Three-level photovoltaic grid-connected inversion technology

Abstract

The invention relates to the research of three-level photovoltaic grid-connected inversion technology, and belongs to the novel field of photovoltaic power generation. A whole photovoltaic power generation system mainly comprises two parts including a main circuit and a control circuit, wherein the main circuit mainly also comprises two parts, i.e. a DC conversion part and a grid-connected inversion part, the DC conversion part relates to a solar battery maximum power point track and a DC voltage booster circuit, and the grid-connected inversion part relates to the problem that the inversion of the DC and the output AC subjected to inversion are required to be same with a power grid voltage in the frequency and phase, as well as the isolated island grid-connected problem. The control circuit is a necessary part of the whole system, and comprises a drive circuit, a current and voltage acquisition circuit, an isolated island detection circuit and corresponding software control algorithm design and the like of a power device. The system adopts a three-level inverter and intelligent control algorithm, so as to effectively overcome the defects of the conventional inverter of high consumption and low efficiency, improve energy utilization ratio and electric energy quality under the new situation; and besides, output wave shape on the inverter network side is more close to the sine wave, so that high voltage and larger power output is easily achieved.

Description

technical field [0001] The invention relates to the field of electric new energy, in particular to three-level photovoltaic grid-connected inverter technology. Background technique [0002] The whole world is advocating and vigorously promoting the development and utilization of new energy. Solar energy is an emerging renewable energy source. This is a promising new type of power supply, which has three significant advantages of permanence, cleanliness and flexibility. Solar photovoltaic power generation is the conversion of solar energy into electrical energy, which has the advantages of no noise, no pollution, safety and reliability, low failure rate, less constraints, and convenient maintenance. [0003] At present, most solar power generation systems include: solar photovoltaic array - DC conversion circuit (maximum power point tracking) - traditional two-level inverter - island detection and grid connection. The system uses a traditional two-level inverter, which has...

AI Technical Summary

Problems solved by technology

The system uses a traditional two-level inverter, which has inherent shortcomings such as large voltage stress (du / dt), large electromagnetic interference (EMI), high switching frequency, and large loss. The efficiency is low, and it has certain harmonics. The biggest weakness is that it is not suitable to achieve high voltage and high power output due to the limitation of the power and withstand voltage of the switch tube.

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