Comparative Study of Power Quality Improvement Using Active and Passive Filters

Nonlinear loads draw non-sinusoidal currents due to the current harmonics generated by them. In modern power distribution systems, the majority of loads draw reactive power and/or harmonic currents from the AC source along with main active power currents. These nonunity power factor linear and nonlinear loads cause low efficiency of the power supply system, poor power factor, destruction of other equipment due to excessive stresses and EMI problems. Passive filter and Active power filter (APF) based on a simple control technique is used to provide reactive power and harmonics compensation for linear and nonlinear loads. This paper compares the working of these filters using MATLAB and simulink. The three- phase PWM-based voltage source inverter is applied to a distorted three-phase 500 kVA, 440 volt, 50 HZ power system under the steady state operating condition. Finally their simulated results of Source Voltage and Current, Filter Voltage and Current & Load Voltage and Current are compared and their respective THDs are obtained. Current wave THDs of power utility line are compared without filters, with Passive Filter and with Shunt Active Power Filter