Smart impedance application on unbalanced harmonic mitigation in three-phase four-wire systems

This paper describes the newest hybrid active filter topology, the Smart Impedance, under unbalanced harmonic mitigation in three-phase four-wire systems. A three-phase modular approach permits the selective compensation of unbalanced harmonic components, no matter the current imbalance level or the harmonic sequence components flowing through the line. The Smart Impedance effectiveness highlights its capability of mitigating harmonics from voltage-source or current-source nonlinear loads emerging as an option to Parallel Active Filter or Parallel Passive Filter and classical hybrid active filter. The control algorithm is based on Proportional Resonant Controller. Practical results demonstrate the effectiveness of the Smart Impedance topology under unbalanced and different load conditions.