Selective disturbance compensation and comparisons of active filtering strategies

This paper presents an alternative method to evaluate selectively disturbance compensation. Instantaneous decompositions to be applied directly on voltages and current signals are used to identify the distorting and unbalancing components, and can be used to compensate either nonactive power, power oscillations, harmonics and load imbalances in a different way as provided by the traditional pq theory. Three control strategies of active filters were tested and compared for solving typical power quality problems. Simulation results are presented to show the main differences among the control strategies facing nonlinear, unsymmetrical and variable loads under generic voltage conditions. According to these results, it is shown that some shunt active filtering strategies can even improve the PCC voltages under resonance conditions.