The invention relates to a method for feeding electric power from at least one wind power installation or of a wind farm into an electric supply system having a line voltage and a grid frequency, wherein the method for feeding electric active power and electric reactive power is prepared and the active power that is fed in can be adjusted by means of an active power control as a function of a grid state and/or the reactive power that is fed in can be adjusted by means of a reactive power control as a function of at least one grid state and the active power control or the reactive power control respectively specify a target value that is to be fed in, which value is adjusted by means of an adjustment function as a function of at least one grid state, wherein the adjustment function is specified with the help of points of support, which points are defined by pairs of values each of which comprise a value for the active power or the reactive power respectively, and a value for the grid state.