Bi-direction direct-current solid-state transformer with high-frequency alternating-current isolation link

Abstract

The invention discloses a bi-direction direct-current solid-state transformer with a high-frequency alternating-current isolation link, and belongs to the technical field of electric power. The transformer is formed by connecting n identical direct-current transformer units at a low-voltage port in parallel and at a high-voltage port in series, wherein n is a positive integer larger than or equal to 2. Each direct-current transformer unit comprises two full-bridge transformers (H1 and H2), an auxiliary inductor (L), an isolation transformer (T) and two direct-current filter capacitors (C1 and C2), wherein the direct-current filter capacitors (C1 and C2) are connected with the direct-current ends of the full-bridge transformers (H1 and H2) respectively in parallel, the primary side and the secondary side of the isolation transformer are in parallel connection with the alternating current ends of the full-bridge transformers (H1 and H2) respectively, and the auxiliary inductor (L) is connected between the alternating current end of the full-bridge transformer H1 and the isolation transformer. Voltage matching of high-voltage and low-voltage direct-current links can be achieved, bi-direction flowing of power and electric isolation can be achieved, and the transformer has a certain application prospect in a direct-current power distribution network and a direct-current micro-grid.

Description

technical field [0001] The invention belongs to the technical field of electric power and relates to a solid-state transformer, in particular to a bidirectional DC solid-state transformer with a high-frequency AC isolation link. Background technique [0002] Due to its many advantages such as high modularity, high efficiency, high power density, low noise, and high intelligence, there have been many studies focusing on the use of power electronic transformers (also known as solid-state transformers SST) to replace traditional AC distribution transformers. Especially with the rapid development of distributed electric energy and energy storage in the smart grid, SST, as an integrated system of various distributed units, and a solution for flexible control of voltage and power flow, has received more and more attention. [0003] At present, the direct current transmission (VSC-HVDC) based on the voltage source converter (Voltage Source Converter, VSC) can independently and quic...

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Problems solved by technology

The patent "Input Series Output Parallel Automatic Voltage Equalizing DC Transformer Based on Full-Bridge Topology" proposes an isolated DC transformer for high-voltage input

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