Shunt Active Power Filter for Harmonics Compensation Based on Three Phase Voltage Source Inverters

Abstract

Power quality of the power distribution systems have degraded because of the extensive use of power electronic devices. These nonlinear loads cause non-sinusoidal currents & voltages with harmonic components. Some of the major power quality issues due to non-sinusoidal currents and voltage with harmonic component are impact on power capacitor, Transformer, motors, telecommunication, energy and demand metering etc. Shunt active power filters (SAPF) are used to acquire balanced and sinusoidal supply currents via way of means of injecting compensation current. There are two major control loop namely outer control loop and inner outer loop with one extra loop. The outer control loop measures source current and voltage & generates the reference reactive & active power that to be compensated by the SAPF. The inner control loop effectively tracks the reference compensating currents in d-q coordinate using PI controllers. While extra loop is associated with capacitor of voltage source inverter (VSI). The constant voltage across the capacitor is maintained. So, there is active power loss which is achieved by comparing reference voltage with the standard voltage and send the error to the PI controller. Simulation results are obtained from MATLAB/Simulink under various non-linear load conditions. The cases considered here are as follows: i) 3 phase 3 wire full wave rectifier with varying load: The MATLAB/Simulink was developed and tested with load and result was compared with the traditional approach without harmonics compensation. The THD level is within limit as per IEEE 516 standard. ii) Different loading conditions: Same process as of case i) was performed and results are within limit as per IEEE 516 standard.