【作者】 高红亮；

【导师】 汪秉文；

【作者基本信息】 华中科技大学 ， 控制理论与控制工程， 2013， 博士

【摘要】 随着全球气候的变化和人口的快速增长,在全球范围内人们对电能的需求不断增加,使得电力系统负荷不断加重。同时,电力系统已步入了大电网、大机组、跨区域联网的新阶段,长距离互联线路广泛存在。这些因素容易导致低频振荡的产生,电力系统低频振荡如果得不到有效的抑制,将会引起连锁故障,造成大面积的停电,产生巨大的损失。由于电力系统的不断发展及其本身存在的非线性、时变性、强约束强耦合等特点,使得电力系统的低频振荡控制技术还有很多问题并没有完全解决,值得进一步研究。本文从电力系统的实际需求出发,对电力系统低频振荡的控制技术进行了研究。本文首先对电力系统低频振荡机理进行了研究,深入研究低频振荡的产生机理有助于采取有效的控制方法来抑制系统的低频振荡。文中分析了低频振荡机理研究的现状,对负阻尼机理、共振或谐振机理、非线性机理分别进行了论述,并对各自的特点进行了分析。接着以发电机阻尼系数的解析表达式为基础,对影响发电机阻尼系数的各种因素进行了分析,最后以发电机转子运动方程为基础,提出电力系统低频振荡的阻尼系数机理,得到阻尼系数对低频振荡影响的具体结论。文中对电力系统动态研究的实用模型进行了求解。在研究过程中,从电力系统的基本方程入手,通过对基本方程进行小偏差线性化处理和数学求解,从而求得以本地易测量为状态量的单机无穷大系统三阶状态方程数学模型,并给出了模型求解算法的具体步骤,最后结合实际数据求得了开封电网的数学模型,为基于数学模型的分散控制器的设计打下基础。本文提出了基于系统阻尼比的最优励磁控制器的设计方法。针对常规多变量反馈最优控制存在的不足之处,结合无阻尼机械振荡频率的不变性,求解得到基于系统阻尼比的最优反馈增益矩阵,进而得到基于系统阻尼比的最优励磁控制器设计方法。最后,通过对开封电网和豫东电网的仿真研究说明了所设计控制器具有比常规最优励磁控制器和电力系统稳定器更好的控制效果。结合新一代的智能控制技术,论文对基于Mamdani模糊推理的电力系统智能控制进行了研究。基于比例积分微分(PID)励磁控制原理和模糊PID励磁控制器的组成原理,本文设计了基于Mamdani模糊推理的PID励磁控制器(MFPID),并给出了基于Mamdani模型的模糊逻辑单元的详细设计过程和MFPID控制器的算法实现。进一步地,结合常规电力系统稳定器(PSS)的优点,提出了结合PSS和MFPID的分段切换控制策略。最后通过仿真研究说明了所设计控制器的有效性。更多还原

【Abstract】 With the global climate change and rapidly growth of population, the demand of electric energy is continuously increasing globally, which made the load of power system heavier continuously. Meanwhile, power system has stepped into a new stage of large power grid, large generator unit and interregional interconnection, and long distance interconnection electric transmission lines exist extensively. These factors lead to the generation of low frequency oscillation easily. If power system low frequency oscillation can not be suppressed effectively, it will cause cascading outages, large area power cutting and big losses. Due to continuous development of power system and its nonlinear, time-varying, strong constraint and close coupling characteristics, many problems of power system low frequency oscillation control technology are not solved totally and worthy of further research. From the actual needs of power system, the control technology of power system low frequency oscillation is studied.In this dissertation, the mechanism of power system low frequency oscillation is studied. In-depth studies of the production mechanism of low frequency oscillation are helpful for adopting effective control method for suppression of low frequency oscillation. The research status of the mechanism of low frequency oscillation is analyzed in this dissertation. Negative damping mechanism, resonance or harmonic mechanism, and nonlinear mechanism are discussed separately, and the particular features of each mechanism are analyzed. Then various influencing factors of generator damping coefficient are analyzed based on the analytical expression of generator damping coefficient. Finally, the damping coefficient mechanism of power system low frequency oscillation is put forward, and the specific conclusions of the influence of damping coefficient on low frequency oscillation are obtained based on the motion equations of generator rotor.The practical model for power system dynamic research is solved in this dissertation. During the research, the basic power system equations are processed by small deviation linearization and mathematical solution, then the third-order state equation mathematical model for the single-machine infinite-bus power system is obtained, the state variables of the model are local quantities which are easy to measure, and the concrete steps of model solution algorithm are given. At last, the mathematical model of Kaifeng power grid is obtained referring to practical data, which lay a foundation for the design of decentralized controllers based on mathematical model.In this dissertation, the design method of the optimal excitation controller based on the damping ratio of a system is presented. In view of disadvantages of conventional multivariable feedback optimal control, the optimal feedback gain matrix based on the damping ratio of a system can be solved according to the invariance of undamped mechanical oscillation frequency, and then the design method of optimal excitation controller based on the damping ratio of a system is obtained. Finally, the simulation study is carried out on Kaifeng power grid and Yudong power grid. Simulation results show that the controller designed has better control effect relative to the conventional optimal excitation controller and power system stabilizer.Combing the new generation intelligent control technology, the power system intelligent control based on Mamdani fuzzy inference is studied in this dissertation. The proportional integral derivative (PID) excitation controller based on Mamdani fuzzy inference (MFPID) is designed according to PID excitation control principle and the composition principle of fuzzy PID excitation controllers. The detailed design process of fuzzy logic unit based on Mamdani model and algorithm implementation of MFPID controller is presented. Combing advantages of conventional power system stabilizer (PSS), the segmentation switch control strategy is proposed by combing PSS and MFPID further. Finally, the effectiveness of the controller designed is illustrated by simulation.更多还原