A General Decoupled AC/DC Power Flow Algorithm with VSC-MTDC

For a large scale hybrid AC/DC system, it is of great significance to find a power flow algorithm with good convergence and short calculation time. For the purpose, this paper presents a decoupled power flow algorithm for hybrid AC/DC system containing voltage source converter based multi-terminal high voltage direct current (VSC-MTDC) grids. By redefining the boundary of the AC and DC grids at DC side of the VSCs, the power flow calculation (PFC) of the AC grid and the DC grid is decoupled. The VSC station is regarded as one part of the AC grid. Therefore, the power flow of the station is calculated in the AC grid PFC. Additionally, certain adjustments and simplifications are employed to the mismatch equations and Jacobian matrix of DC grids, which is time-saving. For generality, the loss model of the converter and various control strategies of the VSC station are detailedly considered. PFC of a modified New England 10-machine 39-bus test system is executed to show the validity and efficiency of the proposed algorithm.