In recent years, grid connected renewable systems are increasingly becoming part of the distributed power generation. Most distributed generation systems require a two-stage power processing – the first stage does the maximum power tracking and the second stage for grid interfacing. A power topology based on high frequency switched DC-DC converter followed by three-phase inverter for providing isolated ac power was presented in the previous seminar talk. A suitable power filter is necessary for grid interfacing since the harmonics cannot be allowed to go into the grid. An LCL filter is used due to smaller magnetic components sizes as compared to L filter for similar harmonic attenuation. The design of LCL filter based on a cost-per-joule minimization is presented in this seminar talk. The impact of the lower filter components on inverter device selection and total cost is also discussed.

The talk also presents a suitable control algorithm for utilizing selective harmonic elimination PWM pattern, grid synchronization, active and reactive power injection. The control system is designed to achieve an explicit control of voltage magnitude and phase angle (with respect to grid voltage) as a means of reactive and active power injection respectively, independently. Finally, the proposed control system is validated through both simulation and experimentally. The experimental results shown for different cases are observed to verify the method proposed and the simulation studies.