虚拟同步机控制模块化多电平变流器阻抗建模及次/超同步振荡稳定性分析  

Impedance Modeling and Sub/Super Synchronous Oscillation Stability Analysis of Modular Multilevel Converter under Virtual Synchronous Generator Control

作　　者：高本锋 沈雨思 宋瑞华 杨大业 张建坡 李刚 Gao Benfeng;Shen Yusi;Song Ruihua;Yang Daye;Zhang Jianpo;Li Gang(Hebei Key Laboratory of Distributed Energy Storage and Micro-Grid North China Electric Power University,Baoding 071003,China;China Electric Power Research Institute,Beijing 100192,China)

机构地区：[1]河北省分布式储能与微网重点实验室(华北电力大学),保定071003 [2]中国电力科学研究院有限公司,北京100192

出　　处：《电工技术学报》2025年第2期559-573,共15页Transactions of China Electrotechnical Society

基　　金：国家电网公司科技资助项目“大规模新能源送出系统宽频振荡电磁暂态仿真评估及抑制技术研究”(5108-202218280A-2-275-XG)。

摘　　要：虚拟同步机控制已广泛应用于新型电力系统中,然而其研究主要集中于新能源领域,对于柔性直流输电领域中出现的次/超同步振荡、并网稳定性等问题仍有待研究。该文针对虚拟同步机控制的模块化多电平变流器(MMC),采用谐波线性化的方法建立其序阻抗模型,探究各控制参数对其阻抗特性的影响。同时,对比分析跟网型、构网型MMC的阻抗特性及其并网稳定性,并提出虚拟阻抗控制优化方案以提高构网型MMC系统阻尼。结果表明,构网型MMC具有良好的弱电网稳定性,但在强电网下存在次/超同步振荡的风险,在控制回路中加入虚拟阻抗控制可以增加变流器等效输出阻抗,从而增强MMC并网系统的稳定性。同时,无功下垂和电压外环环节在构网型MMC的阻抗特性中起决定性作用,适当增大无功下垂系数和电压外环积分系数,有利于减小阻抗负阻尼区间,从而提高并网系统稳定性。Virtual synchronous generator(VSG)control has been widely used in new power systems.Its research mainly focuseson new energy,and the problems of sub/supersynchronous oscillation and grid-connected stability in the VSC-HVDC still need to be clarified.Limitations exist in the research on the impedance modeling of grid-forming modular multilevel converter(MMC)and the sub/supersynchronous stability problem.The characteristics of the sub/supersynchronous oscillation mechanism in real projects of grid-forming MMC cannot be characterized,and the oscillation suppression method is also immature.Therefore,it is essential to conduct sequence impedance modeling,grid-connected system stability analysis and control optimization for grid-forming MMC.This paper adopts the harmonic linearization method to establish the sequence impedance model of grid-constructed MMC and verifies the accuracy of the analytical model by frequency scanning.Secondly,the impedance characteristics and grid-connected stability are compared with the traditional grid-following MMC.Then,the control optimization design scheme based on virtual impedance is adopted to optimize the impedance characteristics of the grid-forming MMC and improve the stability of the grid-connected system.Finally,the effects of active control,reactive control,voltage outer loop,and current inner loop parameters on the impedance characteristics of grid-forming MMC areexplored.Results show that grid-forming MMC has better stability in weak grids.However,there is a risk of sub/supersynchronous oscillation in strong grids,and virtual impedance control can increase the equivalent output impedance of the converter,thereby enhancing the stability of the MMC grid-connected system.At the same time,the reactive power droop and voltage outer loop link play a decisive role in the impedance The following conclusions can be drawn.(1)In the network construction MMC sequence impedance modeling,the small signal of the reference phase angle generated by VSG control has little influence on the impe

关 键 词：虚拟同步机控制 模块化多电平变流器(MMC) 序阻抗建模 次/超同步振荡 稳定性分析 虚拟阻抗 

分 类 号：TM712[电气工程—电力系统及自动化]