Comparison of two compensation control strategies for shunt active power filter in three-phase four-wire system

Due to a large amount of non-linear power electronic equipments, impact and fluctuating loads (such as that of arc furnace, heavy merchant mill and electric locomotive, etc), problems of power quality have become more and more serious with each passing day, as a result Active power filter (APF) gains much more attention due to excellent harmonic compensation. But still the performance of the active filter seems to be in contradictions with different control strategies. This paper presents detailed analysis to compare and elevate the performance of two control strategies for extracting reference currents of shunt active filters under distorted and unbalanced conditions. The well known methods, instantaneous real active and reactive power method (p-q) and active and reactive current method (i_d-i_q) are two control methods which are extensively used in active filters. On owing i_d - i_q method gives away an outstanding performance under any voltage conditions (balanced, un-balanced, balanced non-sinusoidal and balanced sinusoidal with different main frequencies). Extensive simulations were carried out; simulation results validate the superior performance of active and reactive method (i_d - i_q).