Current harmonics reduction using sliding mode control based shunt active power filter

Use of power electronic devices creates the power quality issues by generating harmonics and reactive power in the utility system. Active power filter is one of the best solution to reduce the harmonics level in the system. In this paper single phase shunt active filter using sliding mode control is implemented in MATLAB/Simulink. Sliding mode controller acts as a current controller to control filter inductor current by providing harmonics and reactive current required by the load. The switching signals to the shunt active power filter is generated based on the sliding surface and the source voltage. PI controller is used to control DC link voltage of active power filter along with generation of reference source current. Performance of proposed shunt active filter is analyzed under nonlinear and combined non-linear and linear load. It is observed that shunt active power filter improves the total harmonic distortion (THD) and power factor under variable load condition.

I. Introduction

Excessive use of power converters and other nonlinear loads introduces harmonics in network and draws reactive power current from supply. The increase in the reactive power, non-sinusoidal supply voltage and current in power distribution result in many adverse effect such as overheating, poor efficiency, instability, disturbance to other consumer equipment, interference with communication equipment etc. Conventionally passive filters are used to improve power quality but it has various disadvantages of fixed compensation, bulky inductor, no isolation between input and output and resonance [1]. Active power filters are good solution, since they can compensate for reactive power and also solve the harmonic problem. There are two types of active filters: Shunt active power filter & Series active power filter. Shunt APF used to improve shape of source current, whereas series APF can compensate for voltage harmonics and unbalance. Shunt active filter are widely used as they effectively doing compensation and current rating is much less as compared to series filter as it is connected in parallel [2]–[5].