Unbalanced power flow algorithm for AC&DC hybrid distribution network with diverse-controlled VSC-MTDC converts

摘要

The paper aims to propose an algorithm to calculate the power flow of an AC&DC hybrid distribution system. AC&DC distribution networks have recently attracted increasing attention, for the distributed generations (DGs) and DC loads can be integrated in DC networks in more simple and flexible ways than AC networks. Many efforts have been made to deal with the power flow problem of hybrid networks, however, the DC-side power flow's effect on three-phase unbalanced AC side and the influence to entire distribution system which DG directly connected in the DC side are both not considered. Therefore, this paper discusses the grid architecture with multiple AC&DC feeders. Then, models of VSC-MTDC, DC/DC converters, DGs, and other elements are formulated for power flow calculation. Furthermore, power flow equations of DC distribution and VSC converters are deduced in detail. As for converters under different control strategies and diverse forms of linking combinations between AC&DC grids, calculating approaches are considered to be of partial differences. Considering these distinct cases, a specific and improved sequential method is employed to compute distribution network's power flow. Simulation results on a modified IEEE 13 Node Test Feeder demonstrate the rapidity, accuracy, and easy-convergence of the algorithm.