Topology structure of power composite modular multilevel solid state transformer for AC/DC hybrid distribution network

Abstract

The invention discloses a power combination solid-state transformer topology structure for an alternating-current and direct-current hybrid power distribution network. The structure comprises a modular multi-level converter located on the high-voltage side, a high-frequency AC-DC converter on the middle side and an inverter on the low-voltage side. One branch is led out from a middle point of eachof upper and lower bridge arms of three phases of the modular multi-level converter is connected into a high-frequency transformer through a blocking capacitor to form a new high-frequency power circulation path, and meanwhile, a high-frequency component is superposed in a target modulation signal; energy on the high-frequency side is introduced into the high-frequency transformer in a form of high-frequency power through the high-frequency circulation path and is transmitted to the low-voltage side, so that an input stage of the high-voltage side and an isolation stage of the middle side aresubjected to integrated power conversion by adopting a power combination thought, the power conversion stage number is effectively reduced, the power conversion is more integrated, and the power transmission efficiency is higher. Meanwhile, the high-frequency transmission power does not flow to a high-voltage direct-current port and a base-frequency alternating-current port, and a frequency selection device such as a wave trap or the like is not needed.

Description

technical field [0001] The invention belongs to the technical field of high-voltage and high-power electric power electronics, and mainly relates to a power composite solid-state transformer topology structure for an AC-DC hybrid distribution network. Background technique [0002] In the traditional AC distribution network, the power transformer is the key equipment to realize voltage level conversion and electrical isolation, but due to its relatively single function, the need for a large amount of magnetic materials, and the inability to directly access or process DC power, it cannot meet the needs of future intelligent systems. Therefore, solid-state transformers based on fully controlled power electronic devices came into being. [0003] Solid-state transformers, also known as power electronic transformers, electronic power transformers or smart transformers, were rated as one of the ten most potential technologies by the MIT magazine in the United States in 2011, and ar...

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Problems solved by technology

[0005] Purpose of the invention: Aiming at the problems that the existing solid-state transformers have many conversion stages and low transmission efficiency, and the existing power-combined solid-state transformers rely on frequency selection devices, the present invention proposes a power-combined modularization system for AC-DC hybrid distribution network Multilevel Solid State Transformer Topology

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