Reactive and harmonic current compensation for unbalanced three-phase systems using the synchronous detection method

Abstract This paper presents the application of the synchronous detection method for reactive and harmonic current compensation in an unbalanced three-phase power system. When the instantaneous power theory is applied, a balanced three-phase voltage source is required. However, in practical distribution systems, it is difficult to maintain balanced three-phase voltage along the feeder lines. To handle the reactive and harmonic current compensation in an unbalanced voltage source, the synchronous detection method is applied by per-phase calculation to obtain proper compensating components. Three different approaches using equal power, equal line current, and equal load resistance concepts in the synchronous detection method are discussed. Formulations and calculation algorithms are derived for each approach. By simulation, it is proved that the synchronous detection method is effective in unbalanced system compensation and gives a better performance than the instantaneous power theory. In this paper, preliminary results from simulations are obtained. Using the different approaches of the synchronous detection method, the line loss after compensation can also be minimized.