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 to achieve complete decoupling control. The quality of the control effect depends too much on the mathematical model of the controlled object, and the control is relatively complex

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