(1. State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University), Beijing 102206, China; 2. China Electric Power Research Institute, Beijing 100192, China)

The development of intermittent energy significantly enhances the operation uncertainty of power systems,posing new challenges to power system operation and control. Based on the uncertainty quantification (UQ) theory, this paper proposes a stochastic collocation probabilistic load flow (PLF) algorithm, which utilizes the generalised polynomial chaos (gPC). By constructing affordable deterministic nonlinear equations, the solutions, or quantities of interest, are expressed as convergent series of gPC expansions in terms of random inputs, with their distribution functions solved by calculating the spectral coefficients of gPC expansions. This algorithm is capable of solving the contradiction between accuracy and computational complexity. The effectiveness, practicality and accuracy of the proposed algorithm is proved by the simulation of IEEE14-bus and IEEE118-bus systems, which shows that it has good engineering application prospects in PLF analysis for renewable energy connected power systems. This work is supported by National Basic Research Program of China (973 Program) (No. 2012CB215203) and National Natural Science Foundation of China (No. 50907034).