Grid-connected inverter and method for filtering AC output thereof

摘要

Disclosed is a grid-connected inverter and a method for filtering AC output thereof. The grid-connected inverter includes an AC output filter which includes two or more switchable filtering modules, with the power capacity of each filtering module corresponding to a different output power of the grid-connected inverter; a monitoring module which is used to perform realtime monitoring on voltage and current outputted by the grid-connected inverter; and a control circuit which is used to calculate an output power grade of the grid-connected inverter according to the voltage and the current monitored by the monitoring module and control switching to the filtering module having a corresponding power capacity according to the power grade, the power grade being selected from a plurality of power grades which are divided according to power capacities of the filtering modules.

主权项

1. A grid-connected inverter comprising:
an AC output filter which includes two or more switchable filtering modules connected in parallel, power capacity of each filtering modules corresponding to a different output power of the grid-connected inverter; a monitoring module which is connected to an AC output end of the grid-connected inverter and is used to perform realtime monitoring on AC voltage and AC current outputted by the grid-connected inverter; and a control circuit which is connected between the monitoring module and the AC output filter, and is used to calculate the output power of the grid-connected inverter according to the voltage and the current monitored by the monitoring module and control, according to a power grade of the calculated output power, switching to the filtering module having the power capacity corresponding to the power grade, the power grade being selected from a plurality of power grades which are divided according to power capacities of the filtering modules; wherein each of the filtering modules includes an LC/LCL AC filter and a first AC contactor which are connected in series, a filter capacitor branch in the LC/LCL AC filter includes a filter capacitor and a second AC contactor which are connected in series, and wherein the control circuit controls switching to the corresponding filtering modules by controlling on-off states of the first AC contactor and the second AC contactor in each of the filtering modules.