含多逆变器的孤岛微电网动态建模与稳定性分析

发布时间：2018-06-13 21:38

本文选题：微电网 + 动态相量法　；参考：《兰州理工大学》2017年硕士论文

【摘要】：微电网是分布式能源的有效利用形式。在孤岛微电网中,大量的分布式发电单元通过逆变器接入系统,使孤岛微电网系统的电磁暂态模型变得更加复杂,而且逆变型微源具有惯性小、高频非线性的特性,使孤岛微电网系统的稳定性易受到扰动影响。为了对孤岛运行下微电网的动态特性进行研究,并从机理上分析影响系统稳定性的因素,建立微电网动态模型并分析其稳定性是很有必要的。基于对电压源型逆变器典型模型的对比分析,采用动态相量法对三相电压源型逆变器进行建模。将三相电压源型逆变器的动态相量模型和电磁暂态模型进行仿真对比,表明两种动态模型的仿真结果是一致的。将动态相量法用于描述三相电压源型逆变器稳态特性和主要的动态变化,并将其用于含多个逆变器的孤岛微电网系统的仿真与分析。采用动态相量法建立了含多逆变器三相平衡孤岛微电网系统的动态相量模型,并应用奇异摄动法分别推导了不同时间尺度下孤岛微电网的降阶动态相量模型。在MATLAB/Simulink中构建孤岛微电网的动态相量模型,电流和频率的仿真波形说明所建立的动态模型可以准确地描述系统的动态特性,将完整动态相量模型与降阶动态相量模型的仿真结果进行比较,验证了降阶模型的正确性。仿真研究表明,下垂控制系数越大,系统的响应速度越快,但是当超过一定的值时系统会失去稳定。为了分析所建立孤岛微电网动态相量模型的小信号稳定性,采用李亚普诺夫第一方法将模型进行小信号线性化,然后根据特征值判据判断系统的稳定性,并由频率下垂控制系数增加时系统根轨迹变化情况得出能使微电网保持稳定运行的控制参数取值范围,研究结果表明降阶动态相量模型能预测系统的不稳定。论文得出的使系统保持小信号稳定的控制参数取值范围可应用于P/f控制器的设计。
[Abstract]:Microgrid is an effective form of distributed energy utilization. In the isolated island microgrid, a large number of distributed generating units are connected to the system by inverter, which makes the electromagnetic transient model of the isolated microgrid system more complex, and the inverter microsource has the characteristics of small inertia and high frequency nonlinearity. The stability of isolated microgrid system is vulnerable to disturbance. In order to study the dynamic characteristics of microgrid under isolated island operation and analyze the factors affecting the system stability from the mechanism, it is necessary to establish the dynamic model of microgrid and analyze its stability. Based on the comparison and analysis of typical models of voltage source inverter, the dynamic phasor method is used to model the three phase voltage source inverter. The dynamic phasor model and electromagnetic transient model of three-phase voltage source inverter are simulated and compared. The results show that the simulation results of the two dynamic models are consistent. The dynamic phasor method is used to describe the steady-state characteristics and main dynamic changes of three-phase voltage source inverter, and it is applied to the simulation and analysis of isolated microgrid system with multiple inverters. The dynamic phasor model of a three-phase balanced islanding microgrid system with multi-inverter is established by using the dynamic phasor method, and the reduced order dynamic phasor model of the islanding microgrid with different time scales is derived by using the singular perturbation method. The dynamic phasor model of isolated microgrid is constructed in MATLAB / Simulink. The simulation waveform of current and frequency shows that the dynamic model can accurately describe the dynamic characteristics of the system. The simulation results of the complete dynamic phasor model and the reduced order dynamic phasor model are compared to verify the correctness of the reduced order phasor model. The simulation results show that the larger the sag control coefficient, the faster the response speed of the system is, but the system will lose stability when it exceeds a certain value. In order to analyze the small signal stability of the dynamic phasor model of isolated microgrid, the Lyapunov first method is used to linearize the model, and then the stability of the system is judged according to the eigenvalue criterion. The range of control parameters which can keep the microgrid running stably can be obtained from the change of system root locus when the frequency droop control coefficient increases. The research results show that the reduced order dynamic phasor model can predict the instability of the system. It is concluded that the range of control parameters which can keep the system small signal stable can be applied to the design of P / F controller.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM712

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