A frequency adaptive control scheme for a three-phase shunt active power filter

The propagation of nonlinear loads and distributed power generation systems can cause power quality problems such as harmonic distortion, system imbalance, and resonance problems. Shunt active power filters are used to eliminate these power quality problems. A recently proposed control scheme for a shunt active power filter utilized a time-domain transformation to extract positive and negative sequence components of the system voltages and currents. These components are used in a modified version of instantaneous reactive power theory to calculate the reference currents for a three-phase inverter. Changes in the system operating conditions can cause the system frequency to vary, which can impact the performance of the time-domain transformation. Proposed in this paper is a frequency adaptive control scheme to compensate for frequency variations. Several simulation and experimental tests have been performed to validate the operation of the proposed frequency adaptive control scheme.