The power curve performance of wind turbines located on the northeast coast of Brazil was investigated. The coastal site has wind characteristics typical of the offshore environment, where both turbulence intensity (TI) and wind shear are consistently low. The wind farm has 20 turbines with 0.9 MW of rated power, hub height and rotor diameter of 55 and 44 m, respectively. The experiment was carried out from August 2013 to July 2014 and included a 100-m met-mast, with five instrumented levels including two 3D sonic anemometers, and a lidar wind profiler. Both were installed upstream of the wind turbines in the prevailing wind direction. Three turbines near the met-mast were used to determine the average power curve for this site by separating the SCADA dataset according to the quartiles of TI and wind shear. The TI was calculated at 60 m and the wind shear between 40 and 98 m. In addition, at 100 m, the 3D sonic anemometer measured wind speed and sonic temperature with an acquisition rate of 20 Hz, to compute atmospheric stability using the eddy covariance method. The results show that TI is the parameter that has the most significant effect on the power curve performance. At high TI (> 7.5), the measured power coefficient (CP) curve was similar to that provided by the manufacturer, whereas for low TI (< 5.4) the CP curve showed a poorer performance relative to that of the manufacturer's. Since the winds blow consistently from the ocean, very stable and very unstable conditions are less frequent, and thus the typically unstable, nearly unstable and neutral conditions produce winds with low TI and wind shear. This stationary condition of low TI causes the measured power curve to show systematically poorer performance than the manufacturer's power curve, which leads to an annual energy production difference of - 2.0. In the worst scenario for a consistently low TI (< 5.4), the difference may reach up to - 5.6. Thus, the typical low TI of the offshore environment could negatively impact the energy production of wind turbines.
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机译：研究了位于巴西东北海岸的风力发电机组的功率曲线性能。沿海地区具有近海环境典型的风特征，湍流强度（TI）和风切变始终较低。该风电场拥有 20 台涡轮机，额定功率为 0.9 MW，轮毂高度和转子直径分别为 55 米和 44 米。该实验于2013年8月至2014年7月进行，包括一个100米长的气象桅杆，有五个仪器水平仪，包括两个3D声波风速计和一个激光雷达风剖面仪。两者都安装在风力涡轮机的上游，在盛行风向上。根据TI和风切变的四分位数分离SCADA数据集，使用靠近气象桅杆的三台涡轮机来确定该站点的平均功率曲线。TI的计算值为60 m，风切变在40至98 m之间。此外，在100 m处，三维声波风速计以20 Hz的采集速率测量风速和声波温度，使用涡度协方差法计算大气稳定性。结果表明，TI是对功率曲线性能影响最显著的参数。在高TI（>7.5%）下，测得的功率系数（CP）曲线与制造商提供的曲线相似，而对于低TI（<5.4%），CP曲线的性能相对于制造商的性能较差。由于风一直从海洋吹来，因此非常稳定和非常不稳定的条件不太频繁，因此通常不稳定、几乎不稳定和中性的条件会产生具有低 TI 和风切变的风。这种低 TI 的稳态条件导致测得的功率曲线显示出比制造商的功率曲线更差的性能，这导致年发电量差异为 -2.0%。在TI持续偏低（<5.4%）的最坏情况下，差异可能高达-5.6%。因此，海上环境典型的低TI可能会对风力涡轮机的能源生产产生负面影响。
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