考虑光伏出力相关性的配电网概率潮流

分布式光伏发电出力随机性强,且同一区域内的光伏出力相关性显著。考虑光伏接入的配电网概率潮流研究,关键在于相关非正态的光伏输入随机变量的处理。采用Nataf变换进行相关非正态输入随机变量的抽样,并与点估计方法相结合,提出了考虑光伏出力相关性的配电网概率潮流计算方法。与传统处理相关问题的正交变换相比,Nataf变换能够反映相关系数在不同变量空间中的变化,因此,在处理相关非正态随机变量方面,Nataf变换比正交变换法更为精确。通过对含有分布式光伏发电的IEEE 33节点算例系统的计算,验证了Nataf变换的优越性。进一步,分析了不同光照强度相关系数、负荷功率波动大小以及估计点个数对概率潮流计算结果精度的灵敏度。

Probabilistic Load Flow of Distribution Network Considering Correlated Photovoltaic Power Output

The power outputs of photovoltaic generators (PVs) are strongly random, and appreciably correlated in close proximity. The research on probabilistic load flow of distribution network mainly focuses on how to deal with correlated random variables. Nataf transformation is used to sample correlated non-normal random variables and the method of combining Nataf transformation with the point estimate method (PEM) is proposed to develop a new correlated probabilistic load flow method. Compared with the orthogonal transformation, Nataf transformation is able to reflect the changes of correlation coefficients in different sampling spaces, and therefore it is more accurate. The method is applied in a modified IEEE 33-bus test system with PVs integration for calculation of average relative errors in bus voltages. Compared with orthogonal transformation, the advantage of Nataf transformation is verified. Furthermore, a sensitivity analysis is made on three factors, the correlation coefficients of solar radiation, the load power fluctuation and different estimating points. This work is supported by National Basic Research Program of China (973 Program) (No. 2013CB228203).