Converter island starting method for flexible direct-current power transmission system

The invention discloses a converter island starting method for a flexible direct-current power transmission system. The method comprises the following steps: selecting one pole of converter to be charged by a direct-current side; after the charging of the direct current side converter is completed, enabling the island to be unlocked and operate, and establishing an alternating current voltage for the alternating current bus; enabling the other-pole current converter to be connected with an alternating current bus through an alternating current side to charge the current converter in an alternating current manner; after alternating current charging of the converter is completed, enabling the converter to be unlocked in a constant direct current voltage control mode; and after the constant direct current voltage control mode is unlocked stably, merging into a direct current network, and switching to an island control mode to finish island starting. The method aims at a flexible direct-current power transmission