The invention relates to a power coordinated control method for a multi-terminal flexible DC
transmission system. According to the method, a converter
station with larger rated capacity is selected from a VSC-MTDC (
Voltage Source Converter Multi-Terminal DC)
system to serve as a main converter
station, constant
DC voltage control is performed on the main converter
station, the other converter stations are divided into two groups, adaptive droop control and constant
active power control are respectively performed on the two groups of converter stations, the main converter station performs regulation independently when the unbalanced power in the
system is within a regulating range of the main converter station, and when the main converter station is fully loaded or out of operation, the redundant unbalanced power is regulated by a converter station adopting the droop control, the active power outputted by the converter station is automatically regulated according to DC side
voltage changes caused by the unbalanced power so as to enable the
system power to achieve a balance again. The power coordinated control method can avoid a phenomenon of out-of-limit
voltage, reduce
voltage fluctuations at the DC side and make full use of the active
power capacity of the converter station. The method can effectively improve the
control quality of the multi-terminal flexible DC
transmission system, and meet control requirements of the system under different operating conditions.