弱电网情况下光伏并网逆变器的稳定性研究

发布时间：2018-05-15 09:30

本文选题：弱电网 + LCL滤波　；参考：《天津大学》2014年硕士论文

【摘要】：随着能源问题的日益突出,分布式发电以其清洁、高效、可再生等优势越来越广泛地被应用于电力系统当中,然而相对于传统发电技术,分布式发电系统中电力电子装置的并网存在稳定性的隐患。分布式发电的应用以及远距离输电线路的架设也向电网引入了大量线路阻抗,使电网呈现出弱电网的特性,进一步将电网-并网逆变器构成的交互系统的稳定性问题复杂化。本文以交互系统Middlebrook判据为基础,阐明了这种不稳定性的产生机制,给出了逆变器-电网交互系统的稳定性判据,对比分析了不同电流控制器及滤波器配置下,电网阻抗对于系统稳定裕度的影响,并从频域的角度具体研究了电网阻抗对系统低频段高频段的影响。指出电网阻抗会导致低频段准谐波控制器中的谐波补偿尖峰随着阻抗值的增大而进入系统带宽外,威胁系统的稳定性,另外还会导致高频段LCL滤波器产生的谐振尖峰发生偏移,进而影响有源阻尼控制器的有效性,导致系统失稳。本文由此提出了针对这两种情况的解决方案,在基于带通滤波器有源阻尼控制方法的基础上引入自适应陷波滤波器,实现了一种自适应的有源阻尼控制方法,并通过增加电网感抗实时检测校正环节,补偿了当电网失真情况下的前馈控制的不稳定性,实现了自适应并网电流控制策略。两种方法都依赖于准确的电网阻抗实时检测,从有源阻尼控制以及含前馈控制的闭环电流跟踪控制两个方向解决了系统谐振尖峰随电网参数变化而发生位移的问题,提高了并网逆变系统的稳定裕度。最后基于Matlab/Simulink平台搭建了7.7kW单相并网逆变仿真模型,并基于TMS320F28335控制芯片设计了440W并网逆变器实验平台,仿真实验结果支持了本文理论分析,佐证了基于自适应陷波滤波器的有源阻尼控制方法的有效性及自适应性。
[Abstract]:With the increasingly prominent energy problem, distributed generation is more and more widely used in power system because of its advantages of clean, efficient and renewable. However, compared with traditional power generation technology, distributed generation is more and more widely used in power system. In the distributed generation system, there is a hidden danger of the stability of the power electronic device connected to the grid. The application of distributed generation and the erection of long-distance transmission lines also introduce a large number of line impedance to the power network, which makes the power grid show the characteristic of weak grid, and further complicates the stability of the interactive system composed of grid-connected inverter. Based on the Middlebrook criterion of interactive system, this paper clarifies the mechanism of the instability, gives the stability criterion of inverter-grid interactive system, and compares and analyzes the different current controller and filter configuration. The influence of power grid impedance on the stability margin of the system is studied. The influence of power grid impedance on the low frequency band and high frequency band of the system is studied from the point of view of frequency domain. It is pointed out that the impedance of the power network will cause the harmonic compensation spike in the low frequency band quasi harmonic controller to enter the system bandwidth with the increase of the impedance value, which will threaten the stability of the system. In addition, it will also lead to the shift of the resonant spike produced by the LCL filter in the high frequency band. Furthermore, the effectiveness of the active damping controller is affected, which leads to the instability of the system. In this paper, an adaptive notch filter is introduced based on the active damping control method of bandpass filter, and an adaptive active damping control method is realized. The instability of feedforward control is compensated by adding real-time detection and correction link of reactance, and the adaptive grid-connected current control strategy is realized. Both methods depend on accurate real-time detection of power system impedance. The problem of the displacement of the system resonance spike with the change of the network parameters is solved from the active damping control and the closed-loop current tracking control with feedforward control. The stability margin of grid-connected inverter system is improved. Finally, the simulation model of 7.7kW single-phase grid-connected inverter is built based on Matlab/Simulink platform, and the experiment platform of 440W grid-connected inverter is designed based on TMS320F28335 control chip. The simulation results support the theoretical analysis of this paper. The validity and adaptability of the active damping control method based on adaptive notch filter are proved.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464;TM615

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