The invention discloses a global cooperative control method and
system for unbalanced fault ride-through of a multi-terminal DC
power grid, and the method comprises the steps: constructing a fault detection model based on the positive sequence
voltage drop depth and the negative sequence
voltage size of the AC side of each converter
station, automatically judging an unbalanced fault, and carrying out the fault detection when the fault is detected. Calculating the maximum allowable active current based on a fault
station unbalanced current control model to carry out
current limiting control on the converter
station; and carrying out output power adjustment on the
DC voltage deviation of the non-fault station based on the non-fault station power
cooperation model. Asymmetric fault ride-through is carried out by using a constrained and optimized current instruction generation
algorithm, and the capacity of a converter is dynamically and accurately distributed and utilized in a limited manner, so that the
voltage support capability of a fault alternating-current
power grid is maximized, and globally optimized adaptive power distribution is realized; the power of the non-fault station is calculated and distributed in a centralized manner and is dynamically adjusted according to the real-time available capacity, so that the self-adaption and
global optimization of the running state change of the
power grid are realized, and the
fault handling toughness and reliability of the power grid are improved.