A Novel Active Power Filter for Supraharmonic Emissions of Single Phase Grid-Connected Inverters

Conventional active power filters (APFs) are not appropriate to reduce the emissions of grid connected converters in supraharmonic (SH) range due to many limitations. Consequently, this article presents a novel APF designed for reducing the SH emissions of single-phase grid-connected inverters (GCIs). The new design solves many obstacles that limit the usage of conventional APFs to filter out the SH emissions of GCIs as: The switching frequency of the proposed APF is same as the one used with the GCI, excluding the need for harmonic current calculation, a simple current controller is used based on a proportional resonance controller, multiple distributed filtering bandwidths are acquired, a simple design criteria for the APF power circuit is required, in addition to that, there is no need for higher ordered coupling passive filters for both GCI and APF. The proposed approach is also superior in its performance than its counterparts that are used to mitigate the SH emissions of GCIs. A mathematical analysis is performed to describe the GCI emissions in SH range and to give the basic principles of filtering. The performance of the proposed APF is verified through simulation and experimental studies.