Cascading modularized multi-level dynamic switching DC-DC transformer

Abstract

The invention discloses a cascading modularized multi-level dynamic switching DC-DC transformer. The transformer includes two parts comprising a transformer A and a transformer B. A voltage stabilizing capacitor C is mounted in a cascading part between the transformer A and the transformer B. Each of the transformer A and the transformer B includes a group of five voltage transformation sub modules connected in series and the ratios of transformation are set to be k1 and k2 respectively. When the two stages of the transformers are equipped with NSUM1 transformation sub modules and NSUM2 transformation sub modules respectively, the transformation effect is equal to that of a single transformer equipped with the transformation sub modules of a quantity of NSUM1* NSUM2. Compared with prior art, by the aid of transformer cascading connection, the number of the sub modules is reduced substantially, an AC transformer is not required and the economical efficiency advantage is distinct. At thesame time, since the number of capacitor is reduced substantially, the size of the DC transformer can be reduced effectively, so that promotion and application are facilitated. Adjustment of the ratio of transmission can be realized through dynamic adjustment of the ratios of transformation of the cascaded transformers.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a cascaded modular multilevel dynamic switching DC-DC transformer. Background technique [0002] Renewable energy has the characteristics of volatility and intermittency. The large-scale connection of new energy sources such as wind energy and photovoltaics to the power grid will have a profound impact on the safe and stable operation of the AC power grid. The rapid development of flexible DC transmission technology has provided effective solutions for the realization of large-scale centralized access of wind energy and photovoltaic power generation, grid interconnection, and power supply in cities and islands. However, there are still some problems in flexible DC transmission technology that need to be solved urgently. [0003] Similar to the AC transformer in the AC grid, the DC-DC transformer is the key equipment to realize DC multi-voltage level conversion and DC power flow...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the DC voltage level transformation that needs to be solved in the current flexible DC system, taking into account the equipment volume and economy, the present invention proposes a cascaded modular multi-level dynamic switching DC-DC transformer, aiming at the DC voltage level that needs to be solved urgently in the DC grid Transformation function, consider equipment size and economy to design a DC transformer with dynamic switching of cascaded sub-modules

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