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Keywords

virtual synchronizer control; three‑level inverter; distributed energy; variable virtual inertia; variable damping coefficient

Abstract

In recent years, with the increasing electronization of the power grid, the overall inertia of the grid has decreased. As a result, the technology of virtual synchronous generator (VSG) has emerged and rapidly developed. The core idea is to mimic the electrical and mechanical characteristics of synchronous generators used in traditional power systems in order to enhance the rotational inertia of high‑proportion distributed energy systems. However, the existing control strategies for VSG have fixed control parameters or simple continuous variations, which may lead to power oscillations in the system when subjected to small disturbances. In order to adjust the virtual inertia and damping coefficient more flexibly, a variable‑parameter VSG adaptive control strategy based on piecewise exponential functions is proposed after a detailed analysis of VSG. The variation of virtual inertia and rotational damping with grid frequency follows an exponential function trajectory, aiming to reduce grid fluctuations. Additionally, when the disturbance rate is low, the parameter changes are small to avoid causing system oscillations. Finally, the parameters of the main circuit and the VSG control part are designed, and simulation results show that the strategy can effectively improve the stability of the inverter operation.

DOI

10.19781/j.issn.1673-9140.2023.03.013

First Page

124

Last Page

131

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