Photovoltaic solid-state transformer, photovoltaic inverter system and bidirectional high-voltage current transformer

Abstract

The embodiment of the invention provides a photovoltaic solid-state voltage transformer, a photovoltaic inverter system and a bidirectional high-voltage current transformer. The photovoltaic solid-state voltage transformer comprises multiple single-phase modules and filters, wherein each of the single-phase modules comprises multiple multi-output isolation type DC/DC converters and multiple cascaded DC/AC modules; each of the multi-output isolation type DC/DC converters comprises a DC/AC module, a high-frequency voltage transformer, and an AC/DC module; specifically, input ends of the cascadedDC/AC modules are connected with an output end of at least one AC/DC module; output ends of the multiple cascaded DC/AC modules are cascaded; and the multiple single-phase modules and the filters arenetworked via a star connection method or a delta connection method. Therefore, according to the photovoltaic solid-state voltage transformer provided by the embodiment of the invention, the DC/DC converters and the cascaded DC/AC modules are adopted and both are simple logic switches, so the size is reduced; and moreover, the conversion efficiencies of the DC/DC converters and the cascaded DC/ACmodules are higher than 99%, so the working efficiency of the system is higher than 98.5%, and the overall efficiency of the solid-state voltage transformer is improved.

Description

technical field [0001] The invention relates to the technical field of new energy power generation, in particular to a photovoltaic solid-state transformer, a photovoltaic inverter system and a bidirectional high-voltage converter. Background technique [0002] Usually, in a conventional photovoltaic power generation inverter system, after the photovoltaic modules are connected in series to 1000V or 1500V, they are connected to a string inverter or a centralized inverter. Phase 315V, 360V, 400V, 550V, etc.), and connected to the power step-up transformer, the power step-up converter outputs 10KV, 22KV, 35KV, 110KV and then merges into the grid. [0003] In an actual photovoltaic power station, the inverter and the power step-up transformer are usually purchased from different manufacturers. In the field, there is a certain distance between the two, and they need to be connected on-site with cables. Due to the use of connecting cables, on the one hand, it brings hidden dang...

AI Technical Summary

Problems solved by technology

Due to the use of connecting cables, on the one hand, it brings hidden dangers of joint failures caused by irregular construction and quality problems of cable joints, and on the other hand, it brings a certain amount of power loss and increased costs.

[0004] Integrating the inverter with the power step-up transformer has become a development trend of the current photovoltaic power generation inverter system. However, the power step-up transformer works at power frequency and requires a large amount of materials such as copper and iron, which is relatively large.

In addition, there are also disadvantages such as high no-load loss, DC bias, harmonics generated when the iron core is saturated, excitation inrush current is generated when it is put into the grid, and the primary and secondary harmonics and faults are related to each other.

[0005] In addition, on the other hand, the structure of integrating the inverter and the power step-up transformer is replaced by a solid-state transformer. The solid-state transformer is based on components such as power semiconductors and capacitors and inductors, including AC / DC, isolated DC / DC and DC / AC three-stage, but the system efficiency of this structure is lower (assuming each stage is 99% efficient, then the three-stage system efficiency is lower than 97%)

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