A series active power filter which compensates current harmonics and voltage unbalance simultaneously

An active power filter connected in series to the power distribution system is presented and analyzed in this paper. The series active power filter is implemented with a PWM voltage-source inverter and operates in conjunction with a resonant LC filter connected in parallel to the power lines and is able to compensate current harmonics and the fundamental negative and zero sequence voltage components generated by nonlinear unbalanced loads. The proposed series active power filter also compensates zero sequence current harmonic components that flow through the neutral conductor. In particular, the active power filter is discussed in terms of the principles of operations under steady-state and transient operating conditions. The design of the power and control circuits are reported