典型风电场地形大气稳定度对风机出力的影响

Influence of Atmospheric Stability on Wind Power Output Under Typical Wind Field Topography

[目的]分析了大气稳定度对风机出力的影响,为提高计算流体动力学(Computational Fluid Dynamics,CFD)风能资源模拟精度提供技术参考。[方法]选取立于平坦和复杂山地两类典型地形上的两座测风塔不同高度的风速、气温、气压等观测数据,使用莫宁-奥布霍夫长度法分别计算两座测风塔所在区域的大气稳定度,参照Irwin大气稳定分类标准对稳定度计算结果分类,再根据分类结果进行两座测风塔轮毂高度处出力分析。[结果]结果表明:在近地面层,复杂山地大气热效应造成的表层垂直混合作用更为明显,造成的大气不稳定性较为强烈,但垂直混合作用不充分;复杂山地大气稳定度对风机出力的影响大于平坦地形,其不确定性更强。[结论]在进行CFD风电场流体建模时需要考虑大气稳定度的影响,特别是超低风速复杂山地场址条件下,大气稳定度的评估对风机选型及发电量仿真精度尤为重要。

[Introduction] In order to analyze the influence of atmospheric stability on the output of wind turbines,and to provide technical reference for improving the simulation accuracy of CFD wind energy resources.[Method] Based on the observation data of different heights of two wind towers in flat and complex mountainous terrain,including wind speed,air temperature,air pressure and other data of multi-layer height,the atmospheric stability of the two wind towers in the region was calculated by using the MoningObkhov length method,and the stability calculation results were classified according to Irwin atmospheric stability classification standard.[Result] The results show that:in the near surface layer,the vertical mixing effect caused by the atmospheric thermal effect in complex mountain area is more obvious,and the atmospheric instability is stronger,but the vertical mixing effect is not sufficient;The impact of atmospheric stability on wind turbine output in complex mountainous area is greater than that in flat terrain,and its uncertainty is higher.The reason largely depends on the complexity of atmospheric stability,so it is more necessary to consider the impact of atmospheric stability in wind energy resource assessment.[Conclusion] It is necessary to consider the influence of atmospheric stability in CFD wind farm fluid modeling,especially under the condition of ultra-low wind speed complex mountain site,the evaluation of atmospheric stability is particularly important for fan selection and power generation simulation accuracy.