基于局部复阻抗模型的LCL型并网变换器相位重塑控制策略  

Phase Reshaping Control Strategy of LCL Grid Connected Converter Based on Local Complex Impedance Model

作　　者：王祺[1] 秦文萍[1] 张宇[1] 任春光[1] 王磊[1] 韩肖清[1] 王鹏[1] WANG Qi;QIN Wenping;ZHANG Yu;REN Chunguang;WANG Lei;HAN Xiaoqing;WANG Peng(Shanxi Key Laboratory of Power System Operation and Control(Taiyuan University of Technology),Taiyuan 030024,Shanxi Province,China)

机构地区：[1]电力系统运行与控制山西省重点实验室(太原理工大学),山西省太原市030024

出　　处：《中国电机工程学报》2021年第13期4415-4424,共10页Proceedings of the CSEE

基　　金：国家重点研发计划项目(2018YFB0904700);山西省重大专项项目(20181102028)。

摘　　要：LCL型并网变换器采用变换器侧电流闭环反馈方式会导致并网电流的相位滞后于并网电压,无法满足并网系统单位功率因数运行。由于该相位差较小,未得到重视。然而,随着新能源并网功率的大规模化、含无功元件变换器拓扑的复杂化,并网点的相位滞后问题将日益突出,严重时将导致电网有功功率缺额甚至电网解列。针对上述问题,该文定义了局部复阻抗的概念,分析了并网点相位差产生的原因,进而提出一种改善并网电流相位滞后的相位重塑策略。从阻抗角度厘清了被控电流与并网电流的相位空间矢量关系,在保留变换器侧电流闭环控制自稳性优点的同时,校正了并网电流与电压的相位差。该方法无需额外传感器,且无需重新设计锁相环,在电网畸变工况时仍有良好的适应性。所提局部复阻抗的概念可推广至其他LCL型滤波结构的变型及其派生拓扑的研究领域中,对改善并网功率因数的相关研究提供一定的借鉴意义。最后,仿真和实验案例验证了文中的分析结果的正确性和可行性。The LCL type grid connected converter adopts the closed-loop feedback mode of converter side current, which will lead to the grid connected current phase lagging behind the grid connected voltage, and can not meet the operation of grid connected system unit power factor. Due to the small phase difference, it has not been paid attention to in the related research fields. However, with the large-scale grid connected power of new energy and the complexity of converter topology with reactive components, the phase lag problem of parallel nodes will become increasingly prominent, which will lead to the lack of active power and even grid disconnection. To solve these problems, this paper defined the concept of local complex impedance, analyzed the causes of the phase difference of parallel nodes, and then proposed a phase reconstruction strategy to improve the phase lag of grid current. The phase space vector relationship between the controlled current and the grid connected current was clarified from the impedance point of view. The phase difference between the grid connected current and the voltage was corrected while maintaining the self stability of the converter side current closed-loop control. This method does not need additional sensors, and does not need to redesign the phase-locked loop. It still has good adaptability in the case of grid distortion. The concept of local complex impedance can be extended to other research fields of LCL type filter structure and its derived topology, which can provide some reference for improving the related research of grid connected power factor. Finally, the simulation and experimental cases verify the correctness and feasibility of the analysis results.

关 键 词：LCL变换器 并网电流 并网电压 相位重塑 局部复阻抗 

分 类 号：TM46[电气工程—电器]