A Study on Power Quality Improvement by Active Power Filter in Hybrid Sustainable Energy Systems

In this paper, power quality issues due to the grid integration of a dispersed generation system containing multiple power generators are studied. A centralized DC bus architecture is considered for the proposed hybrid sustainable energy system (HSES), where the power from DC bus is conditioned by the grid-connected inverter to supply the linear and nonlinear loads connected at the point of common coupling (PCC). However, the presence of multiple power electronic converters and nonlinear loads possesses an alleviated threat of harmonic pollution at the PCC. Moreover, the conventional LC-based passive filter connected after the inverter is ineffective in mitigating the harmonics generated for such a system. Hence, an effort is made to design and control an active power filter (APF). The designed APF is integrated with the HSES at the PCC. Results of various case studies prove that proper design, control, and integration of APF is effective in rendering harmonics compensation of supply currents by maintaining the total harmonic distortion (THD) at the PCC as per the specified IEEE Std. 519. Situations like load unbalancing and dynamic switching of nonlinear loads are undertaken to validate the performance of the APF in the considered system. The same is illustrated by extensive harmonic analysis and monitoring of various PCC electrical parameters.