Novel modular multi-level solid-state transformer and internal model control method thereof

Abstract

The invention provides a novel modular multi-level solid-state transformer and an internal model control method thereof. The solid-state transformer comprises a modular multi-level converter, a DC-DC isolator and a DC-AC inverter, wherein the alternating current side of the modular multi-level converter is connected to a high-voltage AC network and the direct current side of the modular multi-level converter is connected to the input end of the DC-DC isolator; the direct current side of the DC-AC inverter is connected to the output end of the DC-DC isolator and the alternating current side of the DC-AC inverter is connected to a low-voltage AC network or load; through changing the number of power sub-modules connected to each bridge arm of the modular multi-level solid-state transformer in series, the voltage application range of the solid-state transformer is flexibly adjusted, and a problem of application of the solid-state transformer in middle-high voltage occasions is effectively solved. According to the characteristics of internal model control, an internal model current inner loop is combined with a PI voltage outer loop, and a new double closed loop control structure is constructed, so that the modular multi-level converter and the DC-AC inverter are controlled; and through the control method, the current has a quicker response speed and stronger anti-disturbance capability.

Description

technical field [0001] The invention relates to a solid state transformer (SolidStateTransformer, SST), in particular to a novel modular multilevel solid state transformer (MMC-SST) and an internal model control method thereof. Background technique [0002] Solid-state transformer is a new type of intelligent power transformer based on high-power power electronic conversion technology to realize voltage conversion and energy transfer. With the proposal and development of energy interconnection systems, solid-state transformers, as their key equipment power routers, have received more and more attention. [0003] So far, some research results have been obtained at home and abroad on the realization scheme and control method of the topology structure of SST. At present, solid-state transformers mainly include traditional two-level or three-level VSC (Voltage Source Converter) type solid-state transformers and H-bridge cascaded multi-level solid-state transformers. However, t...

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Problems solved by technology

Although the system has good response performance, due to the need for cross-decoupling and the feedback decoupling effect is sensitive to parameter changes, it is difficult ...

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