A modular solid-state transformer based on half-bridge cascaded three-level

Abstract

The invention provides a modular solid-state transformer based on a half-bridge cascade type three-level, wherein a sub-module unit and a DAB unit of the MMC are interconnected, Both the MMC submoduleand the DAB input use a half-bridge cascaded three-level structure. to reduce the number of modules required and the number of high frequency transformers. The AC side of DAB is connected in series with capacitors to isolate the DC component of the three-level output voltage, and the DAB output converter adopts a full-bridge structure, which forms a low-voltage DC bus bar through a plurality of DAB outputs in parallel, and a three-phase full-bridge inverter is connected to the low-voltage DC bus bar and forms a low-voltage AC port. The application of the topology of the invention can realizethe interconnection of the distribution network with multi-voltage levels and various ACDC forms, thereby laying the equipment foundation for the construction of the intelligent distribution network in the future.

Description

technical field [0001] The present invention relates to the fields of intelligent distribution network technology and power electronics technology in power systems, and in particular relates to a new modular solid-state transformer topology using half-bridge cascaded three-level sub-modules, which can be applied to realize multi-voltage levels and multiple Distribution network interconnection in the form of AC and DC. Background technique [0002] Renewable energy is often connected to the distribution network in the form of distributed power and converted into electrical energy for end users. However, the operation mode of the traditional distribution network is basically based on the supplier-led, one-way radial power supply, and its power distribution primary control equipment (on-load voltage regulator, contact switch, etc.) And the high-precision real-time operation optimization requirements of the distribution network when the load fluctuates frequently, and the acces...

AI Technical Summary

Problems solved by technology

However, the power transmission between the medium voltage network and the low voltage network of this topology needs to be carried out through the medium voltage DC bus, resulting in a large current stress on the MMC switching device.

In addition, additional series capacitors are required on the medium-voltage DC bus to realize MMC and DAB, which increases the cost of the device

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