Method for feeding electrical power into an electrical supply network

A wind power installation, wind farm, electrical energy store or combination thereof, wherein the wind power installation, wind farm, electrical energy store or combination is converter-controlled, for exchanging electric power with an electricity supply grid that has a grid frequency at a grid connection point, comprising:

• a converter configured to exchange the electric power depending on a control function, wherein the electric power includes active power and reactive power;
• and
• a controller configured to control the exchange of the electric power using the control function, wherein the control function controls the electric power depending on at least one state variable of the electricity supply grid, and wherein the controller is configured such that:
• switching between a normal control function and a support control function, different from the normal control function, as the control function is permitted,
• the normal control function is used when it has been determined that the electricity supply grid is operating stably, and
• the support control function is used when a grid problem, grid fault or an end of the grid fault has been detected,
• wherein:
• the support control function controls fed-in power to counteract an oscillation in the electricity supply grid of a synchronous generator connected to the electricity supply grid or caused by the synchronous generator, and
• the support control function is used as the control function in post-fault behavior, wherein the post-fault behavior is a voltage recovery at the grid connection point following a voltage drop at the grid connection point.