Analysis and comparison of passive & active harmonic suppression filters in distribution systems

In typical distribution systems, the proliferation of nonlinear loads results in deterioration of the power quality. Standards such as the IEEE-519 are imposing harmonic limits for end users and utility systems. Passive filters have been commonly applied to limit the flow of harmonic current in distribution systems. However they introduce resonance in the power system. They also tend to be bulky, particularly if the number of harmonic components to be cancelled increases. Active filters have been developed to provide better performance. Some design considerations are outlined in the paper, such as real-time emulation of tuned LC filter, selective harmonic elimination based on harmonic rotating frames, and instantaneous total harmonic cancellation. Some experimental results are included.