Closed loop selective harmonic elimination applied to a grid connected PWM converter with LCL filter

This paper presents the development and design of a control strategy applied to a three-phase grid connected PWM converter with Selective Harmonic Elimination (SHE). First, the transcendental equations of SHE are solved offline and then stored in a look-up table inside of the SHE-Modulator, which is implemented using a FPGA. Synchronism with the grid is obtained using a modified Digital PLL which includes the Modulator with SHE. A discrete model is obtained in dq synchronous frame for the converter with LCL-filter with passive damping and dq PI controllers are used to provide zero steady-state error of grid current. Finally, simulation results are presented to validate the proposed approach.