The invention relates to the technical field of direct-current micro-grids, in particular to a direct-current micro-grid large-
signal stability judgment method and
system, and the method comprises the steps: firstly carrying out the simplification and equivalence of a direct-current micro-grid, and obtaining a simplified equivalent diagram of the direct-current micro-grid, and a correlation expression of the simplified equivalent diagram; secondly, constructing an equivalent
mathematical model of the direct-current micro-
grid system according to a simplified equivalent diagram correlation expression; then, according to the equivalent
mathematical model of the DC micro-
grid system, constructing a state equation of the DC micro-
grid system; then a Lyapunov direct method is utilized to limit a state equation, and a stability constraint condition for judging the stability of the large
signal of the direct-current micro-grid is deduced; and finally, according to a stability constraint condition,
constant power load limit values are set in a classified manner, a judgment process is designed, and the large
signal stability of the direct-current micro-grid is judged according to the
constant power load limit values. The problem that the large-signal stability of the single direct-current micro-grid with the comprehensive load cannot be simply and quickly judged is solved.