Control of series active power filters compensating for source voltage unbalance and current harmonics

In this paper, a novel control scheme compensating source voltage unbalance and current harmonics for hybrid active power filters is proposed. The reference voltage for compensation is derived from the differences between the fundamental source and load voltages and their instantaneous values, where the positive sequence component which is simply obtained by using digital all-pass filters is used as the fundamental voltages. The reference voltages for the 5^th and 7^th harmonic compensation are predicted a sampling period ahead to reduce the delay in the inverter voltage control loop. The validity of the proposed scheme has been verified by experimental results