A Modeling Method of Virtual Synchronous Machine Considering Excitation Circuit

Abstract

The invention relates to modeling technology and aims to provide a modeling method of a virtual synchronous machine considering an excitation circuit. Based on the three-phase bridge inverter topology, by ignoring the inner loop voltage and current loop in the control system, the power loop of the virtual synchronous machine is analyzed; the flux equation, voltage equation, torque equation, Power equation and motion equation, further ignoring the derivative term and zero sequence term in the model, a simplified motor model is proposed; in this model, the excitation current is virtualized by using the reactive power deviation value and the excitation coefficient, and the excitation circuit is constructed; the obtained The motor model is expressed in the form of small-signal disturbance, and a low-order small-signal model of the virtual synchronous machine considering the excitation circuit is obtained. The invention does not need to change the grid-connected topological structure of commonly used inverters, and can use mature and widely used ordinary grid-connected inverters for model research, and complete model testing without increasing additional hardware costs.

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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