Comparison of different control strategy of conventional and digital controller for active power line conditioner (APLC) for harmonic compensation

Various electronic circuits such as inverters, choppers, cyclo-converters, SMPS used by industrial and domestic purposes are non-linear in nature, which makes the load current to be distorted, causing undesirable effects like heating, equipment damages, EMI related problems in power system. The active power filter (APF) is the best solution for eliminating the harmonics caused by the non-linear loads. This paper presents about a three-phase four-wire active power filter for power line conditioning to improve power quality in the distribution network and implementation of a digitally controlled APF. The active power filter is implemented with PWM based current controlled voltage source inverter (VSI).The switching signals for APF are generated through proposed three-level hysteresis current controller (HCC). The shunt APF system is modeled and investigated under different unbalanced non-linear load conditions using MATLAB program. The Controller Design using Hardware Description Language (VHDL or VERILOG) becomes independent of process technology. Synchronous reference frame (SRF) is used for generation of reference current. Both PI current algorithm and HCC are written in VHDL code and implemented using FPGA platform.

I. INTRODUCTION

The voltage source inverter has three coupling inductors in series in the ac-side and an energy storage capacitor on the dc-side. Similarly, the current source inverter has three coupling capacitors in parallel in the ac-side and an energy storage inductor in series with the dc-side. In general the voltage source inverter type is preferred for the shunt active power circuit due to the lower losses in the dc-side and it is possible to create multilevel inverter topologies for high power level applications. [1]–[6]