Five-level cascaded active filter for power line conditioners

This paper presents a five-level cascaded multilevel Voltage Source Inverter (VSI) based shunt active filter for Power Line Conditioners (PLC) to improve power quality. The reference current extraction is based on sensing main currents that are multiplied with estimated peak reference current. The proposed approach comprises Low Pass Filter (LPF) in conjunction with Proportional Integral (PI) controller is used to estimate the peak reference current and maintain the DC-bus capacitor voltage of the inverter nearly constant. The cascaded multilevel active filter switching signals are derived from proposed triangular carrier current modulator; it gives better dynamic performance under transient and steady state operating conditions. The APLC system is validated through extensive simulation under steady state and transient condition with different non-linear loads. These simulation results reveal that the cascaded active filter effetely compensates the current harmonics and reactive volt amperes.