Method and system for analyzing subsynchronous oscillation of grid-connected inverter based on open-loop transfer function

The invention discloses a grid-connected inverter subsynchronous oscillation analysis method and system based on open-loop transfer function, and belongs to the technical field of grid-connected inverter control, and the method comprises the steps: carrying out the small signal linearization of a voltage and current conversion process of an inverter grid-connected system; combining a small signal control equation of the phase-locked loop to obtain a phase-locked loop transfer function; deriving a transfer function of inductance and capacitance of the controlled object; in combination with the inverter control link transfer function, a small signal model of the grid-connected inverter connected to the alternating current power grid is obtained, and a direct current voltage control loop open-loop transfer function is obtained; and analyzing the subsynchronous oscillation risk when the grid-connected inverter accesses the weak AC power grid. On the basis of a linearization analysis method, the whole small signal