相干多普勒激光雷达风场反演方法研究与实验印证

Research on Wind Retrieval Method of Coherent Doppler Lidar and Experimental Verification

提出基于共轭梯度算法的速度方位显示(VAD)风场反演方法,应用最优化理论,将共轭梯度算法代替传统VAD方法中的傅里叶级数展开来求取最优解,并针对算法在风场反演应用时存在不收敛于最优解的问题,使用Hessian矩阵对算法进行了修正。同时开展了多普勒激光雷达与符合IEC 61400-12-1国际标准的高精度风杯风速计的43天对比实验,结果显示,当激光雷达的方位角扫描范围为60°、径向个数为7个时,两者的风速、风向相关系数分别为0.991和0.998,风速、风向标准偏差分别为0.52m/s和5.1°,风速、风向偏差分别为-0.02m/s和3.6°。对比实验结果表明,基于共轭梯度算法的VAD风场反演方法使用较小的扫描方位角仍能保证其测量的准确性满足国际标准,具有更强的适用性,同时印证了激光雷达系统的测量性能,为动态复杂风场的监测提供了更佳的选择。

A velocity azimuth display（VAD）wind retrieval method based on conjugate gradient algorithm is proposed,in which the conjugate gradient algorithm is used to replace the solution of Fourier series expansion in original VAD method by using optimization theory.In order to solve the problem that the algorithm does not converge to the optimal solution in wind retrieval,the Hessian matrix is used to modify the algorithm.At the same time,a synchronous comparison experiment had been carried out with Doppler lidar and standard wind cup anemometer in accord with IEC 61400-12-1 international standards for 43 days.The results show that,when the azimuth scanning range and radial number of lidar are 60°and 7 respectively,the correlation coefficients of wind speed and wind direction are 0.991 and 0.998,the standard deviations of wind speed and wind direction are0.52 m/s and 5.1°,the deviations of wind speed and wind direction are-0.02 m/s and 3.6°.The results of comparison experiment prove that the VAD wind retrieval method based on conjugate gradient algorithm can guarantee the measurement accuracy to meet international standard in case of low azimuth scanning range with strong applicability.Meanwhile,the measurement performance of lidar system is confirmed,which provides a better choice for the monitoring of dynamic complex wind field.