A Grid-Connected Photovoltaic Power Conversion System with Solid-State Transformer

This paper presents a new method to connect a photovoltaic (PV) system to the grid. The integration of the photovoltaic system into the grid is implemented using a solid-state transformer (SST). The SST consists of three main stages: medium voltage stage, isolation stage, and low voltage stage. In order to integrate the photovoltaic system as the main source, we use transformer multi-port. Furthermore, in order to transfer the maximum power to the grid, Maximum Power Point Tracking (MPPT) algorithms, have been incorporated. A modular multilevel converter (MMC) has been proposed on the medium voltage side. To control the MMC voltage a capacitor voltage balancing technique has been applied. In MATLAB / Simulink, The performances of the presented system have been studied. The results showed the efficiency of the proposed balancing method of the MMC and dynamic performance of grid connected PV systems.