基于电网阻抗辨识的并网逆变器稳定性分析

发布时间：2018-03-12 13:00

本文选题：并网逆变器　切入点：电网　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：在分布式新能源发电大量增加及电网智能化的发展趋势下,电网系统的构成及其动态特性变得愈加复杂,导致其稳定性更加容易受到影响。新能源发电多数通过逆变器并网,系统中各逆变器之间存在不同程度的差异,引起不同形式的兼容性问题。其中由于阻抗不匹配而引起的谐波振荡问题尤为关键,严重时可导致整个发电网络的瘫痪。对于分布式发电系统中某一独立逆变器来说,除自身外其他逆变器等效总体阻抗对其稳定性的影响可通过电网阻抗反映。因此,本课题以电网阻抗辨识为基础,对并网逆变器的稳定性进行分析,对保证电网系统的稳定运行具有一定的意义。首先对电网阻抗在线辨识的实现方案进行了研究,分析了脉冲响应分析法的基本原理,对其扰动注入和响应分析部分进行了具体设计,验证了其所具有的快速性及宽频带特性。在仿真中对电网阻抗在线辨识方案进行了验证,分析了辨识过程中的响应波形及辨识结果的影响因素。利用谐波线性化方法建立了逆变器控制系统中锁相环及电流控制的小信号模型,结合逆变器主电路平均模型,得到了逆变器输出阻抗的频域模型,并以频率扫描的方式在仿真中对其进行了验证。确定了逆变器输出阻抗的影响因素,为后续的稳定性分析奠定了基础。利用电网阻抗及逆变器输出阻抗模型,采用基于阻抗的稳定性分析方法,分析了电网阻抗对并网逆变器稳定性的影响。根据稳定性分析结果及逆变器输出阻抗的影响因素,确定了解决谐振问题的方法。通过仿真,将稳定性分析理论与逆变器系统的时域响应联系到一起,对分析方法做出了验证。最后建立了并网逆变器稳定性分析实验平台,并在实验平台中进行了电网阻抗在线辨识及稳定性分析实验,对各项研究内容做出了验证。
[Abstract]:With the increase of distributed new energy generation and the development trend of intelligent power grid, the composition and dynamic characteristics of power system become more complex, which makes its stability more vulnerable. There are different degrees of differences among the inverters in the system, which cause different kinds of compatibility problems, among which the harmonic oscillation caused by impedance mismatch is particularly critical. For an independent inverter in a distributed generation system, the effect of the equivalent total impedance of the inverter other than itself on its stability can be reflected by the grid impedance. Based on grid impedance identification, this paper analyzes the stability of grid-connected inverter, which has a certain significance to ensure the stable operation of power system. Firstly, the realization scheme of on-line identification of grid impedance is studied. The basic principle of impulse response analysis is analyzed, and its disturbance injection and response analysis are designed to verify its rapidity and broadband characteristics. In the simulation, the on-line identification scheme of power network impedance is verified. The response waveform in the identification process and the influencing factors of the identification results are analyzed. The small signal model of phase-locked loop and current control in inverter control system is established by using harmonic linearization method, and combined with the average model of inverter main circuit. The frequency domain model of the output impedance of the inverter is obtained, and it is verified in the simulation by frequency scanning. The influence factors of the output impedance of the inverter are determined. It lays a foundation for the subsequent stability analysis. Using the power grid impedance and inverter output impedance model, the impedance based stability analysis method is adopted. The influence of grid impedance on the stability of grid-connected inverter is analyzed. According to the results of stability analysis and the influence factors of inverter output impedance, the method of solving resonance problem is determined. The stability analysis theory is combined with the time-domain response of the inverter system, and the analysis method is verified. Finally, a grid-connected inverter stability analysis experimental platform is established. The on-line identification and stability analysis experiments of power system impedance are carried out on the experimental platform, and the research contents are verified.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM464

【参考文献】