风速风向联合概率密度分布的一种经验函数模型

对风速与风向边缘分布采用统一的极值概型描述,提出了一种可适用于多峰极值以及总体样本的风速风向联合概率分布函数的经验解析表达式。模型包括7个参数,可由实测数据利用非线性最小二乘方法拟合得到。对模型参数拟合时的初值选取方法提出了建议,并对典型的风向双峰值情况,给出了峰向区间的划分方法;利用双峰总体、双峰极值以及单峰极值3种不同类型的实测数据,检验了模型的适用性。结果表明,该模型可以较好地描述不同类型总体样本或极值样本的风速风向联合概率密度特性,可供风向设计风速的确定、风速评估及场地风能评估等工程问题参考。

An Empirical Joint Probability Density Function of Wind Speed and Direction

Field measurement of wind turbulent properties is a long-term and fundamental task for structural wind engineering since uncertainties of wind load is actually the key factor that affects the analysis accuracy of wind-resistant structures. Among many turbulent wind parameters as wind spectrum, wind profile, turbulent intensity and so on, the joint probability density function of mean wind speed and direction is an important but less addressed property. This paper pres- ents an empirical joint probability density function （JPDF） of mean wind speed and direction. The proposed JPDF model is actually built from marginal distributions of wind speed and wind di- rection which are assumed as an Extreme-Value distribution. The model has seven unknown co- efficients that can be obtained by fitting the model to the field measured data. Details of the JPDF model are first discussed with focus on modeling procedure for both unimodal and bimodal scenar- io and approaches for determining the modal parameters. The applicability and feasibility of the model is then validated by three different types of field measurements, which are unimodal and bimodal wind data from parent population and bimodal wind sample form extreme value data. It is concluded from the results that the proposed JPDF model can represent quite well the joint dis- tribution properties of wind speed and direction from different data source, and it can be further adopted for determining the directional design wind speed and assessment of wind energy.