Method and system for identifying negative weak damping unit of power system

The invention discloses a negative weak damping unit identification method and system for a power system, and the method comprises the steps: collecting abnormal data of a unit in the power system, carrying out the preprocessing, obtaining an oscillation signal of each generator, carrying out the mode decomposition, obtaining a discrete time sequence parameter of each oscillation signal, and carrying out the recognition of the unit; according to the method, a damping torque analysis method is utilized to obtain a damping torque coefficient of each generator in each oscillation mode according to discrete time sequence parameters of each oscillation signal, and the negative and weak damping unit of the power system is identified in combination with the damping torque coefficients. Under the condition of low-frequency oscillation or ultralow-frequency oscillation, a unit causing oscillation is found by identifying negative damping or weak damping in a power system, so that an ultralow-frequency oscillation strat