The power flow calculation of large power grid containing voltage source converter based(VSC-based)high voltage direct current(HVDC)is the foundation for in-depth study of the operation characteristics. Power flow calculation can be divided into two types which are alternative algorithm and simultaneous algorithm. The simultaneous algorithm cannot reuse existing AC power flow calculation while the alternative algorithm has such drawbacks as weak convergence and inherent error. Based on interface correction equation technology

this paper devises a decoupled power flow algorithm with VSC-based HVDC. The nodes of AC and DC side of converter are split and the whole system is divided into the converter

AC network and DC network. With the help of interface modification equation

AC grid and VSC-based HVDC power flow calculations are able to proceed separately. This algorithm has the advantages of high extensibility and good convergence. The validity and superiority of the algorithm is verified by actual power system data with VSC-based HVDC.