This paper deals with a shunt active power filter (APF) realized using three-phase p-q (3-φ p-q) theory and single-phase p-q (1-φ p-q) theory approaches. A comparative evaluation between two p-q theories, applied to three-phase three-wire system, is presented. An in-depth simulation study is carried out for better understanding of the concepts and to explore the factors that affect the performance of both the theories. A shunt APF system is developed and tested using a DSP DS1104 of dSPACE. An extensive experimental investigation is carried out under balanced and/or unbalanced supply voltages, and balanced and/or unbalanced load conditions. It is found that both the p-q theories perform well under balanced supply voltages and balanced non-linear load condition, but, their performance degrades when supply voltages are highly distorted. The 3-φ p-q theory has advantage over 1-φ p-q theory when the load is unbalanced in nature. However, under unbalanced voltages, 3-φ p-q theory fails to demonstrate its ability to compensate the load current harmonics and reactive power, whereas, 1-φ p-q theory gives better performance.
