REACTIVE POWER CONTROLLER FOR CONTROLLING REACTIVE POWER IN A WIND FARM

A reactive power controller 222 for controlling reactive power in a wind farm grid connected to a utility grid and including at least two sub-grids and a collector portion is provided. At least one wind turbine 100 is connected to each sub-grid, wherein the at least two sub-grids are connected to the collector portion and wherein the collector portion establishes the connection to the utility grid. The reactive power controller 222 includes a device for determining an actual reactive power value at the collector portion, and a wind farm controller 202 operatively connected to the device for controlling at least one of said wind turbines 100 on basis of the determined actual reactive power value such that a desired reactive power value is attained.