The present invention concerns a method of operating a wind power installation comprising an electric generator drivable by a rotor for outputting electrical power to an electrical consumer, in particular an electrical network. The invention further concerns a wind power installation comprising a rotor and an electric generator coupled to the rotor for outputting electric power to an electrical consumer, in particular an electrical network. The object of the present invention is to provide a method of operating a wind power installation, and a wind power installation, which avoid the disadvantages of the state of the art and in particular avoid voltage over-fluctuations at the consumer, in particular an electrical network, and unwanted shut-down of the wind power installation. In a method of the kind set forth in the opening part of this specification, that object is attained by the invention in that the power delivered to the network by the wind power generator is regulated in dependence on the applied network voltage of the power supply network.