Topological structure of photovoltaic inverter with wide input and middle-high voltage alternating current output

Abstract

The invention relates to a topological structure of a photovoltaic inverter with wide input and middle-high voltage alternating current output. The invention relates to the technical field of a power system, a high-voltage power grid and a photovoltaic power generation system, the structure comprises a photovoltaic string, a multi-path LLC resonant multi-level half-bridge circuit and a multi-cascade H-bridge half-bridge multi-level circuit, the photovoltaic string is connected with the multi-path LLC resonant multi-level half-bridge circuit, and the multi-cascade H-bridge half-bridge multi-level circuit is connected with the multi-cascade H-bridge half-bridge multi-level circuit. The multi-path LLC resonant multi-level half-bridge circuit is connected with the multi-cascade H-bridge half-bridge multi-level circuit, and the multi-cascade H-bridge half-bridge multi-level circuit is respectively connected with an A phase, a B phase and a C phase. Under the limiting condition of the voltage class of an existing power device, the voltage class of direct-current input and alternating-current output of the photovoltaic inverter can be improved, the power loss on a circuit and a cable line is reduced, and the power generation efficiency of a whole set of photovoltaic system is improved; the number of power devices in the circuit is reduced by half, and the input cost of the power devices of the photovoltaic inverter is reduced.

Description

technical field [0001] The invention relates to the technical field of power systems, medium and high voltage power grids, and photovoltaic power generation systems, and relates to a topological structure of a photovoltaic inverter with wide input and medium and high voltage AC output. Background technique [0002] With my country's increasing emphasis on carbon emissions, renewable energy power generation accounts for an increasing share of my country's annual new power generation. As a kind of renewable energy, solar energy has the advantages of abundant reserves, inexhaustibility, inexhaustibility, and no geographical restrictions. It is generally considered to be a new energy that can effectively replace conventional fossil energy in the future. At present, reducing the initial investment cost of photovoltaic power generation system and improving the operating efficiency of photovoltaic power generation system are important research directions in the field of solar power...

AI Technical Summary

Problems solved by technology

However, although the single-phase H-type full-bridge circuit has a simple structure, it uses more power devices, which increases the input cost of the photovoltaic power generation system in disguise and affects the application of the cascaded circuit topology in the photovoltaic power generation system.

[0005] In addition, the cascade connection of single-phase H-type full-bridge circuits is used to increase the output voltage level of the inverter. Although the circuit structure is simple and the control is relatively easy, it is difficult to maintain the same power generation between each photovoltaic string, resulting in The power generated by each phase of the photovoltaic inverter is different, so it is easy to generate circulating current inside the photovoltaic inverter, which affects the operating efficiency and stability of the photovoltaic inverter

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