计及风电场有功无功相关性的随机潮流计算

Probabilistic Load Flow Calculation of Power System Integrated with Wind Farms Considering PQ Relativity

在随机潮流计算中,一般认为各已知随机变量是相互独立或是线性相关的,采用这种假设后可以方便的使用随机潮流法在已知系统随机变量分布下计算系统状态变量与支路潮流等分布信息。然而,目前我国风电机组多为异步电机,其有功无功非独立变量,也不存在线性关系,因此针对这个问题本文在文献的基础上提出考虑风电场有功无功非线性相关的随机潮流计算法。该方法将风电场有功无功同它们在灵敏度矩阵中对应的权重元素组合成一个独立随机变量。在考虑风电场出力随机波动、负荷变化以及发电机停运等随机因素下用半不变量法进行随机潮流计算,得到电力系统各节点电压的概率分布。以含风电场的IEEE-14节点系统作算例分析,并以蒙特卡洛法作为标准,计及风电场有功无功非线性相关的随机潮流法比一般的随机潮流法更准确。

It is generally acknowledged that in the probabilistic load flow （PLF） calculation,all known random variables are mutually independent or in a linear correlation. Based on such assumptions,PLF methods can be conveniencently used to calculate the distribution informations such as system state variables and branch flows under the distribution of system random variables. However currently,most of the Chinese wind generators are asynchronous ones,who＇s active or reactive power is not an independent variable nor in a linear relationship. Here,this paper proposes a PLF method considering PQ relativities of wind farms base of the literature,which combines PQ relativities of wind farms with corresponding weighting values of sensitivity matrix and converts them to an inde-pendent random variable. Cumulative PLF -R calculation could yield voltage probabilistic distributions of power system with wind farms integrated on the basis of full consideration about randomicity of wind speed and other stochastic disturbances,such as varying loads and generation unit. An IEEE-14 system integrated with wind farms is been analyzed. It shows that PLF-R method which PQ relativities are taken into account is much more accurate than normally PLF methods employing Monte Carlo method as the standard.