| With the large-scale construction of mountain wind farms,the problem of multiscale interaction between mountain wind turbines,incoming currents and complex terrain has become prominent.Therefore,to analyze the characteristics of atmospheric boundary layer and its influence on wind turbine performance in mountain terrain in Yunnan-Kweichow Plateau,considering the development trend of wind power construction in China and some problems encountered in wind energy development in complex terrains,using the method of field experiment with advanced measurement tools combined with SCADA system of wind turbines,were studied on the atmospheric boundary layer and large horizontal axis wind turbine at a mountain wind farm in Yunnan-Kweichow Plateau in Spring,The main details of the study are shown below:First,the applicability of the ground-based Li DAR Molas B300 in mountainous areas was verified.In this paper,the measurement accuracy of Molas B300 is verified in terms of the signal-to-noise ratio of radar measurement data,reliability,and comparison of radar data at different locations.The results indicate that the mountainous atmospheric boundary layer data collected based on Molas B300 are valid and reliable.Second,based on the data collected by Molas B300,the characteristics of the spatial and temporal distribution of the characteristic parameters of the atmospheric boundary layer were investigated.The parameters used to describe the atmospheric boundary layer characteristics in this paper are temperature,wind direction,wind speed,turbulence intensity,turbulent kinetic energy,turbulent dissipation rate and atmospheric stability.The study shows that in mountainous terrain,there are large differences in the atmospheric boundary layer characteristics at different locations.1.4 ℃ difference in the average daily temperature difference between 8# and 9# radar measurement locations;12.17° difference in the average wind direction;the Weibull parameters are c=10.8645 and k=2.1758 for 8# and c=15.8599 and k=2.4479 for 9#;the average turbulence intensity is 0.23 for 8# and 0.15 for 9#;the average turbulence energy is45.37% higher for 8# than 9#,and the turbulence dissipation rate is much higher for 8#than 9#;the largest percentage of A class atmospheric stability is 31.99% for 8# and21.43% for neutral condition D class,and the highest percentage of neutral condition D class is 36.14% for 9#.Third,based on the ground-based Li DAR Molas B300 and SCADA system,the influence of typical parameters of mountainous atmospheric boundary layer on wind turbine performance was analyzed.To begin with,the representativeness of the wind turbine equivalent parameters and hub center height parameters were evaluated.The results show that the distributions of wind speed and turbulent dissipation rate at hub center height are still representative in mountainous terrain,while the distributions of turbulent intensity and turbulent kinetic energy at hub center height are less representative.Next,the effects of typical parameters of the mountain atmospheric boundary layer on wind turbine performance were analyzed.The results suggest that there is a drop in the power curve of the mountain wind turbine,and the full wind speed is about 2.5 m/s higher than the rated wind speed of the turbine.Below the wind speed of 6 m/s,the output and speed of the unit decreased under the low turbulence intensity condition;under the low wind shear condition,the power output and speed of the unit decreased;the same pattern as that under the low turbulence intensity and low wind shear condition is also shown under the class D atmospheric stability condition.At the same time,the output of the unit under high turbulence intensity and high wind shear conditions has strong fluctuation,while only the power decreases under class A atmospheric conditions.In addition,the effects of three typical parameters on the wind turbine torque were analyzed.The results demonstrate that low turbulence intensity,low wind shear and stable atmospheric conditions all increase the wind turbine torque.This study helps to improve the power generation efficiency and reduce the unit load of wind turbines in mountainous areas with important impact.At the same time,it provides a reference for macro and micro site selection in the construction of mountain wind farms,as well as revealing the change pattern of atmospheric boundary layer in mountainous areas. |
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