MODULAR MULTILEVEL CONVERTER-BASED TRANSFORMERLESS SOLAR POWER INVERTER TOPOLOGICAL STRUCTURE

摘要

A modular multilevel converter (MMC)-based solar power inverter topological structure. The structure comprises: a photovoltaic array, direct current (DC) conversion circuits, and inverters formed by multiple standard power units. A DC voltage generated by the photovoltaic array is converted by the DC conversion circuits into a stable DC voltage, and then used as a DC side voltage by the standard power units in the inverters. By controlling the switching of switch elements of the power units, the inverters allow a three-phase alternating high voltage output to be integrated into a power grid. The topological structure obviates the need for the arrangement of a transformer on the grid-connection side of a photovoltaic power generation system, and achieves the high voltage output by stacking a plurality of standard power units. Also, the topological structure is inexpensive, compact, structurally simple, and highly responsive.