Inverter system based on improved power distribution policy of virtual synchronous generator

Abstract

The invention discloses an inverter system based on the improved power distribution policy of a virtual synchronous generator. The inverter system comprises a grid-connected inverter system which is controlled by a virtual synchronous generator and is composed of a direct current voltage source, a three-phase bridge inverter circuit, an LCL filter, a public power grid, a load and a control drive circuit. The inverter system consists of an active regulator, an excitation regulator, a VSG algorithm module, and a voltage and current double closed-loop control module. The introduction of the control of the synchronous generator overcomes the problems of fast response and low inertia of a traditional grid-connected inverter. The permeability of renewable energy in a micro grid can be effectively improved. The dynamic characteristic of a synchronous generator rotor is introduced into a second-order transient model, which eliminates the influence of a traditional constant damping coefficienton droop control. In addition, by improving the reactive-voltage droop control, the influence of the inverter output filter impedance and the line impedance on reactive power distribution is reduced,and reasonable distribution of the inverter output power is ensured.

Description

technical field [0001] The invention relates to the field of micro-grid inverters, in particular to an inverter system based on a virtual synchronous generator to improve power distribution strategies. Background technique [0002] In recent years, the problems of environmental pollution and greenhouse effect have become increasingly prominent. Distributed renewable energy such as photovoltaics, wind energy, and fuel cells has become a powerful guarantee for governments and researchers to deal with this problem. As the interface between distributed energy and the AC grid, the power electronic converter is the core device of the microgrid, but it has no rotating parts, fast response and lack of inertia, resulting in rapid changes in the frequency and voltage of the microgrid under large disturbances. The virtual synchronous generator (VSG) control strategy enables the inverter to have frequency and voltage regulation characteristics by simulating the active power regulator a...

AI Technical Summary

Problems solved by technology

The location of distributed power sources in the microgrid is different, resulting in different equivalent transmission line impedances; in addition, due to the different operating conditions and design considerations of the microgrid system, the design of the output LCL filter of each distributed power supply will also be different. The equivalent output filter impedance of each inverter is not equal

The inequalities of these output impedances will directly affect the reactive power distribution based on droop control, and because the equivalent output impedance in low-voltage microgrids is generally resistive or resistive inductive, the inverter power regulation based on droop control will produce certain coupling, which affects the dynamic performance of the system

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