风资源评估中风切变指数的研究

Research on the Wind Shear Exponent for Wind Resource Assessment

为了对风资源进行准确有效的评估,对风切变指数这一重要参数进行了分析研究。根据风切变指数关系式,给出5种不同的方法分别计算风切变指数;然后根据计算得出的风切变指数与幂律公式推算已知高度的风速,再利用不同计算方法得出的结果与实测风速进行对比分析,选择误差最小的计算方法进行计算,得到较为准确的风切变指数。选用内蒙古乌兰察布市某测风塔共3个测风高度一年内完整的实测数据为例,采用上述方法计算该地区风切变指数。结果表明,由于地面粗糙度和地形等因素的影响,不仅不同地区的风切变指数是不同的,即使是同一地区同一时间段的风切变指数也是不同的;因此,在进行风能资源评估时,应结合风电场的实际情况综合采用这5种方法,选取误差最小的风切变指数。

In order to accurately and effectively assess the wind resource, this paper analyze and studies an important parameter-wind shear exponent. According to wind shear exponential formula, the wind shear exponent is calculated by five different methods; then the known height＇s wind speed is calculated according to the calculated wind shear exponents and power law formula, and the smallest error calculation method is chosen by comparing the cal- culated value and actual value, to obtain more accurate wind shear exponent. With the example of actual wind speed data, within a complete year on three wind measurement height at a mast of Wulanchabu in Inner Mongolia, the wind shear exponent of this area is calculated using the above methods, the results shows that ： due to the im- pact of ground roughness and the topography, not only wind shear exponents are different in different areas, they are also different even in the same area at the same time; wind resource assessment, therefore, should be combined with the actual situation of wind farm, and use these five methods comprehensively to choose the smallest error wind shear exponent.