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A novel control method, named weighted average current control (WACC), is proposed for damping control of a three-phase grid inverter with an LCL filter. In this method, the sum of partial inverter current and partial grid current is used as the feedback of the current control loop. By using WACC, three-phase current control of the grid inverter can be well decoupled under synchronous rotating frame. Furthermore, the system transfer function is reduced from the third-order system to the first-order system. Consequently, the control loop gain and bandwidth can be increased, which improve the rejection capability to the background grid voltage harmonics. The performance of the proposed control is also analyzed in case of filter inductance variation. Finally, the experiments are presented to validate the theoretical analysis.
Date of Publication: June 2013