The project has developed and verified simulation and prediction models for power fluctuations in large wind farms. The verification is based on ex-tensive measurements in the two large offshore wind farms in Denmark: Horns Rev and Nysted. The models can also be applied to simulation of wind power fluctuations from wind turbines distributed over a larger area than a wind farm. The advantage of the prediction models is that they can be applied in the operation, but these models require a training period be-fore they work in a new system. On the other hand, the simulation model can simulate power fluctuations with possible future wind power develop-ments, based on information about size and location of the individual wind turbines. Thus, the simulation model is a planning tool.