Operation of PV Inverter as Active Filter Under Different Loading and Supply Conditions

This paper presents the design of a PV inverter control with added active filter (AF) functionalities, which is analysed for different voltage supply conditions and under different loading conditions. Three modes of operation are considered: a) at a unity power factor (PF), when inverter maximizes active power output, b) at set displacement PF, when inverter reduces active power output to provide compensation of fundamental reactive power, and c) at set PF and with active filter functionalities, when inverter reduces active power output to provide both compensation of reactive power and mitigation of harmonic emission in a local network. The reduction of maximum active power output is quantified in terms of fundamental reactive power (Q compensation) and both active and non-active non-fundamental power (compensation of distortion power) and graphically illustrated. Local harmonic emission is modelled using constant harmonic current sources and three-phase uncontrolled rectifier load, while grid voltage is modelled with purely sinusoidal and distorted waveforms, as well as with and without source impedance.