A hybrid solution to active power filter for the purpose of harmonic suppression and resonance damping

Active power filters (APFs) have been intensively explored over the past decade. Various topologies and control schemes have been documented aiming at reducing the cost and improving the performance of the harmonic compensation system. This paper highlights the essence of the mechanisms of diverse APFs by using the concepts of controllable sources. Four basic active units for comprehensive APFs can be employed in the circuit branch to control the impedance of the branch. This paper also presents a general principle for constructing new hybrid APFs to suppress harmonics. The principle can be easily used to find new approaches for cost-effective hybrid APFs. One hybrid solution is provided in this paper.