A Hybrid Compensation System Combining a Parallel LC Filter and a Shunt Active Power Filter Using Load-Conductance-Signal Control

This paper investigates a hybrid active power filter (HAPF) composed of a shunt active power filter (SAPF) connected in parallel with an LC passive filter designed according to the Currents’ Physical Components (CPC) theory. Importantly, the SAPF operates using a load-conductance-signal control strategy in which the DC-link capacitor voltage is not regulated around a fixed reference value. Instead, it reflects the instantaneous power balance within the source-filter-load system and is used to generate the source-current reference. The present study focuses on maintaining the distortion of this signal at the lowest possible level, since its quality directly affects the performance of the filtering system. The hybrid configuration reduced source-current THD to approximately 2% in all phases, compared with values of up to 14% for stand-alone SAPF operation. Moreover, the THD of the DC-link voltage decreased from 85% to 4%. The results demonstrate that CPC-based passive balancing combined with conductance-controlled active filtering improves both compensation effectiveness and SAPF operating conditions.