Speeding-up dynamic response of active power conditioners

The i/sub d/-i/sub q/ control method is one of the most widespread control methods for active power filters. Two improvements to this method are presented: the elimination of the PLL (phase locked loop) in active power filters for harmonic current compensation only and a strategy for achieving the best transient time. PLL elimination is an important simplification for reducing the computational effort in a digital implementation as well as for improving transient time. The achievement of the best transient time is essential for an efficient compensation of currents with time-varying harmonic content. The paper describes both improvements and presents simulations and experimental results.