Global resonance inhibition device and method of multi grid-connected inverter system based on virtual impedance

Abstract

The invention relates to a global resonance inhibition device and method of a multi grid-connected inverter system based on the virtual impedance, and belongs to the field of power and electronics. An inverter is independently added and serves as a resonance inhibition unit to generate a virtual impedance unit, and the virtual impedance unit is connected in parallel to a coupling point PCC between the grid-connected inverters and the common electrical network. The method is characterized in that the frequency of a resonant point and the impedance of the frequency near the resonant point are very low, and the resonant point of the PCC point and voltage near the resonant point are reduced. The method can be used to effectively inhibit the resonance of the electrical network without influence on fundamental wave control of the grid-connected inverters.

Description

technical field [0001] The invention belongs to the field of power electronics, and in particular relates to a device and method for suppressing global resonance of a multi-grid-connected inverter system based on virtual impedance. Background technique [0002] Due to the global energy crisis and environmental pressure, new energy power generation has received more and more attention. In order to reduce the impact of new energy on the power grid, the concept of micro-grid has also been proposed, and has developed rapidly in recent years. The main interface between new energy and the microgrid is the grid-connected inverter. When a large number of grid-connected inverters are connected in parallel to the bus bar or common connection point of the microgrid, if the internal impedance of the grid is not zero, each inverter There will be interaction between them, which will lead to the decline of the output performance of the inverter, and in severe cases, the system will be uns...

AI Technical Summary

Problems solved by technology

The main interface between new energy and the microgrid is the grid-connected inverter. When a large number of grid-connected inverters are connected in parallel to the bus bar or common connection point of the microgrid, if the internal impedance of the grid is not zero, each inverter There will be interaction between them, resulting in the decline of the output performance of the inverter, and in severe cases, it will lead to system instability

Some scholars have found that the multi-grid inverter system based on the LCL filter has multiple resonance points due to the characteristics of the LCL filter itself and the interaction between the inverters. The safe and stable operation of microgrid poses a serious threat

However, most of the current research focuses on the resonance suppression measures of a single inverter, and there is still a lack of research on resonance suppression methods for multi-grid inverter systems.

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