Controlling a wind farm

A wind turbine group having a plurality of wind turbines, comprising:

• a group computer including a group controller configured to control the wind turbine group, wherein each of the plurality of wind turbines generates electrical power as wind turbine power output for feeding into an electrical supply network, wherein the wind turbine group feeds a group power output into the electrical supply network at a grid connection point, wherein the group power output is formed as a sum of a plurality of wind turbine power outputs of the wind turbine group, and the group controller is configured such that:
• a maximum group power output is specified for limiting the group power output;
• a control value for compliance with the maximum group power output is sent to each wind turbine of the wind turbine group to limit the respective wind turbine power output of the respective wind turbine to a maximum value defined by the control value;
• a control relationship is determined as a relationship between potential control values and potential group power outputs, in order to specify the control value, and the control value is determined using the control relationship, and depending on the maximum group power output;
• and
• the control relationship is stored as a table of value tuples, wherein:
• each value tuple includes a potential control value and a potential group power output, or
• the control relationship includes a threshold control value which is representative of an associated control value at which an associated group power output reaches a current maximum value of the associated group power output, and the threshold control value is composed of the associated control value and a reserve value, or
• the control value is specified as a relative value in relation to a nominal power.

A method of controlling a wind turbine group having a plurality of wind turbines, comprising:

• forming a group power output as a sum of wind turbine power outputs of the wind turbine group, wherein each wind turbine of the wind turbine group respectively generates electrical power as a respective wind turbine power output for feeding into an electrical supply network;
• feeding, by the wind turbine group, the group power output into the electrical supply network at a grid connection point;
• specifying a maximum group power output for limiting the group power output;
• to comply with the maximum group power output, sending a control value to each wind turbine of the wind turbine group for limiting the respective wind turbine power output to a maximum value defined by the control value;
• determining a control relationship between a plurality of potential control values and a respective plurality of potential group power outputs to specify the control value, wherein the control value is determined using the control relationship and the control value is determined depending on the maximum group power output;
• and
• to determine the control relationship successively for the plurality of potential control values, from a predefinable first potential control value to a predefinable last potential control value, calculating a respective potential group power output for a respective potential control value, wherein:
• the potential group power output for the respective potential control value is calculated as a sum of power outputs that are capable of being generated by each of the wind turbines of the wind turbine group, and
• a power output capable of being generated by a wind turbine is calculated depending on
• a nominally limited power output which is calculated using a nominal power of the wind turbine and the potential control value, and
• an available power output denoting an electrical power output which can currently be generated by the wind turbine.