Third order sinusoidal integrator (TOSSI)-based control algorithm for shunt active power filter under distorted and unbalanced voltage conditions

The performance of a shunt active power filter (SAPF) essentially depends on the accuracy of synchronization and harmonic components extraction. The conventional algorithms such as synchronous reference frame theory and instantaneous reactive power theory work well under sinusoidal and balanced grid voltage conditions. This research is mainly aimed at enhancing the performance of the SAPF when the grid voltages are unbalanced and distorted. The synchronizing signals of the voltage at the point of common coupling (PCC) and system frequency are extracted from the distorted voltages using third order sinusoidal signal integrator (TOSSI) based frequency adaptive pre-filters. In this study, the TOSSI-based filter is used to extract current harmonic components from the load current which increases the selectivity and the dynamic performance of extraction process. The performance of the proposed control approach for a SAPF under distorted and unbalanced voltage conditions is demonstrated through computer simulations and validated by experimental results.