Multi-terminal VSC-HVDC grid-connected transmission system controlling method applied to wind power plant

The invention discloses a multi-terminal VSC-HVDC grid-connected transmission system controlling method applied to a large wind power plant. Wind power plant side convertor station outer ring power conducts inner ring current PI control, a grid field side convertor station outer ring direct voltage conducts inner ring current feedback linearization decoupling control, and therefore response characteristics and dynamic performance of a controller are improved. When operation of the wind power plant fluctuates greatly and a system loses capacity for adjusting the direct voltage, multi-terminal direct voltage control of direct voltage deviation is led into other convertor stations of the wind power plant for replacing a grid side convertor station to execute a voltage regulating task, therefore, power balance is maintained, normal operation of the system is ensured, and the effect that the system operates stably at a new operating point is also ensured.