光伏发电系统无缝切换控制策略研究

发布时间：2018-05-27 04:30

本文选题：光伏发电系统 + 无缝切换　；参考：《上海电力学院》2016年硕士论文

【摘要】：随着传统化石能源的消耗与人们对环境问题的关注,太阳能等清洁能源受到越来越多的关注。为了保证资源的充分利用,并网与孤岛运行模式间的无缝切换是充分利用新能源的前提。本文搭建了基于电压控制型逆变器的光伏发电系统,给出了逆变器的控制参数设计,建立了数学模型。分析了空载情况下幅值和频率的输出特性,设计了虚拟阻抗的控制。带载情况下,针对幅值和频率下跌问题,通过对虚拟阻抗上功率损耗值的反馈,给出了参考值精确的补偿方案。传统的同步控制中,频率调节和相角调节相互干扰,分别调节降低了并网的时效性。本文提出了两种自同步并网控制方案,基于频率的自同步控制方案和基于相角差的自同步控制方案。两种方法都将传统的频率调节和相角调节统一,简化了控制,提高了并网的时效性。对二次调压和二次调频进行了稳定性分析,另外,还将同步检测单元与逆变器的控制相结合,简化了控制。通过仿真和实验验证了所提的控制策略。结合电压控制型逆变器,针对于传统的间接幅值和频率扰动法,给出了两种主动式孤岛检测方案:主动幅值扰动法和主动频率扰动法,直接扰动输出电压的幅值和频率。低压配电网中,线路阻抗呈阻性,传统的功率解耦存在着问题,本文通过虚拟阻抗的设计,使得逆变器输出阻抗呈现感性,实现了并网运行下的功率解耦控制。重点讨论了并网向孤岛运行的无缝切换控制策略,通过并网和孤岛模式切换时参考值连续性的设计,来保证模式间的平滑切换,详细的分析了调频轴调压轴与输出功率的关系,给出了保证调节轴参考值连续的数学表达式,在轻载和重载两种情况下分别做了仿真,仿真结果与理论推导相吻合。
[Abstract]:With the consumption of traditional fossil energy and attention to environmental problems, more and more attention has been paid to clean energy such as solar energy. In order to make full use of resources, the seamless switching between grid-connected and islanding operation mode is the premise of making full use of new energy. In this paper, the photovoltaic power generation system based on voltage controlled inverter is built, the control parameters of the inverter are designed, and the mathematical model is established. The output characteristics of amplitude and frequency under no-load are analyzed, and the control of virtual impedance is designed. In the case of load, the exact compensation scheme of reference value is given by feedback of power loss value on virtual impedance for the problem of amplitude and frequency drop. In traditional synchronous control, frequency regulation and phase angle regulation interfere with each other, which reduces the time efficiency of grid connection. In this paper, two kinds of self-synchronization control schemes are proposed, which are frequency based self-synchronization control and self-synchronization control based on phase angle difference. Both methods unify the traditional frequency regulation and phase angle regulation, simplify the control and improve the timeliness of grid-connected. The stability of secondary voltage regulation and secondary frequency modulation is analyzed. In addition, the synchronous detection unit is combined with the control of inverter to simplify the control. The proposed control strategy is verified by simulation and experiment. According to the traditional indirect amplitude and frequency perturbation methods, two active islanding detection schemes are presented: the active amplitude perturbation method and the active frequency perturbation method, and the amplitude and frequency of the output voltage are directly disturbed. In the low voltage distribution network, the line impedance is resistive, and the traditional power decoupling problem exists. Through the design of the virtual impedance, the output impedance of the inverter is inductive, which realizes the power decoupling control under the grid-connected operation. The seamless switching control strategy of grid-connected operation to islanding is discussed in detail. The smooth switching between modes is ensured by the design of continuity of reference values in grid-connected and island-mode switching. The relationship between the output power and the adjustable compression shaft of the FM axis is analyzed in detail. The mathematical expressions to ensure the continuity of the reference value of the adjusting shaft are given. The simulation results are in good agreement with the theoretical derivation in the case of light load and heavy load.
【学位授予单位】：上海电力学院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM615

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