Method for rebuilding an electric supply grid

A method for rebuilding an electric supply grid of a grid operator by means of at least one wind power installation, wherein the electric supply grid has a first grid section and at least one further grid section, wherein the first grid section is connected to the at least one wind power installation and has a first grid nominal voltage, the first grid section is coupled to the at least one further grid section via at least one switching device in order to transmit electric energy between the grid sections, wherein the at least one switching device is set up to disconnect the first grid section from the at least one further grid section in the event of a fault, comprising the steps of operating the at least one wind power installation in an observation mode if the fault occurs, wherein the wind power installation does not feed the first grid section in the observation road and a status of the first grid section is checked, and operating the at least one wind power installation in a grid rebuilding mode if the first grid section has a grid rebuilding voltage, and operating the at least one wind power installation in a normal operating mode again as soon as the fault has passed.