Real-Time Control of Shunt Active Power Filter under Distorted Grid Voltage and Unbalanced Load Condition Using Self Tuning Filter

In this study, an alternative control method is proposed to improve the harmonic suppression efficiency of the active power filter in a distorted and unbalanced power system to compensate the perturbations caused by unbalanced non-linear loads. The proposed method uses a selftuning filter (STF) to process the grid voltage in order to provide a uniform reference voltage to obtain the correct angular position of the phase locked loop. Moreover, the required compensation currents are obtained by implementing another STF to the transformed set of currents in order to separate the fundamental and harmonic currents. This allows the calculation of precise reference current for unbalanced, non-linear and variable load conditions. The proposed control method gives an adequate compensating current reference even for non ideal voltage and unbalanced current conditions. The realtime control of the filter under the distorted and unbalanced power system is developed in RT-LAB realtime platform. Results obtained in the SIL (software-in-the-loop) configuration are presented to verify the effectiveness of the proposed control technique.