature. The results of the new control approach are compared to conventional control methods.