CAREER: Integrated Research and Education in Nonlinear Modal Decoupling and Control for Resilient Interconnected Power Systems

传统的电力系统稳定性分类已经在实践中工作了几十年，但将不再是足够的互联电力系统的高渗透率的间歇性可再生能源，因为一些预定义的稳定性类别，如小信号稳定性和暂态稳定性不再是分开的，在现实生活中的电力系统不稳定性。实际上，从系统的角度来看，电力系统的稳定性评估是一个单一的非线性动态问题。然而，一个主要的技术差距在于目前缺乏快速，准确的稳定性分析工具，复杂的，互联的，非线性系统，如电力系统。本计画的目的是在了解、解耦与控制非线性模态动态的基础上，建立电力系统稳定性分析与控制的新方法。该项目的成果预计将对电力行业和研究界产生广泛影响。所提出的新方法建立的基本理论可以推广到其他大规模动态系统。该项目将教育不同层次的学生理解互联电力系统固有的模态动力学和非线性，并培养下一代科学家和工程师，将更多的非线性思维带入研究，设计和运营未来容纳更多可再生能源的智能电网。该项目的研究目标包括：（1）深入理解与系统状态的不变流形相关联的互联电力系统的非线性模态动力学，（2）建立了一种通过非线性模态解耦和控制来改善电力系统稳定性的新方法;（3）将这种新方法归结为简单的方法，如实用的电力系统非线性模态分析和稳定性监测工具。具体而言，本项目将把小干扰稳定分析中的线性模态概念扩展到电力系统全局稳定分析的非线性模态，并基于规范形方法对电力系统数学模型进行结构化分解，为非线性模态的自然解耦和受控解耦奠定理论基础，提出了基于非线性模态能量跟踪和控制的在线稳定性评估和控制算法。这种新的方法可能是电力系统稳定领域的变革，因为理解电力系统的非线性模式的想法在这些领域还没有得到足够的重视，有显着的简单性与稳定性分析集中在一个或几个模式相比，原来的高维系统模型。因此，本项目的研究可能会指出一个新的途径，比实时更快的稳定性评估和控制补充传统的计算机仿真为基础的方法。

The conventional classification of power system stability has worked for decades in practice but will no longer be adequate on interconnected power systems with high penetration of intermittent renewable resources because some predefined stability categories such as small-signal stability and transient stability are no longer separate in real-life power system instabilities. In fact, stability assessment for a power system is a single nonlinear dynamic problem from the system point of view. However, a major technical gap lies in the current lack of fast, accurate stability analysis tools for complex, interconnected, nonlinear systems like power systems. This project aims at reducing that gap by establishing a new methodology for power system stability analysis and control based on understanding, decoupling and control of nonlinear modal dynamics. The outcomes of the project are expected to create broad impacts on both the power industry and research community. Fundamental theories established with the proposed new methodology can be generalized for other large-scale dynamic systems. The project will educate students at various levels in comprehending modal dynamics and nonlinearities inherent in interconnected power systems and train next-generation scientists and engineers to bring more nonlinear thinking to researching, designing and operating the future smart grid accommodating more renewable energy.The research goals of the project include: (1) acquiring an in-depth understanding in nonlinear modal dynamics of an interconnected power system that are associated with invariant manifolds of the system state, (2) establishing a new approach for improving power system stability by nonlinear modal decoupling and control, and (3) boiling the new approach down to simple recipes such as practical tools for nonlinear modal analysis and stability monitoring of power systems. More specifically, the project will extend the concept of linear normal modes in small-signal stability analysis to nonlinear normal modes of power systems for global stability analysis, establish a theoretical foundation for natural decoupling and controlled decoupling of nonlinear normal modes based on the normal form method to structurally decompose the mathematical model of a power system, and propose innovative online stability assessment and control algorithms based on tracking and control of modal energy with nonlinear normal modes. This new methodology could be transformative to power system stability areas since the idea of understanding the nonlinear modes with power systems has not received enough attention in those areas and there is significant simplicity with stability analysis focusing on one or few modes compared to the original high-dimensional system model. Thus, the research of this project may point to a new avenue for faster-than-real-time stability assessment and control complementing the traditional computer simulation based approach.