大地背景下风电机雷达回波信号的仿真与分析

Simulation and Analysis of Radar Echo Signals of Wind Turbine in the Presence of Ground

基于通用的风电机点散射回波模型,建立了考虑倾角的无限大良导体大地模型,并根据多径效应,明确了雷达、风电机及大地之间的4种电磁波传播路径,从而利用镜像原理,推导了大地背景下风电机回波的求解公式。采用短时傅里叶变换的数学方法,获取了大地背景下风电机回波的时频图,结果表明,大地对雷达电磁波的散射作用将会导致风电机回波的组成更为复杂,多普勒闪烁也相应增加,而地面的倾斜还会导致回波的最大多普勒频率发生改变,因此建议风电机回波的后续研究必须考虑大地的影响。

Based on conventional wind turbine point-scattering model, an infinite well-conduc-tive ground model taking angle into account was established. Then, according to the multipath effect, four radar electromagnetic wave propagation paths amony radar, wind turbine and ground were specified and the solving formulas of the radar echoes of wind turbine in the presence of ground were derived by using image theory. The mathematical method of short-time Fourier transform （STFT ） was used to get the time-frequency diagram of echoes. The results show that the scattering effect of ground on radar electromagnetic wave results in more complex composition of echoes, which leads to an increase in the number of Doppler flashings, and the tilt of ground results in the change of the maximum Doppler frequency of echoes. Therefore, it is recommended that the influence of ground must be considered in the study of the echoes of wind turbine.