Active Filter for Harmonic Reduction

In the modern power distribution system, majority of loads draw reactive power and harmonic currents from ac source along with main power currents. These non-unity power factor linear and non-linear loads cause low efficiency of supply system, poor power-factor, destruction of other equipments due to excessive stresses and EM1 problems. Active filters have been considered an effective solution to reduce these problems. This paper presents an Active Power Filter (APF) based on simple control technique to provide reactive power and harmonics compensation for linear and non-linear single-phase loads. A voltage source inverter with carrier less hysteresis PWM current control is used to form an APF. A simple P-l proportional-integral) dc bus voltage controller with reduced energy storage capacitor is employed in the APF.