Direct coupling of power active filters with photovoltaic generation systems with improved MPPT capability

Photovoltaic sources can be usefully combined with power active filters in order to regulate both the active and the reactive power injected into the mains. In this way, the system is able to compensate undesired load characteristics such as phase unbalances, power flickers, and low-order current harmonics, improving the power quality. In order to avoid an intermediate DC-DC chopper, a direct coupling between the PV panels and the DC-link of the voltage source inverter is considered in this paper. The DC-link voltage is continuously regulated between upper and lower limits for tracking the maximum power point of the PV panels. The proposed MPPT algorithm is based on real-time processing of current and voltage ripple of the PV source that is generated by the switching operation of the PWM inverter. The system performance is investigated emphasizing the transient behavior in presence of sudden variations of the solar irradiance. The theoretical developments are verified by realistic numerical simulations.