弱电网下具有新型PLL结构的并网逆变器阻抗相位重塑控制  

Grid-connected Inverter Impedance Phase Reshaping Control With Novel PLL Structure in Weak Grid

作　　者：高家元 肖凡[1] 姜飞[2] 郭祺[1] 卢柏桦 GAO Jiayuan;XIAO Fan;JIANG Fei;QUO Qi;LU Baihua(National Electric Power Conversion and Control Engineering Technology Research Center(Hunan University),Changsha 410082,Hunan Province,China;School of Electrical and Information Engineering,Changsha University of Science and Technology,Changsha 410004,Hunan Province,China)

机构地区：[1]国家电能变换与控制工程技术研究中心(湖南大学),湖南省长沙市410082 [2]长沙理工大学电气与信息工程学院,湖南省长沙市410004

出　　处：《中国电机工程学报》2020年第20期6682-6693,共12页Proceedings of the CSEE

基　　金：国家自然科学基金(青年科学基金项目)(51707014);湖南省自然科学基金(青年科学基金项目)(2018JJ3534)。

摘　　要：针对弱电网下并网逆变器的稳定性控制问题,首先,构建一种对弱电网表现友好的新型锁相环结构,该新型锁相环能够附加必要的惯性与阻尼,抑制逆变器运行状态突变导致的锁相环输出频率幅值大幅度波动问题,并从阻抗的角度出发,对逆变器并网系统的等效输出阻抗相位特性进行重塑,提高其与电网阻抗交截频率处的相位裕度。该阻抗重塑控制策略分为新型锁相环阻抗重塑与逆变器控制环阻抗重塑2部分,然后,通过在新型锁相环结构的前级附加自适应谐振积分滤波器结构重塑锁相环阻抗,使可保持逆变器并网系统稳定的相角可行范围向低频段移动;在此基础上再对逆变器控制环阻抗进行重塑,使逆变器等效输出阻抗的相频特性向相角增大的方向移动,保证逆变器并网系统具有充足的相位裕度。阻抗重塑控制策略的引入在不牺牲锁相环带宽频率的情况下,不仅拓宽了并网逆变器对电网阻抗的适应范围,而且还提高了其电流控制的稳态和动态性能。最后,通过实验验证了所提理论分析的正确性以及所提控制策略的有效性。Aiming at the stability control problem of grid-connected inverters in weak grids, a new phase-locked loop structure that is friendly to weak grid was first constructed. The novel phase-locked loop can add the necessary inertia and damping to suppress the problem of large fluctuations in frequency amplitude caused by sudden changes in the operating state of the inverter. The phase characteristics of the inverter equivalent output impedance were reshaped from the perspective of impedance, and the phase margin at the intersection frequency of the inverter equivalent output impedance and grid impedance was improved degree. The impedance reshaping control strategy was divided into two parts: the novel phase-locked loop impedance reshaping and the inverter control loop impedance reshaping. The phase-locked loop was reshaped by adding an adaptive resonant integral filter structure in the front stage of the novel phase-locked loop structure. The impedance shifts the phase-frequency characteristic of the inverter equivalent output impedance to a low frequency band, broadening the feasible range of the phase angle that can maintain the stability of the system. On this basis, the inverter control loop impedance is reshaped, so that the phase-frequency characteristic of the inverter equivalent output impedance moves in the direction of increasing phase angle, ensuring that the inverter grid-connected system has sufficient phase margin. The introduction of the impedance reshaping control strategy not only widens the grid-connected inverter’s adaptability to the grid impedance without sacrificing the bandwidth of the phase-locked loop, but also improves the steady-state and dynamic performance of its current control. Experimental measurements verify the analysis.

关 键 词：弱电网 并网逆变器 锁相环 频率波动 自适应谐振积分滤波器 阻抗重塑 稳定裕度 

分 类 号：TM46[电气工程—电器]