A single-phase multi-module cascaded solid-state transformer voltage equalization power control method

Abstract

The invention discloses a single-phase multi-module cascaded solid-state transformer voltage equalization and power control method. The power main circuit part of the single-phase solid-state transformer consists of three stages: AC / DC rectification input stage, DC / DC intermediate stage and DC / AC output stage. composition. The control design of the rectifier stage and the intermediate stage is carried out as a system. The input stage adopts a common duty cycle control strategy based on single-phase d-q vector control, and the output DC voltage of the intermediate stage is used as the feedback value of the outer loop voltage loop to realize the output of the intermediate stage. The stability of the voltage and the unit power factor of the input terminal of the grid; each module of the intermediate stage introduces a control strategy based on voltage feedforward and feedback at the same time, and the voltage feedforward is used as the reference of the voltage feedback, and their errors are output by the voltage PI regulator as The reference of the current inner loop of the module; the two control strategies of the front stage and the middle stage interact to realize the voltage and power balance of each module of the SST, the unit power factor of the grid side, the high sinusoidal degree of the grid current, the low voltage stress of the switch tube, and the output of the middle stage Features such as small DC voltage ripple.

Description

technical field [0001] The invention relates to the application of power electronics technology in power systems, in particular to a multi-module cascaded SST (solid-state transformer) voltage equalization and power control method. Background technique [0002] Since the traditional power transformer was invented, it has become an indispensable and important part of the power system because of its reliable operation and simple structure, and has a huge number of applications. But it has significant disadvantages: bulky, bulky; output voltage cannot be maintained constant, etc. Its main function is to realize isolation and voltage level transformation, the function is simple, and it has no ability to improve the power quality of the grid. [0003] The concept of solid-state transformer has long been proposed, and it mainly realizes voltage conversion and energy transfer by using power electronic devices and power electronic technology. Its outstanding feature is that it can...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a single-phase multi-module cascaded solid-state transformer voltage equalization power control method for the shortage of unbalanced voltage and power existing in the existing cascaded modules

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