A Solar Series Grid Following Harmonic Compensator with Enhanced Grid Current Shaping and Active Power Injection Capability

This work proposes a solar-based series inverter configuration to demonstrate the superior power quality shaping with the active power injection capability in grid-interfaced nonlinear load applications. The proposed configuration realizes the AC network in series. It ensures the reduced AC filter size and DC voltage compared to the conventional inverter topologies. The series inverter configuration mimics the double switching frequency across the load, making the system's overall bandwidth higher than the conventional inverter. The improved bandwidth ensures reduced attenuation towards lower-order load-demanded harmonics. In addition, as the filter size plays a role in harmonic processing capability, in this work, an optimum filter size is derived by analyzing the nonlinear load current rise time signatures at different load resistances and filter inductances. With the appropriate filter sizing, the dynamic solar power and harmonic injection are accomplished by developing a dedicated closed-loop control mechanism for series inverters. The developed control methodology instantaneously derives combined references to individual inverters through instantaneous AC load harmonic segregation and DC solar power computation. With the derived control mechanism, the superiority of the proposed series inverter over a parallel isolated inverter in terms of enhanced harmonic compensation and dynamic solar power injection is demonstrated through experimental results.