Selectively adopting a grid forming operation mode

A method of controlling a wind turbine or a wind park comprising at least one wind turbine connected to a utility grid for utility grid support, the method comprising:

• receiving a control command from a utility grid manager;
• and
• controlling the at least one wind turbine according to a mode selected by the control command, wherein the control command indicates the at least one wind turbine to switch immediately or at a future time interval or a future point in time, to a grid forming mode of operation, the grid forming mode of operation comprising:
• measuring voltage and a current at an output terminal of a grid side power converter;
• calculating a power output from the grid side power converter based on the voltage and the current;
• deriving, by a power controller, a representation of a utility grid frequency based on the power output;
• deriving a frequency error between the representation of the utility grid frequency and a nominal utility grid frequency;
• deriving a grid side power converter control signal based on the frequency error;
• and
• controlling the grid side power converter based on the grid side power converter control signal.