Impacts from large scale integration of wind energy farms into weak power systems

In this paper dynamic aspects related to integration of wind farms into the power system are investigated. A case is considered where a hydro plant is located in the area of the wind farm. Interaction between the wind farm and the hydro power plant is given attention. Flicker contribution from the wind farm has been examined. The importance of considering the degree of synchronisation of power variations from individual windmills has been discussed. The exciter operation of the nearby hydro plant was found to have limited influence on the flicker results, thus representing the grid with a system impedance would be of sufficient accuracy for the investigation of flicker for this case. During transient situation it has been shown that disconnection of some windmills can be necessary to recover a stable operation of the power system. The results of the simulations are highly dependent on the type of models used, and they show that a representation of the turbine shaft is of high importance.