基于自适应指数函数的变参数VSG控制

Variable parameter VSG control based on adaptive exponential function

近年来,随着电网的电力电子化程度升高,电网的整体惯量减小,电虚拟同步机(VSG)技术应运而生并迅速发展。其核心思想是模仿传统能源所应用到的同步发电机的电气特性和机械特性,提高高比例分布式能源系统的转动惯量。然而,现有VSG控制策略的控制参数固定或者简单连续变化,针对小扰动可能会引起系统功率的振荡等问题。为更加灵活调整虚拟惯量和阻尼系数,在详细分析VSG基础上,提出一种基于分段指数函数的变参数VSG自适应控制策略,其虚拟惯量和旋转阻尼随电网频率的变化按照指数函数轨迹变化,从而达到减小电网波动的目的,并且扰动变化率较小时参数变化较小,避免引起系统振荡问题;最后设计主电路部分和VSG控制部分的参数,并通过仿真证明了该策略能有效改善逆变器工作的稳定性。

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.