Novel DC power electronic transformer topology having automatic fault removal capability

Abstract

The invention proposes a novel DC power electronic transformer topology having automatic fault removal capability. A DC power electronic transformer is mainly applicable to the following occasions, ina first occasion, voltage conversion between a medium- and high-voltage DC bus and a low-voltage DC bus is performed, and in a second occasion, voltage conversion between different medium- and high-voltage buses is performed. With the novel DC power electronic transformer topology structure proposed by the invention, the numbers of cascaded DC / DC converters are reduced under the condition that the voltage stress of a switch device is enabled not to be changed, the numbers of transformers and switch devices are reduced, so that the volume and the weight of the DC power electronic transformer are further reduced; with the novel DC power electronic transformer topology structure proposed by the invention, soft switch can be achieved, the DC conversion efficiency is improved; and with the novel DC power electronic transformer topology structure proposed by the invention, automatic fault removal of a unit module can be achieved, and a DC contactor is not needed to removal a fault from a fault unit module.

Description

technical field [0001] The invention relates to a new power electronic transformer topology with fault self-cutting ability, which is suitable for flexible AC and DC transmission and distribution networks, new rail transit converters, new energy grid connection, energy Internet, etc. The field of high-voltage bidirectional isolated DC conversion. Background technique [0002] Power Electronic Transformer (PET) is a power conversion device based on power electronic conversion technology, equipped with high-frequency links, and capable of realizing voltage conversion, current conversion and electrical isolation. It is also often called a solid state transformer (Solid state transformer, SST). Power electronic transformers not only have the basic functions of traditional transformers, but also have the following characteristics: 1. Using medium and high frequency transformers instead of power frequency transformers reduces the volume and weight of transformers; 2. The voltage ...

AI Technical Summary

Problems solved by technology

There are three problems with the bypass contactor: first, the high-capacity high-voltage contactor is relatively large and occupies the volume of the equipment; second, for the existing cascaded circuit, regardless of AC or DC, the actual operation needs to consider "blocking the IGBT device". The sequence of "pulse" and "enable bypass contactor", because there is a delay in the response of the contactor, if the operation sequence is improper, it will cause the fault to spread and stop the entire system; thirdly, the bypass contactor cannot be directly connected to the The capacitors are connected in parallel, otherwise, the capacitor will be short-circuited by the contactor when the contactor operates, which will cause the contactor or capacitor to burn out

Therefore, the solution of using DC contactor will greatly increase the complexity, volume, weight and cost of the system

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