Real-time testing of a fuzzy logic controller based grid-connected photovoltaic inverter system

This paper presents a novel fuzzy logic controller (FLC) based high performance control of a 3-phase photovoltaic (PV) inverter connected to the grid line. For the proposed control scheme one FLC is used for voltage control and two FLCs are used for current controls. With the aid of the developed inverter model and fuzzy voltage and current control schemes, the digital signal processing (DSP) controller board generates the sinusoidal pulse-width modulated (SPWM) logic signals for the inverter operation which regulates the 50 Hz sinusoidal ac output voltage and current for both standalone and grid-connected modes. A prototype PV grid connected 3-phase inverter controlled with the proposed FLCs is built using the DSP board DS 1104. The proposed fuzzy control strategy demonstrates stable ac output voltage of the inverter satisfactorily during both transient and steady-state conditions including grid and/or load disturbances. Moreover, the inverter is capable of feeding excess power to the grid when the power generation is more than local demand. The developed control system generates only 2.48% and 4.64% of output voltage and current total harmonic distortion (THD), respectively. The output waveform results such as the inverter output voltage, injected current, and the system power flow are presented to validate the effectiveness of the control system.