System comprising a wind turbine and method for operating the system

A method for operating a wind turbine system, the wind turbine system including:

• a wind turbine having a rotor with at least one rotor blade, rotation support means for rotatably supporting the rotor, and a tower having a top end that supports the rotation support means and an opposite support end;
• a wind turbine controller configured to control operation of the wind turbine;
• and
• a detection device in communication with the wind turbine controller for signal transmission therewith, the detection device configured to detect and measure earthquake generated P-waves from ground motions or vibrations with frequencies from 500 Hz to 0.00118 Hz;
• the method comprising:
• measuring earthquake generated P-waves;
• comparing a measurement of detected P-waves with a first threshold;
• and
• when the measurement exceeds the first threshold, altering an operational state of the wind turbine into a first safe mode having a first reduced power output or into a shutdown mode;
• the method further comprising:
• determining a propagation direction of the detected P-waves;
• determining a sensitive direction range of the wind turbine;
• comparing the propagation direction with the sensitive direction range;
• when the propagation direction lies within the sensitive direction range and the measurement exceeds the first threshold, altering the operational state of the wind turbine into a second safe mode having a second reduced power output that is smaller than the first reduced power output or into the shutdown mode.