The Comparative Study of Instantaneous Power Theory in Three-Phase Three-Wire Systems

The main objective of this paper is to investigate the compensation features of switching compensator in three-phase three-wire systems as instantaneous real oscillating power, which is defined in p-q theory as the compensation goal. This compensation goal should be paid special attention when involving torque oscillation or frequency variation in week systems. The relationship between compensator current and the original supply current is highlighted by employing Current’s Physical Components (CPC) power theory as the analytic tool. This paper demonstrates that in three-phase three-wire systems, there are numerous kinds of compensator currents to reach this compensation goal, including the compensator current derived from p-q theory or CPC theory. The former uses the minimum size of energy storage elements than any other kinds of current. While the latter improves the quality of the load by reducing its unbalanced current and harmonics.