光伏逆变并网系统阻抗建模及其稳定性分析  

Impedance modeling and stability analysis of PV grid-connected inverter system

作　　者：宋绍剑[1] 贺玮彤 刘斌[1] 陆益民[1] 廖碧莲[1] SONG Shao-jian;HE Wei-tong;LIU Bin;LU Yi-min;LIAO Bi-lian(School of Electrical Engineering, Guangxi University, Nanning 530004, China)

机构地区：[1]广西大学电气工程学院,广西南宁530004

出　　处：《广西大学学报（自然科学版）》2021年第4期935-947,共13页Journal of Guangxi University（Natural Science Edition）

基　　金：国家自然科学基金资助项目(61863003),广西自然科学基金资助项目(2016GXNSF AA380327)。

摘　　要：由于目前并网逆变系统的阻抗建模过程通常忽略了并网逆变器内部的频率耦合效应及其与前级变换器的相互影响,造成稳定分析结果不准确的问题。为此,提出一种考虑频率耦合的组串式光伏逆变并网系统阻抗建模方法。首先,利用模糊控制与PID控制的等效原理拟合出一类模糊MPPT控制的等效传递函数;然后,采用多谐波线性化小信号建模方法建立了一种考虑频率耦合且包含MPPT环节的组串式光伏并网系统整体阻抗模型,并详细分析了直流母线动态对并网逆变系统阻抗特性和稳定性的影响;最后,通过RT-LAB硬件在环仿真实验验证了所提方法的有效性和先进性。结果表明,与非计及频率耦合的阻抗模型相比,考虑频率耦合且包含MPPT环节的阻抗模型更为精确能够更加准确地分析系统的稳定性,并准确预测系统潜在的谐振点。The impedance modeling process of grid-connected inverter,the frequency coupling effect inside the grid-connected inverter and its interaction with the pre-stage converter are usually ignored,which leads to inaccurate stability analysis results.For this reason,a method for impedance modeling of string photovoltaic grid-connected inverter considering frequency coupling is proposed.First,we utilized the equivalent principle of fuzzy control and PID control to fit a class of equivalent transfer function of fuzzy-based MPPT control.And then we adopted the harmonic linearization small-signal modeling method to establish an overall impedance model of the string photovoltaic grid-connected inverter,which considers the frequency coupling and the MPPT control strategy.Besides,influences of the DC bus dynamic on the impedance characteristics and stability of the grid-connected inverter was analyzed in detail.Finally,the proposed method was verified by RT-LAB hardware-in-the-loop simulation experiments.The results show that,compared with the non-coupled impedance model,the impedance model that considers frequency coupling and includes MPPT control is more accurate in that it can predict the potential resonance point of the system,and analyze the stability of the system accurately.

关 键 词：阻抗建模 并网逆变器 光伏 频率耦合 最大功率点跟踪 

分 类 号：TM464[电气工程—电器]