Power grid frequency-modulating method based on flexible direct-current transmission system

The invention aims to need a power grid frequency-modulating method based on a flexible direct-current transmission system. On the basis of a synchronous motor simulation control strategy of a convertor station, the power grid frequency-modulating method based on the flexible direct-current transmission system comprises the following steps: (1), obtaining an instruction value omega* of output alternating voltage angular frequency of the convertor station; (2), obtaining an instruction value theta of a phase angle of alternating voltage; (3), setting an instruction value of output active power P* of the convertor station; (4), enabling an active power set value to be equal to an active power practical value; and (5), inhibiting transmission of large disturbance between interconnected power grids, and limiting the amplitude of the active power set value. Compared with the prior art, only the variable of the local convertor station is necessary to use; the variable of the opposite convertor station is unnecessar