Modularized photovoltaic energy storage system

Abstract

The invention provides a modularized photovoltaic energy storage system, wherein the output ends of energy storage cell units are connected with direct current bus input ends of half-bridge modules to form multiple energy storage cells; the alternating current output sides of the multiple energy storage units are connected in series and then connected with electric reactors in series to form a one-phase half-bridge arm; two half-bridge arms are connected in series to form a one-phase overall bridge arm, and three bridge arms form three-phase bridge arms in the manner; the upper ends of the three bridge arms are connected to form the direct current bus positive end of the photovoltaic energy storage system; the lower ends of the three bridge arms are connected to form the direct current bus negative end of the photovoltaic energy storage system; the connecting points of the upper bridge arm and the lower bridge arm of the three-phase bridge arms, namely the three middle points of the three bridge arms are led out to form an alternating current port of the photovoltaic energy storage system; and the output positive end and the output negative end of a photovoltaic group string are connected with the direct current bus negative end and the direct current bus negative end of the photovoltaic energy storage system for transmitting voltage. The modularized photovoltaic energy storage system is based on a modularized multi-level structure; the modularized photovoltaic energy storage system is provided with the alternating current port, the direct current port and the cell port, so that the modularized photovoltaic energy storage system can be connected with a photovoltaic module, an energy storage cell and an alternating current power grid at the same time.

Description

technical field [0001] The invention relates to a photovoltaic and energy storage integrated system in the field of new energy power generation, in particular to a modular photovoltaic energy storage system. Background technique [0002] As a clean and widely sourced renewable energy, photovoltaic power generation technology is receiving widespread attention and favor from all over the world. At the same time, due to the volatility of photovoltaic power generation itself, large-scale access to the power grid has brought certain impacts on the stable operation of the power grid. Combining energy storage with photovoltaic power generation is an effective means to stabilize photovoltaic volatility and solve its grid connection problem. [0003] At present, there are two main forms of combining photovoltaic power generation and energy storage: [0004] The first is that the energy storage system and the photovoltaic power generation system are connected on the AC side. In the...

AI Technical Summary

Problems solved by technology

The efficiency is better than the second method, but the cost of the three-phase isolated energy storage converter in this method is much higher than that of the non-isolated DC / DC converter in the second method

[0009] In the second method, no matter whether the electric energy of the energy storage system is output to the grid or imported from the grid, it needs to undergo two-stage conversion, and the efficiency is usually lower than that of the first method.

[0010] Each level of energy conversion brings efficiency loss and also means an increase in hardware cost

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