1.State Key Laboratory of Power Transmission Equipment & System Security and New Technology (Chongqing University), Chongqing 400044, China;2.Grid Planning and Research Center of Guangdong Power Grid Co., Ltd., Guangzhou 510699, China;3.China Electric Power Research Institute, Beijing 100192, China

With the development of power systems, probabilistic power flow analysis of interconnected power grids is necessary to take into account the influence of uncertain factors such as renewable energy generation and load fluctuations, and the continuous expansion of power grids will significantly increase the corresponding computation burden. Therefore, in order to improve the calculation efficiency of the probability power flow for interconnected power grids, a probabilistic power flow calculation method for interconnected power grid is proposed based on external network static equivalent method and unscented transformation method. Firstly, the unscented transformation method is used to generate the set of sample points for the probabilistic modeling of equivalent parameters at the boundary, and the external network static equivalent method based on multiple operation points is proposed, that is, each sample point obtains equivalent parameters based on the results of its improved DC power flow calculation, to establish the probability model of the input random variables of the internal network after equivalence. Then, a new set of sample points is generated by the unscented transformation method through the probability model, so as to calculate the probabilistic power flow of the internal network after equivalence. Finally, the accuracy and speed advantages of the proposed method are demonstrated on multiple test systems. The proposed method reduces the dimension of input random variables and the system size in probabilistic power flow calculation with the help of the probability equivalent technology, thus reducing the number of deterministic power flow calculations and the single calculation time required for its analysis, and realizing the double dimension reduction in the calculation of this application.