Single-Phase Two-Stage Transformerless Grid-Connected Inverter for Photovoltaic Applications

This paper introduces a single dc source five-level grid-tied photovoltaic (PV) inverter. In the proposed topology generates a five-level output voltage waveform using only one input dc source. It causes reduction in the overall size and cost. In addition, the dc-dc buck-boost converter is applied to regulate the voltage of the utilized capacitor around it's reference value. The adjusted capacitor voltage leads to high quality output voltage and current. The output five-level voltage is favorable in high voltage applications and it generates lower total harmonic distortion (THD) in comparison with three-level inverters. In addition to these advantages, the presented topology is capable of providing reactive power supporting which is essential according to grid regulations. Peak current control (PCC) method is used to control both active and reactive powers. Also, in the in order to generate the switching gate pulses of the introduced inverter the PCC strategy is applied. In addition, a completely controlled sinusoidal current can be pumped to the power grid. In order to highlight the advantages of the proposed system, the proposed inverter is compared with other topologies. The effectiveness of the introduced configuration is validated by MATLAB/Simulink when, the proposed topology is connected to the power grid. Finally, the paper is concluded.