Voltage and power balance control method for modular power electric transformer

Abstract

The invention discloses a voltage and power balance control method for a modular power electric transformer. The power electric transformer to which the method is applied to comprises an input stage, an isolation stage and an output stage; the input stage adopts common duty ratio control based on single phase dp decoupling, so that stable control of high voltage side direct current voltage and flexible adjustment of sine and power factors of input current are achieved; the isolation stage adopts a voltage power double loop control strategy without a current sensor, the output voltage outer loop adjustment generates a unified reference value of each power inner loop, and the adjustment of each power inner loop generates a phase shifting angle of each module of the isolation stage; and two types of control strategies of the input stage and the isolation stage act synergistically, so that voltage and power balance of each module of the power electric transformer is achieved.

Description

technical field [0001] The invention relates to the application of power electronics technology in power systems, in particular to a voltage and power balance control method of a modularized power electronic transformer. Background technique [0002] Power transformers have been used for more than a hundred years. Because of their high reliability and simple structure, they occupy an important position in today's power transmission and distribution systems, and their applications are huge. However, its main function is to achieve basic voltage level conversion and electrical isolation, and its functions are relatively single, and there are a series of disadvantages: large volume and weight; insulating oil poses a threat to the environment; it cannot maintain output voltage stability and improve power quality. [0003] The concept of power electronic transformer was proposed as early as the 1970s, mainly through power electronic technology and magnetic coupling technology to ...

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Problems solved by technology

However, its main function is to realize the basic voltage level conversion and electrical isolation. The function is relatively single, and there are a series of disadvantages: large volume and weight; insulating oil poses a threat to the environment; it cannot maintain output voltage stability and improve power quality.

[0004] At present, limited by the withstand voltage level of power semiconductor devices, single-stage power electronic transformers cannot meet the voltage level of the distribution network. This is a major factor that limits the practical application of power electronic transformers. Make up for the lack of single-stage type, but the series-parallel connection of modules will introduce the imbalance of voltage and power between modules, and even cause the entire power electronic transformer system to fail to work normally, so corresponding control methods must be adopted to ensure power and power. voltage balance

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