Compensation of current harmonics caused by local nonlinear load for grid-connected converter

This paper proposes a controller design to compensate the current harmonics from the nonlinear load when a grid-connected inverter operates as an active power filter. When the LCL filter is installed at the output of inverter, the controller should be designed differently depending on the location of the nonlinear load. As this nonlinear load is connected to the grid before or after the grid side inductor of LCL filter, the current feedback to be compensated is different as the location of the nonlinear load. Therefore, it is necessary to design the controller depending on the location of the nonlinear load. The PR based controllers to compensate harmonics caused by local nonlinear load have been proposed and analyzed as the structure of the controller. The proposed algorithm has been verified through the PSiM simulation results.