Dual-mode combination control method for multi-inverter system based on double-split transformer

Abstract

The invention discloses a dual-mode combined control method for a multi-inverter system based on a double-split transformer, and belongs to the field of electrical engineering. The present invention proposes a dual-mode combined control method for a multi-inverter system based on a double-split transformer for an extremely weak power grid. The equivalent grid impedance of the public coupling point of the transformer, and gradually increases according to the equivalent grid impedance, the system runs in the full current source mode, the mixed mode and the full voltage source mode in turn, thereby effectively improving the multi-inverter based on the double-split transformer. The stability of the system in the case of changes in the strength of the power grid. The invention is not only simple to implement, but also greatly increases the stability margin of the multi-inverter system based on double-split transformers when the grid impedance fluctuates greatly, especially ensures that the system can still operate stably under extremely weak grids, and improves the grid adaptability of the system sex.

Description

technical field [0001] The invention relates to a control method for a multi-inverter system based on a double-split transformer, in particular to a dual-mode combined control method for a multi-inverter system based on a double-split transformer, and belongs to the field of electrical engineering. Background technique [0002] At present, the development and use of renewable new energy such as wind energy and solar energy has been continuously increasing around the world. In particular, China, the United States and India have built and put into operation large-scale desert photovoltaic power plants above MW level, and the penetration rate of new energy power generation is getting higher and higher. . Moreover, for desert power stations with open sites, the structure of the centralized photovoltaic power generation system has the characteristics of simplicity, high efficiency, and easy maintenance, and has been widely used. In addition, the connection between photovoltaic g...

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Problems solved by technology

[0017] In order to overcome the limitations of the above-mentioned various technical solutions, the present invention aims at the stability problem when the multi-inverter system based on the double-split transformer adopts the traditional single current source mode or mixed mode under the extremely weak power grid, and proposes a double-split transformer-based The dual-mode combination control method of multi-inverter system, this method obtains the equivalent grid impedance of a grid-connected inverter common coupling point in the multi-inverter system based on double-split transformers through the grid impedance identification algorithm, when the equivalent The grid impedance gradually increases, that is, when the grid operates in strong grid, weak grid and extremely weak grid respectively, the system operates in full current source mode, hybrid mode and full voltage source mode in turn, thus effectively improving the multi-inverter based on double-split transformers. The stability of the inverter system in the case of changes in the strength of the power grid

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