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运行了几十年，但对于间歇性可再生资源渗透率较高的互联电力系统来说，已经不再适用，因为一些预定义的稳定类别，如小干扰稳定和暂态稳定，在实际电力系统不稳定中不再是分开的。从系统的角度来看，电力系统的稳定评估实际上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、准确的稳定分析工具来分析像电力系统这样的复杂、相互关联的非线性系统。该项目旨在通过建立一种新的电力系统稳定分析和控制方法来缩小这一差距，该方法基于对非线性模态动力学的理解、解耦和控制。该项目的结果预计将对电力行业和研究界产生广泛影响。用所提出的新方法建立的基本理论可推广到其他大系统。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式动力学和非线性，并培训下一代科学家和工程师将更多的非线性思维带入未来容纳更多可再生能源的智能电网的研究、设计和运行。该项目的研究目标包括：(1)深入了解与系统状态不变流形相关的互联电力系统的非线性模式动力学，(2)建立一种通过非线性模式解耦和控制来提高电力系统稳定性的新方法，以及(3)将新方法归结为简单的配方，例如用于电力系统非线性模式分析和稳定性监测的实用工具。具体地说，该项目将小干扰稳定性分析中线性正态模式的概念推广到电力系统全局稳定性分析中的非线性正态模式，为基于规范形法对电力系统数学模型进行结构分解的非线性正态模式的自然解耦和受控解耦奠定了理论基础，并提出了基于非线性正态模式的模式能量跟踪和控制的在线稳定评估和控制算法。这种新的方法可能会对电力系统稳定领域产生变革，因为理解电力系统非线性模式的思想在这些领域没有得到足够的重视，而且与原始的高维系统模型相比，关注一个或几个模式的稳定性分析有很大的简单性。因此，该项目的研究可能为快速实时稳定评估和控制开辟一条新的途径，以补充传统的基于计算机仿真的方法。

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.