基于威布尔分布的风功率密度计算方法比较

Comparison of Wind Power Density Calculation Methods Based on Weibull Distribution

[目的]风功率密度是风资源评估重要参数之一,准确地计算风功率密度有赖于风频威布尔分布拟合的准确性,对它进行正确地分析和评估有助于降低投资风险和提高投资决策的可靠性。针对目前风资源评估缺少威布尔分布拟合准确性方面的研究,文章旨通过研究比较那种威布尔分布拟合具有较高的精度,从而提高风资源评估的准确性。[方法]对目前国内外采用的5种威布尔模拟风频分布的方法进行研究,引入决定系数来确定威布尔模拟的准确度,比较威布尔函数计算风功率密度与实测数据计算风功率密度绝对误差和相对误差大小。[结果]结果表明:能量因子法EPF和最大似然法MLE模拟出来的威布尔拟合决定系数高于其他方法,包括经验法(EPJ和EPL)和最小二乘法(LLSA)。用这两种方法所得的参数计算风功率密度,与实测数据计算所得的风功率密度相比较,其绝对误差和相对误差也小于其他3种方法。[结论]研究结果可为风资源评估时选择何种威布尔方法计算风功率密度提供参考依据,客观地反应风电场风资源情况,提高风资源评估的准确性。

[Introduction]Wind power density is an important parameter for wind resource assessment,and the accurate calculation of wind power density relies on the accuracy of fitting the wind frequency with the Weibull distribution.It is helpful that reasonable analysis the wind power density in that decreasing the risks and improving the decision-making of wind farm investment.Considering the lack of research on the accuracy of Weibull distribution fitting in wind resource assessment,the paper aims to improve the accuracy of wind resource assessment by comparing and studying which method provides a higher accuracy in Weibull distribution fitting.[Method]Five commonly used methods for simulating wind frequency distribution based on the Weibull model were studied.The coefficient of determination was introduced to determine the accuracy of Weibull simulation.The absolute error and relative error between the wind power density calculated by the Weibull function and the wind power density calculated from measured data were compared.[Result]The results show that the energy pattern factor(EPF)method and the maximum likelihood estimation(MLE)method obtained higher coefficients of determination for Weibull fitting compared to other methods,including empirical methods(EPJ and EPL)and the least squares(LLSA)method.The wind power density calculate using these two methods,based on the obtained parameters,has smaller absolute errors and relative errors compared to the other three methods when compared to the wind power density calculate from measured data.[Conclusion]The research results can provide a reference for selecting the appropriate Weibull method to calculate wind power density in wind resource assessment and the true features of wind farm can be revealed,then,the accuracy of wind resource assessment can be improved.