Methods and systems for controlling a wind turbine generator in response to a frequency deviation

A method for controlling active power output of a wind turbine generator in response to a frequency event on a power network to which the wind turbine generator is connected, wherein the active power output of the wind turbine generator is limited to be below an upper active power limit and/or above a lower active power limit, the method comprising:

• determining and dispatching active power references to a controller of the wind turbine generator for controlling the wind turbine generator,
• wherein, during the frequency event, in which the frequency level of the power network is outside a frequency deadband, the active power references are determined based on a measured frequency of the power network;
• and
• wherein, after the frequency event, in which the frequency level of the power network is within the frequency deadband, the active power references are determined to change from a restart active power value to a baseline active power value according to a ramp rate limit, the restart active power value being determined based on a measured active power output of the wind turbine generator.

A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the an operation for controlling active power output of a wind turbine generator in response to a frequency event on a power network to which the wind turbine generator is connected, wherein the active power output of the wind turbine generator is limited to be below an upper active power limit and/or above a lower active power limit, the operation, comprising:

• determining and dispatching active power references to a controller of the wind turbine generator for controlling the wind turbine generator,
• wherein, during the frequency event, in which the frequency level of the power network is outside a frequency deadband, the active power references are determined by:
• determining an active power value based on a measured frequency of the power network;
• comparing the determined active power value with one of the upper active power limit or the lower active power limit;
• and
• when the determined active power value is outside the limit the active power reference is set equal to the limit, or when the determined active power value is not outside the limit the active power reference is set as the determined active power value;
• wherein, after the frequency event, in which the frequency level of the power network is within the frequency deadband, the active power references are determined to change from the final value during the frequency event to a baseline active power value according to a ramp rate limit.