Novel photovoltaic grid-connected system based on modularized multi-level converter

The invention discloses a novel photovoltaic grid-connected system based on a modularized multi-level converter. Each phase of the modularized multi-level converter is formed by connecting N sub-modules in series. High voltage and high power level can be realized without directly connecting devices in series. The novel photovoltaic grid-connected system is mainly applied to a high-voltage direct-current transmission system and a feed-in grid system of a wind power station at present. According to the novel photovoltaic grid-connected system provided by the invention, the modularized multi-level converter is applied to the photovoltaic grid-connected system, and is combined with a DC (Direct-Current)-DC converting circuit by combining the requirements and the characteristics of the photovoltaic grid-connected system, so that the novel photovoltaic grid-connected system based on the modularized multi-level converter is constructed. When a level value is relatively high, the quantity of required devices as the DC-AC (Alternating-Current) converting circuit is used is less than that of the required devices as an embedded multi-level converter is used, so that the control manner is simplified.