Laser radar device and wind turbine control system
A configuration is provided which includes: a reference light source to emit laser light; an optical phase modulator to perform phase modulation of transmission light of the laser light on the basis of a linear-phase-modulation signal having a first frequency component and a second frequency component; an optical intensity modulator to modulate light intensity of the transmission light on the basis of a pulsed light generation signal for generation of pulsed light; first and second optical antennas to emit the transmission light to a space and receive reflected light from a first point and a second point; an optical receiver to perform heterodyne detection on light obtained by mixing received light and local oscillation light; and a signal processor to separate a received signal on the basis of the first and the second frequency components.
1. A laser radar device comprising:
a reference light source to emit laser light;
an optical splitting coupler to split the laser light into transmission light and local oscillation light;
an optical phase modulator to perform phase modulation of the transmission light on a basis of a first linear-phase-modulation signal having a first frequency component and a second linear-phase-modulation signal having a second frequency component in a time section that is different from a time section of the first linear-phase-modulation signal;
an optical intensity modulator to modulate light intensity of the transmission light subjected to the phase modulation in the optical phase modulator, on a basis of a pulsed-light generation signal for generation of pulsed light;
an optical antenna to emit toward a space the transmission light whose light intensity is modulated by the optical intensity modulator, and to receive reflected light generated from the emitted transmission light being reflected at a first point and a second point;
an optical receiver to perform heterodyne detection on light generated by mixing the received light received by the optical antenna and the local oscillation light; and
a signal processor to separate received signal obtained by the heterodyne detection in the optical receiver on a basis of the first frequency component and the second frequency component, and to perform frequency analysis of the reflected light at the first point and the second point.
2. The laser radar device according to claim 1 , wherein the optical phase modulator applies the second linear-phase-modulation signal onto a rising region of the pulsed light to be generated.
3. The laser radar device according to claim 2 , wherein a semiconductor optical amplifier is used as the optical intensity modulator.
4. The laser radar device according to claim 2 , wherein the signal processor includes:
a wind-measurement signal processor to measure information of wind direction and wind speed at the first point on a basis of the received signal corresponding to the first frequency component;
a wind speed detector to detect a wind speed at the first point from the measured information of wind direction and wind speed;
a rotary-member-measurement signal processor to measure rotation information of a rotary member located at the second point on a basis of the received signal corresponding to the second frequency component; and
a rotation speed detector to detect a rotation speed of the rotary member from the measured rotation information.
5. The laser radar device according to claim 1 , wherein:
the optical phase modulator applies the second linear-phase-modulation signal to a trailing edge region of the pulsed light to be generated; and
the signal processor includes an RF switch to suppress leakage light from the laser radar device.
6. The laser radar device according to claim 5 , wherein a semiconductor optical amplifier is used as the optical intensity modulator.
7. The laser radar device according to claim 5 , wherein the signal processor includes:
a wind-measurement signal processor to measure information of wind direction and wind speed at the first point on a basis of the received signal corresponding to the first frequency component;
a wind speed detector to detect a wind speed at the first point from the measured information of wind direction and wind speed;
a rotary-member-measurement signal processor to measure rotation information of a rotary member located at the second point on a basis of the received signal corresponding to the second frequency component; and
a rotation speed detector to detect a rotation speed of the rotary member from the measured rotation information.
8. The laser radar device according to claim 1 , wherein a semiconductor optical amplifier is used as the optical intensity modulator.
9. The laser radar device according to claim 8 , wherein:
the optical antenna includes a first optical antenna and a second optical antenna to emit the transmission light; and
the laser radar device comprises an optical switch to switch an optical path for the transmission light modulated by the optical intensity modulator between the first optical antenna and the second optical antenna.
10. The laser radar device according to claim 8 , wherein:
the reference light source is a wavelength-tunable light source that emits the laser light having two wavelengths;
the optical antenna includes a first optical antenna to emit the transmission light having a first wavelength in the laser light, and a second optical antenna to emit the transmission light having a second wavelength in the laser light; and
the laser radar device comprises a wavelength-separation filter to separate into the transmission light having the first wavelength and the transmission light having the second wavelength for output to the first optical antenna and the optical second antenna, on a basis of wavelengths of the transmission light modulated by the optical intensity modulator.
11. The laser radar device according to claim 8 , wherein the signal processor includes:
a wind-measurement signal processor to measure information of wind direction and wind speed at the first point on a basis of the received signal corresponding to the first frequency component;
a wind speed detector to detect a wind speed at the first point from the measured information of wind direction and wind speed;
a rotary-member-measurement signal processor to measure rotation information of a rotary member located at the second point on a basis of the received signal corresponding to the second frequency component; and
a rotation speed detector to detect a rotation speed of the rotary member from the measured rotation information.
12. The laser radar device according to claim 1 , wherein:
the optical antenna includes a first optical antenna and a second optical antenna to emit the transmission light; and
the laser radar device comprises an optical switch to switch an optical path for the transmission light modulated by the optical intensity modulator between the first optical antenna and the second optical antenna.
13. The laser radar device according to claim 12 , wherein the signal processor includes:
a wind-measurement signal processor to measure information of wind direction and wind speed at the first point on a basis of the received signal corresponding to the first frequency component;
a wind speed detector to detect a wind speed at the first point from the measured information of wind direction and wind speed;
a rotary-member-measurement signal processor to measure rotation information of a rotary member located at the second point on a basis of the received signal corresponding to the second frequency component; and
a rotation speed detector to detect a rotation speed of the rotary member from the measured rotation information.
14. The laser radar device according to claim 1 , wherein:
the reference light source is a wavelength-tunable light source that emits the laser light having two wavelengths;
the optical antenna includes a first optical antenna to emit the transmission light having a first wavelength in the laser light and a second optical antenna to emit the transmission light having a second wavelength in the laser light; and
the laser radar device comprises a wavelength-separation filter to separate into the transmission light having the first wavelength and the transmission light having the second wavelength for output to the first optical antenna and the second optical antenna, on a basis of wavelengths of the transmission light modulated by the optical intensity modulator.
15. The laser radar device according to claim 14 , wherein the signal processor includes:
a wind-measurement signal processor to measure information of wind direction and wind speed at the first point on a basis of the received signal corresponding to the first frequency component;
a wind speed detector to detect a wind speed at the first point from the measured information of wind direction and wind speed;
a rotary-member-measurement signal processor to measure rotation information of a rotary member located at the second point on a basis of the received signal corresponding to the second frequency component; and
a rotation speed detector to detect a rotation speed of the rotary member from the measured rotation information.
16. The laser radar device according to claim 1 , wherein the signal processor includes:
a wind-measurement signal processor to measure information of wind direction and wind speed at the first point on a basis of the received signal corresponding to the first frequency component;
a wind speed detector to detect a wind speed at the first point from the measured information of wind direction and wind speed;
a rotary-member-measurement signal processor to measure rotation information of a rotary member located at the second point on a basis of the received signal corresponding to the second frequency component; and
a rotation speed detector to detect a rotation speed of the rotary member from the measured rotation information.
17. A wind turbine control system comprising:
a wind turbine having blades;
a laser radar device including:
a reference light source to emit laser light;
an optical splitting coupler to split the laser light into transmission light and local oscillation light;
an optical phase modulator to perform phase modulation of the transmission light on a basis of a first linear-phase-modulation signal having a first frequency component and a second linear-phase-modulation signal having a second frequency component in a time section that is different from a time section of the first linear-phase-modulation signal;
an optical intensity modulator to modulate light intensity of the transmission light subjected to the phase modulation in the optical phase modulator, on a basis of a pulsed-light generation signal for generation of pulsed light in which the first frequency component and the second frequency component have pulse widths different from each other;
an optical antenna to emit toward a space the transmission light whose light intensity is modulated by the optical intensity modulator, and to receive reflected light generated from the emitted transmission light being reflected at aerosol in atmosphere and the blades;
an optical receiver to perform heterodyne detection on light generated by mixing the received light received by the optical antenna and the local oscillation light;
a wind-measurement signal processor to measure information of wind direction and wind speed at a long-distance position located farther from the blades, on a basis of the received signal corresponding to the first frequency component;
a wind speed detector to detect a wind speed at the long-distance position from the measured information of wind direction and wind speed;
a rotary-member-measurement signal processor to measure rotation information of the blades on a basis of the received signal corresponding to the second frequency component; and
a rotation speed detector to detect a rotation speed of the blades from the measured rotation information;
a control device to perform control to apply a current for assisting rotation startup of the blades when the blades are not in rotation state and the wind speed is greater than or equal to a threshold value by referring to the wind speed at the long-distance position and the rotation speed of the blades which are detected by the laser radar device; and
a driving device to apply a current for assisting rotation startup of the blades under control of the control device.