摘要
基于模块化多电平矩阵变换器(M3C)的低频输电系统(LFTS)在海上风电送出、城市电网及远距离输电相关领域应用潜力巨大。为研究LFTS启动过程及相关控制策略,实现M3C在无电压电流冲击状态下将换流站连接到低频输电线路,文中提出一种无扰动并网的启动方法。首先,分析LFTS结构及工作原理。然后,以双端LFTS为对象,分析M3C子模块选取原则以及充电过程。利用电容处于额定电压时闭锁M3C不与低频电网交换功率的特性,通过灵活控制M3C以及合理设计启动逻辑,无须新增检同期装置及控制算法,可解决LFTS启动时易出现的过压过流问题。最后,搭建实时数字仿真系统(RTDS)进行验证,仿真结果表明了所提控制策略的正确性,各换流站连接到低频输电线路时无电压电流冲击,工程应用前景较好。
Low-frequency transmission system(LFTS)based on modular multilevel matrix converter(M3C)has great application potential in offshore wind power transmission,urban power grid and long-distance power transmission.In order to study the startup process and the control strategies of LFTS and connect the converter station to the low-frequency transmission line without voltage or current impulse of M3C,a startup method of undisturbed grid connection is proposed.Firstly,the structure and operating principle of the LFTS are analyzed.Then,the selection principle of sub modules and the charging process of M3C are analyzed with two-terminal LFTS as the target.Taking the advantage that the blocked M3C does not exchange power with the low-frequency power grid when the capacitor is at rated voltage,the problems of over-voltage and over-current that tend to occur during LFTS startup can be solved by flexible control of M3C and reasonable design of startup strategy,without additional control devices and detecting the synchronization of the breaker.Finally,a real time digital simulation system(RTDS)is built to verify the proposed startup method.The simulation results show that converter stations connect to the low-frequency transmission line without voltage or current impulse.Also,the proposed strategy is correct and has a great prospect of the engineering application.
作者
陆立文
吴小丹
周前
董云龙
邱德锋
潘磊
LU Liwen;WU Xiaodan;ZHOU Qian;DONG Yunlong;QIU Defeng;PAN Lei(NR Electric Co.,Ltd.,Nanjing 211102,China;State Grid Jiangsu Electric Power Co.,Ltd.Research Institute,Nanjing 211103,China)
出处
《电力工程技术》
北大核心
2022年第5期31-39,共9页
Electric Power Engineering Technology
基金
国家电网有限公司总部科技项目“岸-场协同动态低频海上风电系统研究”(4000-202218073A-1-1-ZN)。
关键词
低频输电
模块化多电平矩阵变换器(M3C)
临时闭锁
无同期
无电压电流冲击
并网控制
low-frequency transmission
modular multilevel matrix converter(M3C)
temporary blocking
without the synchronization
without voltage or current impulse
grid connection control
