This work evaluates the impact of large scale integration of wind power in future power systems when 50% of load demand can be met from wind power.The focus is on active power balance control,where the main source of power imbalance is an inaccurate wind speed forecast.In this study,a Danish power system model with large scale of wind power is developed and a case study foran inaccurate wind power forecast is investigated.The goal of this work is to develop an adequate power system model that depictsrelevant dynamic features of the power plants and compensates for load generation imbalances,caused by inaccurate wind speed forecast,by an appropriate control of the active power production from power plants.