The work principle and control mode of the multi-terminal DC system with voltage source converter(VSC-MTDC)are essentially different from the conventional DC system. The current static security analysis cannot directly analyze and calculate the AC/DC system with VSC-MTDC. Firstly

a calculation framework for AC/DC static security analysis of VSC-MTDC/AC hybrid system is proposed based on the traditional static security analysis of AC system

the adopted functional realization method and key technologies are described. Then

in the calculation of expected faults

the change of operation conditions of AC and DC power grids is taken into account to ensure that the calculation results are consistent with the actual operation conditions of power grids

which improves the accuracy of static security analysis and calculation. Finally

hybrid AC/DC system with four-terminal flexible DC system is established to verify the efficiency and practicability of the proposed method.