Battery energy storage topology structure without transformer based on MMC modularized multi-level inverter

Abstract

The present invention relates to a battery energy storage topology structure without the transformer based on MMC modularized multi-level inverter: every phase is connected in series with several subunits which are composed of half-bridge power modules and battery energy storage modules, and get access to the electrical network through buffer inductance. The half-bridge power module is formed by the series connection of an even number of n power units, which is divided into two groups, the upper group and the lower group; the number of each group's power units is n/2; the number of output phase voltage level step is n/2 + 1; the number of line voltage level step is n + 1; the output terminal of every phase is the midpoint of two groups of units, and the output terminal is connected with each group of unit by coupling inductance or uncoupling inductance. The power unit is in a half-bridge structure. As the topology is in parallel connection with electrical network, the electric power pollution of electric network can be inhibited; and the topology can make up for the instability of photovoltaic or wind energy generation to provide uninterrupted, clean, stable and high-qualified sine wave voltage of no frequency discontinuity to the load of the electrical network.

Description

technical field [0001] The invention relates to a transformerless battery energy storage topology based on an MMC (Modular Multilevel Converter) modular multilevel inverter, which can be used in the field of high-voltage power systems, so that the power grid can supply loads with reliable and high-quality voltage. Background technique [0002] At present, there are at least the following nine problems in the power grid: power failure, lightning spike, surge, frequency oscillation, voltage mutation, voltage fluctuation, frequency drift, voltage drop, pulse interference, etc. The electric energy generated by renewable energy such as photovoltaic or wind energy is also extremely unstable. The larger the scale of new energy grid-connected applications, the less secure the grid will be. According to the practice of grid-connected wind power plants at home and abroad, new The balanced output of energy generation power enables large-scale wind power and solar power to be easily and...

AI Technical Summary

Problems solved by technology

[0003] At present, power energy storage equipment is connected in parallel with the power grid through a transformer. The use of a transformer makes the equipment a large investment, occupies a large area, high cost, and a long production cycle.

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