Solid-state transformer topology family applied to alternating-current and direct-current hybrid power distribution network and design method

Abstract

The invention provides a solid-state transformer topology family applied to a direct-current and alternating-current hybrid power distribution network. The direct-current end of a sub-module of a modular multilevel converter and the input end of each isolated dual-active-bridge converter are interconnected to form a modular structure, the output ends of the multiple isolated dual-active-bridge converters are connected in parallel to form a low-voltage direct-current bus, and a three-phase full-bridge inverter is connected to the low-voltage direct-current bus to provide medium-voltage direct-current, medium-voltage alternating-current, low-voltage direct-current and low-voltage alternating-current ports, so the four kinds of ports are suitable for interconnection of multi-voltage-level polymorphic alternating-current and direct-current hybrid power distribution networks. The invention further provides a design method of the solid-state transformer topology family, so that the number ofsub-modules and the number of high-frequency transformers in the solid-state transformer device are reduced on the premise of obtaining the solid-state transformer device meeting specific scene requirements, and the size and the cost are reduced.

Description

technical field [0001] The invention relates to the fields of intelligent distribution network technology and power electronics technology in power systems, and in particular relates to a modular solid-state transformer topology family and design method applied to an AC-DC hybrid distribution network. Background technique [0002] The future power distribution system has the characteristics of high proportion of distributed power supply and flexible load (electric vehicle, distributed energy storage) access, high power quality of users and customization requirements of various power forms, and the proposal of ubiquitous electric power Internet of things makes The new-generation energy system with the grid as the core and the efficient integration of multiple energy sources puts forward higher requirements for the flexibility, controllability and resilience of the distribution network. However, the operation mode of the traditional distribution network is basically based on t...

AI Technical Summary

Problems solved by technology

Compared with the three-phase half-bridge cascaded power electronic transformer, this topology improves the quality of the DC output voltage and significantly reduces the amount of high-frequency transformers and power electronic switching devices, but the medium-voltage network and low-voltage network of this topology need to pass through Medium-voltage DC bus for power transfer, resulting in high current stress on MMC switching devices

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

Therefore, there is a large room for optimization in this topology

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