A power electronic transformer with an energy storage device

Abstract

The invention discloses a power electronic transformer with an energy storage device and relates to the technical field of electric engineering. The power electronic transformer includes a power electronic transformer with high voltage side connected to 10kV distribution network, A low-voltage side of the power electronic transformer is connected with a 400V class distribution network, and a three-phase 10kV alternating voltage is divided and isolate through a A-phase circuit, a B-phase circuit and a C-phase circuit, and the high-voltage alternating current is converted into direct current, all of which are connected with DC buses P and N, and the DC buses P and N are electrically connected with energy storage type Quasi-Z-source inverter converts DC to three-phase 400V AC to low-voltage distribution network. The power electronic transformer reduces the number of high-frequency transformers and sub-modules, The power density of the power electronic transformer is increased, and the harmonics brought by the power electronic transformer to the upper distribution network can be effectively restrained. Under the condition of ensuring the power quality, the low-voltage distribution network can be kept stable, and the voltage / frequency regulation of the upper distribution network can be participated in, and the power electronic transformer has certain inertia and damping.

Description

technical field [0001] The invention relates to the technical field of electrical engineering, in particular to a power electronic transformer with an energy storage device. Background technique [0002] A power electronic transformer is a transformer that combines power electronic devices and high-frequency transformers to realize power conversion through power electronic conversion technology. In addition to basic functions such as voltage conversion, electrical isolation, and energy transfer, it also has high controllability It can realize the advantages of waveform, power flow, power quality control and automatic protection control, and is an ideal distribution equipment for distribution network. It has been widely used in on-board converter systems for electric locomotive traction, smart grid / energy internet and distributed renewable energy generation grid-connected systems. [0003] Conventional inverters are used at the output end of conventional power electronic tra...

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Problems solved by technology

[0003] Conventional power electronic transformers use conventional inverters at the output end. In order to prevent damage to the inverter due to simultaneous conduction of the upper and lower switching tubes of the same inverter bridge arm, a dead time is often added to the switching signal of the bridge arm switching tube, which instead makes the output The AC voltage waveform is distorted

In addition, the topology does not have a modular structure, and as the number of levels increases, the circuit topology becomes extremely complex, so a power electronic transformer with energy storage device is needed

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