Coordinated control method for flexible direct current transmission system for smoothing new energy output fluctuation

The present invention discloses a coordinated control method for flexible direct current transmission system for smoothing new energy output fluctuation. The method comprises the following steps: an active power of a wind farm and an active power of a photovoltaic power station are collected and an actual value P of a total active power is obtained; a reference value P of the filtered total active power is obtained; the reference value of the filtered total active power is subtracted by the actual value of the total active power of the wind farm and the photovoltaic power station and a corrected capacitor voltage value delta U of a half bridge sub-module is correspondingly obtained according to the absolute value of the difference; the corrected capacitor voltage value ofthe half bridge sub-module is added to an initial capacitor voltage reference value U and the amplitude is limited to obtain a corrected reference value U* of the capacitor voltage; and the number of the half bridge sub-modules needed for eac