Uncertain Power Flow Algorithm for Hybrid AC/DC Grids Incorporating VSCs

The AC/DC hybrid system enhances the ability of the power system to accept renewable energy sources. At the same time, the uncertainty of renewable energy output presents new problems in AC/DC hybrid systems, especially in converter buses. In this paper, affine arithmetic based sequential AC/DC power flow method is established. It can provide less conservative affine estimation results when the system contains uncertain injection power. Furthermore, affine numbers can preserve the correlation between the uncertainties, so the quantitative analysis of the influence of the uncertainty can be carried out by the index of the impact of the uncertain variable on the system state variables. In the affine arithmetic based sequential AC/DC power flow method, the VSC bus is equivalent to the type of the AC bus and the DC bus, and corresponds to the pure AC and pure DC power flow model. The fastness and accuracy of the algorithm are tested by an AC/DC grid incorporating VSCs. At the same time, the impacts of the uncertain variable on the system state variables of the test system is analyzed.