Modeling method of virtual synchronous generator taking excitation circuit into consideration

Abstract

The invention relates to the modeling technology, and aims to provide a modeling method of a virtual synchronous generator taking an excitation circuit into consideration. Based on a three-phase bridge inverter topological structure, a power loop of the virtual synchronous generator is analyzed by neglecting an inner ring voltage and a current loop in a control system; by referring to a flux linkage equation, a voltage equation, a torque equation, a power equation and a motion equation of a traditional synchronous machine, a simplified motor model is proposed by further neglecting a derivativeterm and a zero sequence term in the model; in the model, the excitation current is calculated in a virtual mode by utilizing a reactive power deviation value and an excitation coefficient, and an excitation circuit is constructed; and the obtained motor model is expressed in a small signal disturbance mode, so that a low-order small signal model of the virtual synchronous generator taking the excitation circuit into consideration is obtained. According to the method, the grid-connected topological structure of the common inverter does not need to be changed, and a common grid-connected inverter which is mature and wide in application can be used for carrying out model research, so that the model test is completed under the condition that additional hardware cost is not increased.

Description

technical field [0001] The invention relates to modeling technology, in particular to a modeling method of a virtual synchronous machine considering an excitation circuit. Background technique [0002] New energy technology has huge economic benefits and is part of the national development strategy. The traditional inverter tracks the grid voltage phase through a phase-locked loop (PLL), and controls the inverter output voltage or current to follow the grid voltage phase obtained by the phase-locked loop, which can be considered as a grid-following control method. This control method can operate effectively in the grid with large system capacity and strong stability. However, as new energy sources such as photovoltaics and wind energy are fed into the grid, some traditional sources of electric energy, such as thermal power plants, are squeezed out of the grid, and the system inertia and damping ratio are relatively reduced, and the system stability is seriously threatened. ...

AI Technical Summary

Problems solved by technology

Power electronic equipment is often limited by hardware. Taking these constraints into consideration, such as the energy storage capacity of the DC side, the configuration of the moment of inertia and damping coefficient is undoubtedly based on the difficulty, but it is also closer to the actual problem.

[0005] However, insufficient attention has been paid to the analysis of reactive power loops

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