Backup power supply system of offshore wind generating set

The utility model discloses a back-up power supply system of an offshore wind generating set, which comprises a diesel generator used as a back-up power supply of the wind generating set and used for supplying power to the wind generating set under the condition that a power grid loses power; the diesel generator controller is used for executing start-stop control of the diesel generator and remote signaling and remote control of state information of the diesel generator; the dual-power switch is used for switching a power supply mode of a power supply and is provided with two gears, namely a power grid power supply gear and a diesel generator power supply gear; wherein the diesel generator is connected with the dual-power switch, the dual-power switch is connected with a power grid through the auxiliary transformer, the dual-power switch is connected with an auxiliary power system of the wind generating set, the auxiliary power system is connected with a main controller of the wind generating set, and the ma