The invention discloses a self-adaptive quasi-PR active damping low-frequency
harmonic suppression method, and the method comprises the steps: introducing a self-adaptive quasi-PR control link on the basis of conventional double-closed-
loop control, introducing a
phase compensation structure on the basis of quasi-PR control, and adding a
voltage proportion feedforward link at a PCC grid-connected point, thereby obtaining the self-adaptive quasi-PR active damping low-frequency
harmonic suppression method. According to the method, zero-static-error tracking of grid-connected current to sine given current is achieved, the content of third, fifth and seventh
harmonics in the grid-connected current is reduced, active damping of the
system is increased, the capacity of the
system for resisting
power grid voltage disturbance is improved, meanwhile, main low-frequency
resonance existing in an
inverter in the grid-connected cluster
system is equivalently converted and offset, and therefore the grid-connected cluster system is optimized.
Self resonance and
parallel resonance of the LCL photovoltaic grid-connected
inverter are effectively inhibited; multi-point low-frequency
resonance suppression of the multi-
inverter grid-connected system is achieved, passive damping control can be replaced, the hardware cost and
power consumption are effectively reduced, and the stability of the grid-connected system is remarkably improved.