A Novel Control Strategy of Shunt Active Filters

A shunt active filter injects a suitable non-sinusoidal current (compensating current) into the system at the point of common coupling and makes the source current sinusoidal. This paper presents a performance comparison of different methods of estimating reference-compensating current for a three-phase shunt active power filter. The control strategy considers the presence of harmonics in the system voltage and load current simultaneously. The shunt active filter provides current compensation, such that the compensated current drawn from the network is sinusoidal and balanced, corresponding to the fundamental positive-sequence component of the load current, plus an additional fundamental positive sequence component to cover losses in the power circuit of the shunt active filter. Simulation results are presented to validate the control strategy. Simulation results have determined that the Fast Fourier Transform method provides good steady state and transient responses for active filters in unbalanced systems.