Research On 1.55?m All-Fiber Coherent Doppler Laser Radar For Wind Sensing Used In Wind Power Plant

Lidar technology is the frontier of atmospheric wind field detection.In order to simplify the structure of the laser wind radar,reduce the manufacturing cost,improve the signal-to-noise ratio,and achieve fast and accurate measurement of the atmospheric wind field.In this paper,a coherent Doppler laser wind radar for wind farms is studied.The system uses a 1.55?m external cavity laser to provide a narrow linewidth source,and a fiber loop coherent detection optical path,using the same signal and reference light.The path offsets the impact of the environment on the system,replacing the expensive polarization devices such as polarization-maintaining amplifiers and polarization lasers used in conventional radars.The system has simple structure,convenient adjustment,low manufacturing cost and high signal to noise ratio.The main research contents of this paper are as follows:Firstly,the research background and significance of laser wind radar are reviewed,and the latest research progress of wind radar at home and abroad is introduced.The principle scheme is proposed and the overall structure and key components of the wind radar of this project are introduced in detail.Secondly,the atmospheric scattering characteristics that affect the signal strength are analyzed,and the basic characteristics of the echo signal and the noise source are analyzed.The coherent integration method based on quadrature mixing phase discrimination is used to improve the signal to noise ratio of the detection signal.The radar echo signals are simulated and simulated,and the coherent accumulation processing is performed for different times.The simulation results verify that the coherent accumulation can effectively improve the signal-to-noise ratio.On this basis,an all-fiber coherent Doppler laser wind radar system is built.The spherical aberration of the lens affecting the signal in the telescope system is tested.An improved method using aspherical lens to eliminate spherical aberration interference is proposed.The wind speed frequency shift of different sizes and different distance points was actually detected,and the feasibility of the system scheme was verified.Furthermore,the seed light source with different line widths is used for detection.The influence of the line width of the light source on the performance of the system is studied.The linewidth light source of the hundred kHz magnitude is preferred as the key component of the short-range wind radar.Finally,the analog signal is connected to the signal processing system,and the wind speed information is inversed by Doppler frequency shift,and the error does not exceed ±0.5m/s.