弱电网条件下并网逆变器控制系统的稳定性分析
发布时间：2018-09-19 06:21
【摘要】：随着分布式发电系统的迅速发展,并网逆变器得到广泛应用。由于在地处偏远的分布式发电系统中,长距离的传输线以及大量变压装置的存在给电网带来一个不可忽略的等效阻抗,使得电网呈弱电网特性。因此,弱电网和并网逆变器之间构成交互式系统,电网阻抗将会对并网逆变器控制系统的稳定性造成一定的影响。本文主要研究了弱电网条件下电网阻抗对并网逆变器稳定性的影响。首先,对基于LCL滤波的并网逆变器控制系统进行小信号建模,给出了比例谐振(PR)调节器参数设计方案。以电感-电阻(L-R)串联模型作为弱电网模型,分析了电网阻抗所带来的逆变器控制系统的稳定性问题。然后,分析了几种常用的阻抗测量方法,并选取了小信号注入法作为弱电网阻抗的在线测量手段。同时,论文对无源阻尼和有源阻尼两种常用的谐振抑制方案进行了进一步的分析,在此基础上引出了混合阻尼抑制方案,并与电网阻抗测量技术相结合,组成了基于混合阻尼的并网逆变器自适应控制策略,使得并网逆变器在各种电网阻抗条件下都可以保持较为优良的系统特性。最后论文根据系统的要求,设计并搭建了一台基于数字控制的1.5kW并网逆变器实验平台,给出了硬件和软件设计过程,并在此平台上完成了电网阻抗对并网逆变器稳定性影响实验,验证了混合阻尼自适应控制方案的正确性和可行性。
[Abstract]:With the rapid development of distributed generation system, grid-connected inverter is widely used. In the remote distributed generation system, the existence of long distance transmission lines and a large number of voltage transformers brings a non-negligible equivalent impedance to the power network, which makes the power network show weak network characteristics. Therefore, there is an interactive system between the weak grid and grid-connected inverter, and the impedance of the grid will affect the stability of the grid-connected inverter control system. In this paper, the influence of grid impedance on the stability of grid-connected inverter is studied. Firstly, the control system of grid-connected inverter based on LCL filter is modeled with small signal, and the parameter design scheme of proportional resonant (PR) regulator is presented. Taking the inductance resistance (L-R) series model as the weak grid model, the stability of the inverter control system caused by the power grid impedance is analyzed. Then, several commonly used impedance measurement methods are analyzed, and the small signal injection method is selected as the on-line measurement method of the impedance of weak electric network. At the same time, two common resonant suppression schemes, passive damping and active damping, are further analyzed in this paper. On this basis, a hybrid damping suppression scheme is proposed, which is combined with the impedance measurement technology of power network. The adaptive control strategy of grid-connected inverter based on hybrid damping is formed, which makes the grid-connected inverter keep excellent system characteristics under various grid impedance conditions. Finally, according to the requirements of the system, an experimental platform of 1.5kW grid-connected inverter based on digital control is designed and built, and the design process of hardware and software is given. On this platform, the influence of grid impedance on the stability of grid-connected inverter is completed, and the correctness and feasibility of hybrid damping adaptive control scheme are verified.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464
本文编号：2249302
[Abstract]:With the rapid development of distributed generation system, grid-connected inverter is widely used. In the remote distributed generation system, the existence of long distance transmission lines and a large number of voltage transformers brings a non-negligible equivalent impedance to the power network, which makes the power network show weak network characteristics. Therefore, there is an interactive system between the weak grid and grid-connected inverter, and the impedance of the grid will affect the stability of the grid-connected inverter control system. In this paper, the influence of grid impedance on the stability of grid-connected inverter is studied. Firstly, the control system of grid-connected inverter based on LCL filter is modeled with small signal, and the parameter design scheme of proportional resonant (PR) regulator is presented. Taking the inductance resistance (L-R) series model as the weak grid model, the stability of the inverter control system caused by the power grid impedance is analyzed. Then, several commonly used impedance measurement methods are analyzed, and the small signal injection method is selected as the on-line measurement method of the impedance of weak electric network. At the same time, two common resonant suppression schemes, passive damping and active damping, are further analyzed in this paper. On this basis, a hybrid damping suppression scheme is proposed, which is combined with the impedance measurement technology of power network. The adaptive control strategy of grid-connected inverter based on hybrid damping is formed, which makes the grid-connected inverter keep excellent system characteristics under various grid impedance conditions. Finally, according to the requirements of the system, an experimental platform of 1.5kW grid-connected inverter based on digital control is designed and built, and the design process of hardware and software is given. On this platform, the influence of grid impedance on the stability of grid-connected inverter is completed, and the correctness and feasibility of hybrid damping adaptive control scheme are verified.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464
【参考文献】
相关期刊论文 前1条
1 刘飞;段善旭;查晓明;;基于LCL滤波器的并网逆变器双环控制设计[J];中国电机工程学报;2009年S1期
，本文编号：2249302
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