A method for feeding electrical power into an electrical supply grid (50, 120) having a grid voltage having a grid frequency (f N) at a grid connection point by means of at least one wind power installation or a power plant consisting of at least one wind power installation, comprising the following steps: - specifying a reference system having a reference frequency (fref), a reference phasor (Z ref) having a reference angle, and a reference amplitude of an output voltage (U ref) to be generated, wherein the reference angle revolves at the reference frequency and the reference frequency (f ref) substantially corresponds to the grid frequency (f N), - specifying a phase angle (φ) as the phase angle between the output voltage (U ref) and the grid voltage (U N), - calculating an infeed angle, which revolves with the reference angle, from the specified phase angle, such that the specified phase angle (φ) results as a phase angle between an output voltage generated at the infeed angle and the grid voltage when the reference frequency (f ref) corresponds to the grid frequency (f N), - generating the output voltage (U ref) having a voltage amplitude depending on the reference amplitude, a frequency depending on the reference frequency and the infeed angle and - delayed tracking of the behavior of the grid voltage by the reference system, characterized in that for the delayed tracking: - an actual phase angle between the generated output voltage (U ref) and the grid voltage (U N) is detected, - a difference angle between the specified phase angle and the detected phase angle is formed, - the reference angle is changed in such a way that the difference angle is reduced according to the magnitude using a predetermined delay function and - the reference frequency is adjusted to the reference angle changed in this way. - specifying a reference system having a reference frequency (fref), a reference phasor (Z ref) having a reference angle, and a reference amplitude of an output voltage (U ref) to be generated, wherein the reference angle revolves at the reference frequency and the reference frequency (f ref) substantially corresponds to the grid frequency (f N), - specifying a phase angle (φ) as the phase angle between the output voltage (U ref) and the grid voltage (U N), - calculating an infeed angle, which revolves with the reference angle, from the specified phase angle, such that the specified phase angle (φ) results as a phase angle between an output voltage generated at the infeed angle and the grid voltage when the reference frequency (f ref) corresponds to the grid frequency (f N), - generating the output voltage (U ref) having a voltage amplitude depending on the reference amplitude, a frequency depending on the reference frequency and the infeed angle and - delayed tracking of the behavior of the grid voltage by the reference system, characterized in that for the delayed tracking: - an actual phase angle between the generated output voltage (U ref) and the grid voltage (U N) is detected, - a difference angle between the specified phase angle and the detected phase angle is formed, - the reference angle is changed in such a way that the difference angle is reduced according to the magnitude using a predetermined delay function and - the reference frequency is adjusted to the reference angle changed in this way.