A method for feeding electrical power into an electrical supply network by means of at least one wind farm respectively connected to the supply network via a network connection point, wherein the supply network is to be operated at a network frequency, and each wind farm has a plurality of wind power installations, comprising the steps of determining whether the electrical supply network is operating, starting the at least one wind farm in a black-start mode for the purpose of producing electrical power for feeding into the supply network if the supply network is not operating, operating the at least one wind farm in black-start operation in which electrical power is fed into the supply network and the supply network is operated thereby, wherein the network frequency is specified by the feeding-in of the electrical power in the black-start mode and/or during black-start operation.