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.
作者
李霞林
张晨
郭力
张野
高飞
王智
李鹏飞
王成山
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)
出处
《电力自动化设备》
EI
CSCD
北大核心
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)。
