基于不同时间尺度风切变指数推算风资源的对比分析

Comparisons of wind resources based on wind shear indices at various temporal scales

利用2014—2018年辽宁省探空资料分析了水平风速的垂直风廓线分布特征。用2座代表性测风塔逐时梯度风观测分析了采用不同高度组合方案计算出风切变指数的月、日变化特征,分别用月、小时、年风切变指数推算高层风速和风功率密度,并与实测对比。结果表明:沈阳相较于大连地区风速随高度增加较快,180 m高度以上风速基本保持不变,而大连因其纬度低且靠近海洋,300 m以下风速均匀上升。在非复杂地形情况下,距地面10 m高度以上间隔一定高度设立4层风观测,基本可以满足近地层风资源评估需求。受太阳辐射、下垫面、海陆热力性质差异等影响,辽宁省风切变指数日变化特征比月变化更显著。利用小时风切变指数推算高层风速和风功率密度的方案优于采用月、年风切变指数方案。风切变指数日变化越显著,采用逐时风切变指数推算方案越优于其他计算方案。

Using sounding data from 2014 to 2018 in Liaoning province,the vertical wind profile variations in average horizontal wind speed were analyzed.Monthly and diurnal variations in the wind shear index of different height combinations were analyzed based on hourly gradient wind observation of two representative wind measuring towers.Wind speed and wind power at the upper tower were calculated by monthly,hourly,and annual wind shear indexes,respectively,which were then compared with observations.The results show that compared with Dalian,the wind speed in Shenyang increases more significantly with height,and the wind speed above 180 m remains constant,whereas the wind speed below 300 m rises uniformly in Dalian due to its low latitude and proximity to the ocean.Since the terrain is not complex enough,four layers of wind observation are set up at a certain height above 10 m from the ground,which are suitable for surface wind resource assessment.Influenced by solar radiation,underlying surface and thermal property discrepancies between sea and land,the diurnal variations of wind shear index in Liaoning province appear more significant than those of the monthly variations.Hourly wind shear index is superior to monthly and annual wind shear index in calculating wind speed and wind power at the upper tower.The more significant the diurnal variation of the wind shear index is,the better the calculation scheme using the hourly wind shear index appears compared with other calculation schemes.