System comprising a wind turbine and method for operating the system
A wind turbine system and to a method for operating said system is disclosed. The system further comprises a detection device configured for detecting body waves generated by an earthquake. In one aspect, the present disclosure is directed to a system comprising a wind turbine, in particular to an onshore erected wind turbine, a wind turbine controller for controlling the wind turbine, and at least one detection device, which is connected to the wind turbine controller for transmitting signals. The wind turbine includes at least a rotor having at least one rotor blade, wherein the rotor is rotatably mounted to rotation support means of the wind turbine, and a tower having a top end for supporting the rotation support means and a support end. The detection device is configured to detect and measure earthquake generated primary waves (P-waves). The detection device may include at least one sensor or a plurality of sensors, wherein the sender is configured to detect and/or measure earthquake generated P-waves. Such sensor may be further configured to detect an acceleration caused by the earthquake using a built-in accelerometer and then to calculate and output a synthetic acceleration, and to provide an estimated Japan Meteorological Agency seismic intensity scale (shindo scale) value.
1. 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;
the method comprising:
measuring earthquake generated P-waves;
comparing a measurement of detected P-waves with a first threshold;
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;
determining an impact time of S-waves generated by a same earthquake generating the P-waves;
determining an altering time required for altering the operation of the wind turbine from the operational state into the first safe mode or the shutdown mode without performing active breaking measures; and
applying active braking measures to the rotor when the impact time is shorter than the altering time.
2. The method according to claim 1 , wherein the first reduced power output is dependent on a magnitude of the measurement such that the first reduced power output decreases with an increase of the measurement.
3. The method according to claim 1 , further comprising:
conducting a load assessment of loads applied upon structures of the wind turbine; and
when the load assessment indicates a critical load situation, altering the operational state of the wind turbine into a load safe mode having a reduced power output or into the shutdown mode.
4. The method according to claim 3 , wherein the load assessment comprises an estimation of load values applied upon structures of the wind turbine based on current or estimated operation values of the wind turbine, the operation values including any one or combination of: a power output of the wind turbine; a measured or estimated wind speed; a measured or estimated wind direction; a pitch angle of a pitch system of the wind turbine; a rotational speed of the rotor; a rotational speed of a power generator of the wind turbine; or the measurement of detected P-waves.
5. The method according to claim 4 , further comprising:
comparing the estimated load values with a load threshold; and when the estimated load values exceed the load threshold, altering the operational state of the wind turbine into the load safe mode having the reduced power output or into the shutdown mode.
6. The method according to claim 5 , further comprising:
determining the reduced power output by conducting an estimation based on one or a combination of: a desired maximum load to be applied upon the structures of the wind turbine; or the current or estimated operation values of the wind turbine.
7. The method according to claim 4 , wherein a magnitude of the reduced power output is dependent on a magnitude of the estimated load values such that the reduced power output decreases with an increase of the estimated load values.
8. The method according to claim 1 , wherein the detection device is arranged at: on or in ground adjacent the tower; or in in the support end of the tower, or on or in ground support means on which the support end of the tower is mounted.
9. The method according to claim 8 , wherein the support end of the tower is mounted to the ground support means by fixation devices, the detection device directly mounted to the fixation devices.
10. The method according to claim 8 , wherein the detection device is configured to determine a propagation direction of the detected P-waves.
11. The method according to claim 1 , wherein the rotation support means comprise a nacelle, the rotor rotatably supported by the nacelle along an essentially horizontal axis of rotation, and the nacelle rotatably mounted about a yaw axis of the wind turbine on the top end of the tower.
12. 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.