大信号扰动下基于切换序列的阻抗源网络动态建模与优化控制研究

The characteristics of strong nonlinearity, time-variation, and complicated operating modes, which inherented in the impedance network, result in small-signal-linearization-based modeling and control methods not appropriate to describe accurrately dynamic features and to control optimally dynamic behaviors for the impedance network underwent large-signal perturbations. For solveing such a problem, switched sequences are lead into the dipicting of state trajectories of the impedance network, thus the movements property with hop shifting for discrete positions on the whole while gradual varying for continous motions locally is successfully characterized. With the help of swithced sequences, every linear subsystems of the impedance network are decided their orders and durations. After that, a periodic switched linear model for the impedance network is found so that dynamic features under large-signal perturbations are achived to describe accurately. Refering to the concept of the state space, a basic theory system for the switched-sequences-based impedance netowork under large-signal perturbations is set up in terms of stability, controllability, reachability, observability, and output controllability. Five optimal switched sequences suitable for large-signal perturbations, such as norms, convergence paths, convergence distances, convergence directions and over-all properties, are constructed to act on the convergence process of state trajectories. Therefore, dynamic behavirous of the impedance network can be controlled optimally. With the completeness of aforementioned works, the difficult problem of dynamic modeling and optimal control for the impedance network underwent large-signal perturbations may be solved by this project fund.

阻抗源网络的强非线性、时变性及运行模态复杂多变性的特点，导致现有基于小信号线性化的建模与控制方法，无法精准描述大信号扰动下阻抗源网络的动态特性，难以优化控制大信号扰动下阻抗源网络的动态行为。本项目研究(1)引入切换序列刻画大信号扰动下阻抗源网络的状态轨迹，表征整体上离散位置跳跃迁移、局部上连续运行渐进变化的运动特征；(2)借助切换序列决定阻抗源网络各个线性子系统的作用顺序和持续时间，构建阻抗源网络周期性切换线性系统模型，精准描述大信号扰动下的动态特性；(3)借鉴状态空间的概念，着眼于稳定性，状态能控性、能达性、能观性，输出能控性等基本控制特性，创建大信号扰动下阻抗源网络基于切换序列的理论体系；(4)构造大信号扰动下基于范数、收敛路径、收敛距离、收敛方向、综合性能的优化切换序列，通过状态轨迹的收敛过程，优化控制阻抗源网络的动态行为。本项目的研究有望解决大信号扰动下阻抗源网络的建模与控制难题。

Z源逆变器在可再生能源发电中有着广阔的应用前景，但其核心构成部件阻抗源网络却呈现出强非线性、时变性及运行模态复杂多变性的特点，故而导致现有基于小信号线性化的建模与控制方法，难以胜任大信号扰动下对阻抗源网络动态特性进行精准描述、进而优化控制其动态行为的要求。为此，本项目提出了一种基于切换序列的阻抗源网络动态建模与优化控制方案。首先，研究了基于“切换序列”的动态建模方法，给出了切换线性系统以及切换序列的定义，解释了切换序列的物理意义，并提供了基于切换序列建立电力电子系统动态模型的基本步骤。其次，建立了阻抗源网络的周期性切换线性系统模型，并采用多项式插值法，将模型中的连续变量和离散变量予以了显性表示，据此解释了阻抗源网络周期性切换线性系统模型的一般意义。接着，构建了阻抗源网络的基础控制理论体系，涉及阻抗源网络稳定性的定义，稳定性的判断依据以及镇定方法；阻抗源网络状态能控、能达、能观以及输出能控的定义，一个开关周期之后和多个开关周期的状态能控、能达、能观以及输出能控的充分必要条件。最后，提供了基于范数、收敛路径、收敛距离、收敛方向以及综合性能优化的切换序列，从而使得阻抗源网络运行于优化状态。本项目的研究有望解决大信号扰动下阻抗源网络的建模与控制难题；更为重要的是，基于“切换序列”来建模和控制的思路及方法还可以为其它类型的电力电子系统动态建模与优化控制提供理论保证，因而具有广泛的应用价值。