使用WRF-Fitch对湖区风电场风力发电机尾流效应特征的数值模拟

为解析不同稳定度情况下多种风机排布配置对尾流效应的强度、作用范围和风能利用效率的影响, 以鄱阳湖地区风电场为例, 使用中尺度数值模式WRF(Weather Research and Forecast)和Fitch尾流模型进行模拟实验。结果表明: 在不同大气层结稳定度情况下, 单个风机尾流效应的影响范围能够达到下游4~10 km处, 对下风向风速的削弱强度可达−0.2~−1.2 m/s。在风的来向上风机数量越多, 下游风速减弱越大; 正方形紧密排布风电场的尾流效应对风速的削弱效果最明显, 而空心菱形稀疏排布风电场的尾流区风速更容易恢复。由于不稳定的大气层结内热力和动力湍流交换强度更强, 更有利于尾流区内中动量的交换和下传, 因此稳定大气层结的尾流效应影响范围比不稳定大气层结更广。风机所在位置垂直剖面上的湍流动能呈现中心最强、向外耗散的特征, QKE(湍流动能的两倍)随着高度增加而先增至最大值(> 19 m²/s²), 再减至0左右, 之后趋于稳定, 最大值出现在约离地90 m的高度, 估计尾流效应的垂直影响范围可达约离地1.1 km的高度。

Case Studies: Simulation on Characteristics of Wind Turbine Wake Effect in a Lake-Side Wind Farm with WRF-Fitch

Meso-scale meteorological numerical model WRF (Weather Research and Forecast) and the Fitch Wake model are adopted to reveal the intension and patch range of TWE (turbine wake effect) in various atmospheric stability, as well as the impact of different turbine configuration on utilization efficiency of wind energy. Case studies are conducted over Poyang Lake region. The results are as followed. Horizontally, the patch range of a single wind turbine's TWE can reach 4 to 10 km downward, with a reduction in wind speed ranging from -0.2 to -1.2 m/s under different atmospheric instability. The reduction in wind speed is more severe with more turbines on the stream track. Among the five cases with different turbine location configuration, the wind speed reducing effect in square case (intensively distributed) is much more apparent than others, while the wind speed in TWE patch tends to recover quickly in hollow diamond case (sparsely distributed). Compared with unstable atmospheric stratification, the TWE under stable atmospheric stratification has a longer patch range,because the turbulent exchange of momentum is intenser in unstable stratification than that in stable stratification. Vertically, the QKE (twice of turbulent kinetic energy) at the wind turbine spot peaks in the core. QKE increases to its maximum value of 19 m2/s2and then decreases to around zero. The maximum QKE appears at the level of about 90 m above ground level, while the vertical impact of TWE can be traced to a height of 1.1 km.