基于VSG的低压柔性直流系统连接串联补偿电网的稳定性分析  

Stability Analysis of VSG-Based Low Voltage Flexible DC System Connected to Series Compensation Grid

作　　者：李颖 鲍一鸣 田雨 杨永祥 刘建华 吕波 唐乾 LI Ying;BAO Yiming;TIAN Yu;YANG Yongxiang;LIU Jianhua;LÜBo;TANG Qian(Liupanshui Power Supply Bureau,Guizhou Power Grid Co.,Ltd.,Liupanshui 553002,Guizhou,China;School of Electrical Engineering,Shanghai University of Electric Power,Shanghai 200090,China)

机构地区：[1]贵州电网有限责任公司六盘水供电局,贵州六盘水553002 [2]上海电力大学电气工程学院,上海200090

出　　处：《电网与清洁能源》2022年第10期51-59,68,共10页Power System and Clean Energy

基　　金：国家自然科学基金(51207086);贵州电力公司科技项目(060200KK52200010)。

摘　　要：低压柔性直流输电系统可实现异步电网互联,并且具有控制灵活等优点。而虚拟同步机技术通过模拟传统同步发电机的外特性可以弥补电力电子设备无惯性和阻尼的缺点。然而,虚拟同步机与串联补偿电网之间的阻抗交互作用可能导致系统失稳,而目前这方面的研究较少。该文对基于虚拟同步机的低压柔性直流输电系统进行序阻抗建模,通过伯德图分析低压柔直虚拟同步机连接串联电容补偿电网的稳定性。提出一种动态虚拟阻尼系数的有源阻尼控制方法,通过动态调节虚拟同步机阻尼系数,同时结合调制信号反馈有源阻尼方法,共同抑制次同步振荡。所提出的改进后的有源阻尼控制方法可以解决调制信号反馈有源阻尼方法中,虚拟电阻值设置过大造成的工作点偏移。最后通过Simulink仿真验证所提出方法的有效性。The low-voltage flexible DC transmission system can realize asynchronous power grid interconnection and has the advantages of flexible control. The virtual synchronous machine technology can make up for the disadvantage of power electronic equipment without inertia and damping by simulating the external characteristics of traditional synchronous generators. However,the impedance interaction between virtual synchronous machine and series compensation power grid may lead to system instability,and there is little research in this field at present. In this paper,the sequence impedance model of low-voltage flexible DC transmission system based on virtual synchronous machine is established,and the stability of low-voltage flexible DC virtual synchronous machine connected with series capacitor compensation grid is analyzed by Bode diagram. An active damping control method with dynamic virtual damping coefficient is proposed. By dynamically adjusting the damping coefficient of virtual synchronous machine,combined with the modulation signal feedback active damping method,the subsynchronous oscillation is suppressed. The improved active damping control method can solve the working point offset caused by the excessive setting of virtual resistance in the modulation signal feedback active damping method. Finally,the effectiveness of the proposed method is verified by Simulink simulation.

关 键 词：低压柔性直流输电 虚拟同步机 串联补偿电网 次同步振荡 

分 类 号：TM76[电气工程—电力系统及自动化]