Multi-Modular Cascaded phase-shifted full-bridge converter for DC grid connection of Large-Scale Photovoltaic Power Systems

At present, the grid connection of most Large-Scale Photovoltaic Power Systems is AC grid, which has some obvious disadvantages. Firstly, a large number of low-voltage DC-AC inverters are used to connect Solar panels with the grid, which lead to high cost and switching loss. Secondly, the line loss inside the system is huge, since the low AC voltage of the grid lead to the high current. In this paper a novel DC grid connecting photovoltaic power system is introduced, in which the MPPT Control is realized by the cascaded high power phase-shifted full-bridge DC-DC modules. In the novel system the DC grid is supported by cascaded phase-shifted full-bridge DC-DC modules. Since the high-voltage DC grid connection and phase-shifted full-bridge DC-DC modules, the loss of the line and switching of system can be greatly reduced and the efficiency of the Photovoltaic Power Systems is improved. In this paper, firstly, it is focused on the topology and optimization of MPPT control of the cascaded phase-shifted full-bridge DC-DC module. Secondly, the interaction between cascaded modules and the dynamic response of the MPPT of the novel system are researched and is verified by the simulation.