锁相环同步VSC接入弱网下的低频动态稳定性分析模型与机理研究  

Low frequency dynamic stability analysis model and mechanism research for PLL-synchronized VSC connected to weak grid

作　　者：李霞林[1] 张晨[1] 郭力[1] 张野 高飞[3] 王智[1] 李鹏飞[1] 王成山[1] LI Xialin;ZHANG Chen;GUO Li;ZHANG Ye;GAO Fei;WANG Zhi;LI Pengfei;WANG Chengshan(Key Laboratory of Smart Grid of Ministry of Education,Tianjin University,Tianjin 300072,China;State Key Laboratory of HVDC,Electric Power Research Institute,China Southern Power Grid,Guangzhou 510663,China;Key Laboratory of Power Transmission and Power Conversion Control of Ministry of Education,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]天津大学智能电网教育部重点实验室,天津300072 [2]南方电网科学研究院有限责任公司直流输电技术国家重点实验室,广东广州510663 [3]上海交通大学电力传输与功率变换控制教育部重点实验室,上海200240

出　　处：《电力自动化设备》2022年第8期29-38,54,共11页Electric Power Automation Equipment

基　　金：国家自然科学基金资助项目(51977142);国家重点研发计划资助项目(2020YFB1506803)。

摘　　要：基于锁相环(PLL)同步接入弱网的电压源型换流器(WG-VSC)存在由“外环-PLL-弱网”交互主导的低频动态(LFD)稳定问题。为清晰揭示各关键环节及其交互对WG-VSC的LFD影响机理,提出一种等效PLL模型。首先建立了适用于多种典型外环控制模式的WG-VSC的LFD分析的基本模型,该模型包含原PLL环节及耦合了外环、电网强度及VSC运行点信息的“外环-弱网”环节。其次,将“外环-弱网”环节划分为有功侧外环对PLL的影响路径及无功侧外环所引入的对PLL的影响路径,以清晰表征VSC外环与PLL的交互关系。然后,基于LFD主导模态将“外环-弱网”环节简化为一阶环节,并结合原PLL的PI控制环节,得到保持足够LFD分析精度的二阶等效PLL模型,并基于该模型分析和揭示了“外环-PLL-弱网”的交互对WG-VSC的LFD的影响机理。最后,基于详细开关模型的时域仿真结果验证了等效PLL模型的有效性和分析结果的准确性。The LFD(Low Frequency Dynamic)stability problem of WG-VSC(Weak Grid connected Voltage Source Converter)based on PLL-synchronized is dominated by“outer loop-PLL-weak grid”interaction.To reveal the influence mechanism of key loops and their interactions on LFD of WG-VSC,a PLL-equivalent model is proposed.Firstly,the basic LFD analysis model suitable for many typical outer loop control modes is put forward,which contains original PLL loop and“outer loop-weak grid”loop coupled with outer loop,grid strength and information of VSC operation point.Secondly,the“outer loop-weak grid”loop is divided into two parallel paths,one of which shows the impact of active-side outer loop on PLL,and the other shows the additional influence on PLL induced by reactive-side outer loop.Thirdly,the“outer loop-weak grid”loop is simplified into a first-order loop based on dominant modes of LFD,and the second-order PLLequivalent model that can maintain sufficient accuracy for LFD analysis is derived combined with the PI control loop of original PLL.Based on the above model,the influence mechanism of“outer loop-PLL-weak grid”interaction on LFD of WG-VSC is analyzed and revealed.Finally,the effectiveness of PLL-equivalent model and the accuracy of analysis results are verified by the time-domain simulative results based on detail switch model.

关 键 词：电压源型换流器 低频动态 弱网 等效锁相环模型 控制环节交互 机理分析 

分 类 号：TM712[电气工程—电力系统及自动化]