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1、摘 要摘 要本文针对发电机励磁系统的非线性及易受内、外扰动等特点,应用坐标变换,ESO及滑模变结构控制理论,设计了一种新颖的提高系统动、静态特性的ESO滑模励磁控制器,并在此基础上又新引入电压反馈,使其更好的稳定发电机端电压。其主要内容如下:首先对励磁系统的状态方程进行坐标变换。把单机无穷大励磁系统三阶模型写成标准仿射非线性形式,根据非线性系统的状态反馈线性化理论进行坐标变换,这样系统的非线性因素都集中到含有控制输入的方程中。如果直接反馈线性化会让控制器的设计变得复杂,所以本文采用扩张状态观测器观测该部分。本文构造了一个二阶的ESO来估计系统的非线性部分。这样经过扩张状态观测器反馈之后系统变成
2、线性系统,可以按照线性系统来设计,由于滑模变结构控制具有响应速度快、不需要在线辨识、对参数变化及各种扰动不敏感等优点,本文采取了滑模设计。滑模变结构控制器的设计主要包括两个部分:切换函数的设计和滑模控制律的设计。为了减少滑模变结构控制的抖振现象,本文选取指数趋近率控制方式,通过对指数趋近率参数和的调整可以减弱控制信号的抖振并保证滑动态模品质。再用准滑动模态控制原理,即用饱和函数替代符号函数,就可以进一步地减弱滑模控制的抖振现象。然而此时所得的控制器并没有考虑对励磁系统机端电压偏差的调节,会失去维持发电机端电压稳定的能力。所以在所设计的最后控制规律的基础上附加一个比例环节,再选定合适的比例系数来
3、平衡发电机端电压。这样增加一个反馈量就能很好维持机端电压的稳定。文章的最后对带励磁的单机无穷大系统进行数值仿真。通过对大、小扰动的仿真表明,该控制器在动态、静态特性上明显的提高了系统的稳定性、快速性和准确性,且鲁棒性好。关键词:电压反馈;扩张状态观察器;励磁系统;滑模控制;鲁棒性IAbstractAbstractIn this paper, a new ESO sliding mode controller that can improve the system stability was designed ,as to apply to the strong nonlinear of gen
4、erator excitation system and the characteristics vulnerable to external disturbance, which cater to feedback linearization, ESO and sliding model variable structure control theory. on this basis we introduce new voltage feedback, make it more stable voltage of the machine. Firstly, make the coordina
5、te transformation for excitation system state equations. Purpose is to the single machine infinite excitation system three order model written in standard form of affine nonlinear, according to the nonlinear systems state feedback linearization theory for coordinate transformation, this system of no
6、nlinear factors are concentrated to the containing control input equations. If make the direct feedback linearization controller will let design become complex, so this paper uses the extended state observer observing the part.This paper constructs a two order ESO to estimate the system nonlinear pa
7、rt. After this extended state observer feedback system into a linear system, according to the linear system to design, because the sliding mode variable structure control has quick response speed, without the need for on-line identification of parameter variations and disturbances. It is not sensiti
8、ve, this paper takes the design of sliding mode.Designing the sliding mode variable structure controller mainly consists of two parts: the design of switching function and the sliding mode control law design. In order to reduce the sliding mode variable structure control chattering phenomenon, this
9、paper selects the exponential reaching law control method, based on the exponential reaching law parameters and adjustment can be diminished to the control signal and to ensure the smooth buffeting dynamic model quality. Then the quasi sliding mode control theory, namely the saturation function inst
10、ead of sign function, can further reduce the chattering phenomenon in sliding mode control.But the controller did not account for the excitation system of generator terminal voltage deviation adjustment and will lose the ability to maintain the generator terminal voltage stability. So in the final d
11、esign control law based on the additional proportional system, we selected a suitable proportion coefficient to balance the generator terminal voltage. This adds a feedback and can be very good to maintain generator terminal voltage stability.Last we make the excitation of single machine infinite sy
12、stem numerical simulation. By the large, small perturbations in the simulation results show that, the controller in the dynamic, static characteristics obviously improved the systems stability, speed and accuracy, and good robustness.Key words: Voltage feedback; ESO; Excitation system; Sliding mode
13、control; RobustnessIX目 录目 录摘要IAbstractII第1章 绪论11.1课题的背景11.2发电机励磁系统控制方式的发展及现状11.2.1励磁系统单变量控制阶段21.2.2励磁系统线性多变量控制阶段31.2.3励磁系统非线性多变量控制阶段51.3本文的主要工作5第2章 扩张状态观测器(ESO)及其仿真72.1自抗扰控制技术72.2扩张状态观测器72.2.1状态观测器82.2.2扩张状态观测器(ESO)92.2.3ESO用于动态补偿线性化132.2.4 扩张状态观测器的仿真152.3本章小结18第3章 滑模变结构控制理论203.1引言203.2滑模变结构控制理论作用机理
14、213.2.1滑动模态的基本概念及数学模型213.2.2滑模变结构控制的定义233.3 滑模变结构控制抖振现象233.3.1滑模变结构控制抖振产生的原因243.3.2滑模变结构控制抗抖振措施243.4连续系统的滑模控制253.4.1滑动模态的存在与到达的条件253.4.2等效控制263.4.3滑动模态运动方程273.5滑模控制器设计步骤283.6趋近律滑模控制器设计283.6.1常见趋近律的形式293.6.2趋近律滑模控制的原理293.7本章小结30第4章 同步发电机励磁系统314.1发电机励磁系统组成及数学模型314.1.1同步发电机系统的传递函数324.1.2发电机励磁调节器的表达式324
15、.1.3交流励磁机的数学模型344.2带励磁的单机无穷大系统数学模型的构造354.3发电机励磁系统运行要求384.4本章小结38第5章 带电压反馈励磁系统ESO滑模控制器设计405.1微分几何理论相关概念405.1.1引言405.1.2仿射非线性系统405.1.3向量场415.1.4导出映射的概念415.1.5Lie导数与Lie括号415.1.6控制系统的关系度435.1.7非线性系统的线性化标准型435.2基于微分几何非线性控制理论特点465.3带励磁控制的电力系统状态方程及变换475.3.1带励磁系统的状态方程模型475.3.2坐标变换475.4励磁系统控制器的设计485.4.1构造二价ESO485.4.2带电压反馈的ESO励磁滑模控制器设计495.5仿真研究515.6本章小结54结论55参考文献57攻读学位期间取得的研究成果及发表的学术论文61致谢62 第1章 绪 论第1章 绪 论1.1课题的背景在20世纪60年代,用发电机励磁控制提高电力系统稳定性取得了巨大进步,因此励磁控制已成为全面提高系统按全稳定性的必选手段。近年来,