风电场并网后将对电力系统运行产生一系列影响。传统半不变量法计算概率潮流(probabilistic power flow,PPF)通常仅考虑风速随机性,可能导致分析结果偏离客观实际。提出一种计及参数模糊性的半不变量法PPF计算方法。针对风速和负荷的随机性及模糊性,建立随机模糊不确定性模型,采用基于增量法的模糊潮流求得状态变量数字特征的可能性分布。同时,计及风速模糊相关性,通过模糊化半不变量法的解析法拟合得到状态变量各阶半不变量三角模糊置信区间。最后,运用Gram-Charlier级数拟合状态量的模糊概率分布。对改进IEEE 14节点系统以及江苏南京78节点等值系统的实际数据进行测试,验证了算法的有效性、准确性及实用性,并具体分析了风速模糊相关性对系统运行特性的影响。
Wind power integration into power grid has a series of impacts on power system. Probabilistic power flow(PPF) based on conventional cumulant method may result in deviation from objective reality when just considering wind speed randomness. Considering fuzzy parameters, a cumulant based PPF method was proposed. A stochastic fuzzy uncertainty model was used to deal with randomness and fuzziness of wind speed and load. Fuzzy power flow based on incremental method was used to obtain membership degree of numerical characteristics of state variables. Meanwhile, considering fuzzy correlation, triangular fuzzy confidence of cumulant was estimated based on fuzzy cumulant method. Finally, Gram-Charlier series was used to estimate fuzzy probability distribution of state variables. Validity, accuracy and efficiency of the algorithm is verified with simulation of modified IEEE14-bus system and Nanjing 78-bus equivalent system. On this basis, impacts of wind speed fuzzy correlation on power system operation characteristics are investigated.