The invention discloses a direct-driven fan
system impedance modeling method considering
frequency coupling, and the method comprises the steps: S1, obtaining a mathematical expression of a blade
tip speed ratio and output power according to a wind
turbine airflow model of a direct-driven fan; s2, according to
equivalent circuit topology modeling under a dq coordinate
system of the
permanent magnet synchronous motor, obtaining an expression of
electromagnetic torque and
electromagnetic power; s3, according to the control structures of the
machine-side converter and the grid-side converter of the direct-drive fan, modeling is carried out respectively, and an equivalent
admittance mathematical expression of the
machine-side converter and six disturbance
admittance expressions in the direct-drive fan are obtained; and S4, based on the mathematical expressions of the output power, the
electromagnetic power, the equivalent
admittance and the disturbance admittance obtained in S1, S2 and S3, establishing the equivalent admittance / impedance of the direct-drive fan
system. According to the method, multi-time-
scale control and full-working-condition
frequency domain port characteristics of the direct-driven fan system can be effectively represented, and the equivalent impedance model can accurately analyze the stability of the system.