考虑励磁限幅和数字式电液调速器的电力系统非线性协调控制

The linearized method based excitation control mode of AVR+PSS will have poor control effect when the operation state shift largely. And the existing nonlinear control design methods do not consider the dynamics of the AVR as well as the excitation limit, which therefore can not ensure the terminal voltage control effect and transient stability of the system. This project propose a nonlinear auxiliary excitation control method. Power system structure preserving is built with AVR dynamics and the limitation of excitation. Then, the generalized Hamiltonian realization is accomplished in a neighborhood near the equilibrium point. Based on the energy characteristics of the system, the inequality condition is represented with the switching control process of the system. The excitation control law, which can achieve the asymptotic stability of the system, is derived using the common Lyapunov function. Then, we try to strength the transient stability of the system by taking advantage of the fast adjusting ability of the digital electro-hydraulic governor(DEH) with respect to the mechanical power. The system model with excitation and DEH is built and the generalized dissipation Hamilton structure is achieved. Using the coupling characteristics in terms of the transient energy regulation, the functions of the excitation and DEH controllers are analyzed within a unified structural framework. The coordinated adaptive control strategy between excitation and DEH is proposed in the point of view rapidly reducing the transient energy of the system. The study on this subject will promote the development of the stability control theory of the differential-algebra system with inequality constraints and improve the power system stability control strategy configuration in the whole dynamic process.

采用线性化方法设计的AVR+PSS励磁控制在系统运行点偏移较大时控制效果不佳，而现有非线性励磁控制设计未考虑AVR动态和励磁限幅，难同时保证机端电压控制和系统暂态稳定。本项目提出非线性辅助励磁控制方式，构建含AVR动态和限幅的系统结构保留模型，在平衡点附近某一邻域进行系统广义Hamilton实现，把握系统能量特性，将不等式约束转化为系统切换控制过程，选定共同Lyapunov函数并导出可使系统渐近稳定的励磁控制规律；利用数字电液调速器(DEH)快速调节机械功率以提高系统暂态稳定性，建立含励磁和DEH的系统模型并进行广义耗散Hamilton实现，利用在调节系统暂态能量方面的耦合特性，在统一结构框架内分析励磁和DEH控制作用，从快降低系统暂态能量角度给出励磁与DEH间的协调自适应控制策略。本课题的研究将推动含不等式约束的微分-代数系统稳定性控制理论的发展，完善电力系统全过程稳定控制策略配置方案。

随着特高压、可再生能源和智能电网技术的发展，电网所含元件和运行状态更加复杂，电网运行趋于其稳定极限，电网暂态稳定仍然是威胁系统安全的重大隐患。与此同时，电力系统建模更为困难且难以获取精确通用模型，传统的基于数值仿真的电网稳定分析和控制手段受到极大挑战。. 本项目研究发电机励磁AVR动态特性和限幅环节在维持机端电压和提高系统暂态稳定方面的具体作用，分析基于线性化方法所设计的PSS控制环节的作用区间和在提高大扰动后系统暂态稳定性方面的不足；以AVR作为主控制通道和内环控制，建立能提高系统暂态稳定性同时兼顾机端电压控制效果和系统动态稳定性的模糊自适应鲁棒稳定控制策略。从自治Hamilton系统周期解理论出发，将基于变分法和极值原理的非线性系统固有周期轨道存在性的判断理论和计算方法应用于电网低频振荡频率特性分析；在单机无穷大系统基础上详细推导了系统低频振荡存在的条件和固有频率的计算方法，并与线性化基础上的特征值分析法所得结论进行比较；从系统的非线性动力学性质出发分析电网存在低频振荡现象的物理本质，讨论与低频振荡频率特性密切相关的因素，并用数值仿真进行验证；从改变系统固有周期轨道角度讨论降低发生低频振荡事故概率的可能性。最后，基于PMU的实时量测结果，获取适于在线应用的电力系统数值等效模型，利用改进Prony算法分析电力系统同调群等值发电机功角变化，预测其变化趋势并判断是否会发生电网稳定事故，并利用多个仿真算例进行验证，为调度员提前采取控制措施提供参考。.