Photovoltaic inverter system, photovoltaic inverter and resonance damping method and device thereof

The present invention discloses a photovoltaic inverter system, a photovoltaic inverter and a resonance damping method and device thereof. When resonance oscillation occurs at a point of common coupling (PCC) of M photovoltaic inverters in parallel connection, N photovoltaic inverters are selected by an upper computer to switch to a resonance damping function and are enabled to generate comprehensive instruction current according to resonance voltage and resonance current of the PCC and bus voltage thereof, so as to carry out tracking compensation on resonance current of a power grid, thereby realizing suppression of the resonance vibrations; and other M-N photovoltaic inverters are still at a normal grid connection working state, thereby ensuring normal operation of photovoltaic grid connection. The resonance damping method of the photovoltaic inverters requires no extra active power filter (APF) devices, saves cost of photovoltaic power stations, and does not cause resource wastes when the resonance vibrations do not occur, thereby solving the problem of parallel resonance suppression at the cost of cost increase and resource wastes.