A method of controlling an electric output of a wind park, the wind park comprising wind turbines, local wind-turbine controllers, a central wind-park controller, a point of common measurement, and an electric grid connecting the wind turbines and the point of common measurement, wherein grid connections between the wind turbines and the point of common measurement have electric impedances; the method being carried out jointly by the wind turbines with their local wind-turbine controllers and the central wind-park controller, the method comprising: producing electric currents, by the wind turbines, and supplying the electric currents to the electric grid; measuring a value of an electric quantity (V, Q) at the point of common measurement and providing the measurement result to the central wind-park controller; generating, by the central wind-park controller, at least one of a voltage-reference value (V ref) and a reactive-power-reference value (Q ref) for a wind turbine, based on the measured value of the electric quantity at the point of common measurement, and providing the at least one of a voltage-reference value (V ref) and a reactive-power-reference value (Q ref) to the local wind-turbine controller of the wind turbine; causing the wind turbine, by the local wind-turbine controller, to produce at least one of a voltage and a reactive power in the electric grid at the location of the wind turbine which corresponds to the at least one of a voltage-reference value (V ref) and a reactive-power-reference value (Q ref), but which is corrected by a local correction produced by the local wind-turbine controller; wherein the local correction takes into account at least one of a voltage change and a reactive-power change expected at the point of common measurement for the electric current supplied by the wind turbine due to the electric impedance of the grid connection between the wind turbine and the point of common measurement, said electric current taken into account by the correction being determined locally at the wind turbine. producing electric currents, by the wind turbines, and supplying the electric currents to the electric grid; measuring a value of an electric quantity (V, Q) at the point of common measurement and providing the measurement result to the central wind-park controller; generating, by the central wind-park controller, at least one of a voltage-reference value (V ref) and a reactive-power-reference value (Q ref) for a wind turbine, based on the measured value of the electric quantity at the point of common measurement, and providing the at least one of a voltage-reference value (V ref) and a reactive-power-reference value (Q ref) to the local wind-turbine controller of the wind turbine; causing the wind turbine, by the local wind-turbine controller, to produce at least one of a voltage and a reactive power in the electric grid at the location of the wind turbine which corresponds to the at least one of a voltage-reference value (V ref) and a reactive-power-reference value (Q ref), but which is corrected by a local correction produced by the local wind-turbine controller; wherein the local correction takes into account at least one of a voltage change and a reactive-power change expected at the point of common measurement for the electric current supplied by the wind turbine due to the electric impedance of the grid connection between the wind turbine and the point of common measurement, said electric current taken into account by the correction being determined locally at the wind turbine.