基于虚拟同步机控制的单级式光伏并网系统强迫低频振荡分析  

Analysis of Forced Low-frequency Oscillation in Single-stage Grid-connected Photovoltaic System Based on Virtual Synchronous Generator Control

作　　者：龚振 沈汉铭 谢小荣[1,2] 张浙波 杨磊 步弋辰 GONG Zhen;SHEN Hanming;XIE Xiaorong;ZHANG Zhebo;YANG Lei;BU Yichen(Department of Electrical Engineering,Tsinghua University,Beijing 100084,China;State Key Laboratory of Power System Operation and Control(Tsinghua University),Beijing 100084,China;Zhejiang Provincial Energy Group Co.,Ltd.,Hangzhou 310007,China;Zhejiang Zheneng Technology Research Institute Co.,Ltd.,Hangzhou 310000,China;Zhejiang Zheneng Jiaxing Offshore Wind Power Co.,Ltd.,Zhejiang 314211,China)

机构地区：[1]清华大学电机工程与应用电子技术系,北京市100084 [2]新型电力系统运行与控制全国重点实验室(清华大学),北京市100084 [3]浙江省能源集团有限公司,浙江省杭州市310007 [4]浙江浙能技术研究院有限公司,浙江省杭州市310000 [5]浙江浙能嘉兴海上风力发电有限公司,浙江省嘉兴市314211

出　　处：《电力系统自动化》2024年第16期18-29,共12页Automation of Electric Power Systems

基　　金：国家自然科学基金资助项目(U22B20100);国家资助博士后研究人员计划资助项目(GZC20231212)。

摘　　要：光伏并网系统中,最大功率点跟踪(MPPT)控制会在直流侧电压中引入大量间谐波,可能引发强迫振荡。传统研究重点关注扰动源频率与系统固有弱阻尼模式频率的关系,较少关注变换器控制特征对加剧强迫振荡的效果。文中以虚拟同步机(VSG)控制为例,构建单级式光伏并网系统功率输入输出频域闭环传递函数模型,指出了MPPT控制引入的间谐波会导致基于VSG控制的单级式光伏并网系统发生强迫低频振荡。与基于传统二阶时域微分方程的强迫振荡分析方法进行对比,论证了所提闭环传递函数与传统二阶微分方程的等价性,从而便于从频域输入-输出关系角度更直观地分析扰动源和变换器控制特征对强迫振荡的影响。最后,分析了VSG超调效应和有功、无功功率动态耦合效应对强迫振荡的影响机理,并基于仿真算例验证了VSG控制超调和功率耦合对加剧强迫振荡的影响特性。In the grid-connected photovoltaic system,the maximum power point tracking(MPPT)control will introduce massive interharmonics to DC-side voltages,which may cause forced oscillations.Traditional research focuses on the relationship between the frequency of disturbance sources and the frequency of the inherent weak damping mode of the system,with less attention paid to the effect of converter control characteristics on exacerbating the forced oscillation.This paper takes the virtual synchronous generator(VSG)control as an example to construct a power input-output frequency-domain closed-loop transfer function model of the single-stage grid-connected photovoltaic system.It is pointed out that the interharmonics introduced by the MPPT control will cause forced low-frequency oscillation in the single-stage grid-connected photovoltaic system based on the VSG control.Then,the proposed model is compared with the the forced oscillation analysis method based on the traditional second-order time-domain differential equation.The equivalence between the proposed closed-loop transfer function and the traditional second-order differential equation is verified.Thus,the influence of disturbance sources and converter control characteristics on the forced oscillation can be analyzed from the perspective of the frequency-domain input-output relationship.Finally,the influence mechanisms of the VSG overshoot effect and dynamic coupling effect of active and reactive power on the forced oscillation are analyzed.The characteristics of the influence of the VSG control overshoot and power coupling on the exacerbation of forced oscillation are verified by simulation cases.

关 键 词：光伏并网系统 间谐波 强迫振荡 虚拟同步机 超调效应 功率耦合 

分 类 号：TM712[电气工程—电力系统及自动化] TM615TM341