Using the Instantaneous Power Theory in order to control the current in the parallel active filter to compensate reactive power and reduction of harmonics

Widespread use of nonlinear loads in electric power distribution has been caused numerous problems, including harmonics increase in the network. Although applying the passive filter to eliminate harmonics in the network is the most common method, with increase of semiconductor devices and development of power electronics, applying the active filter have been more prosperous. In this paper, the current control strategy in three-phase parallel active filter, with the Instantaneous Power Theory, to improve power quality through compensating harmonics and reactive power required by a nonlinear load, are presented. The pattern of PWM for converter switching is based on hysteresis band. The advantages of this approach is that compensation is only based on measured load current and supply voltage and don't need to know the harmonics and reactive power required by load.