Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm
Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm
复制标题
大型风电场对日变化大气边界层时空特征的扰动
DOI：
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发表时间：
2017
影响因子：
4.3
通讯作者：
M. Calaf
中科院分区：
文献类型：
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作者：
Varun Sharma;M. Parlange;M. Calaf
探讨了广泛的陆地风电场对昼夜演化的大气边界层时空结构的影响。对嵌入式风电场的真实昼夜循环进行高分辨率大涡模拟。模拟是由恒定的地转速度和来自 CASES-99 现场活动选定时期的时变表面边界条件所强制进行的。通过对作为高度和时间函数的流量的大量统计数据进行分析，结果表明，大范围的风电场使惯性振荡和相关的夜间低空急流垂直向上移动了约 200 m；导致表面和转子盘区域之间的分层强度增强三倍，从而使对流边界层 (CBL) 的形成和生长延迟约 2 小时。这些扰动被证明对大型风电场的潜在功率输出有直接影响，低空射流的位移导致夜间功率输出低于白天。由于 CBL 增长的减少，夜间的低功率状态在早晨过渡后持续了近 2 小时。结果表明，风电场诱导了更深的夹带区域和更大的夹带通量。最后发现风电场的日平均有效粗糙度长度远低于中性条件下理论计算的参考值。
The effect of extensive terrestrial wind farms on the spatio-temporal structure of the diurnally-evolving atmospheric boundary layer is explored. High-resolution large-eddy simulations of a realistic diurnal cycle with an embedded wind farm are performed. Simulations are forced by a constant geostrophic velocity with time-varying surface boundary conditions derived from a selected period of the CASES-99 field campaign. Through analysis of the bulk statistics of the flow as a function of height and time, it is shown that extensive wind farms shift the inertial oscillations and the associated nocturnal low-level jet vertically upwards by approximately 200 m; cause a three times stronger stratification between the surface and the rotor-disk region, and as a consequence, delay the formation and growth of the convective boundary layer (CBL) by approximately 2 h. These perturbations are shown to have a direct impact on the potential power output of an extensive wind farm with the displacement of the low-level jet causing lower power output during the night as compared to the day. The low-power regime at night is shown to persist for almost 2 h beyond the morning transition due to the reduced growth of the CBL. It is shown that the wind farm induces a deeper entrainment region with greater entrainment fluxes. Finally, it is found that the diurnally-averaged effective roughness length for wind farms is much lower than the reference value computed theoretically for neutral conditions.