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方法已经在实践中使用了几十年，但由于在实际的电力系统不稳定中，小信号稳定和暂态稳定等一些预定义的稳定类别不再是分开的，因此对于间歇性可再生资源渗透率高的互联电力系统来说，传统的电力系统稳定性分类方法将不再适用。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，用于复杂的，互联的，非线性系统，如电力系统。本项目旨在通过建立一种基于非线性模态动力学的理解、解耦和控制的电力系统稳定性分析和控制的新方法来缩小这一差距。该项目的成果预计将对电力行业和研究界产生广泛的影响。用新方法建立的基本理论可以推广到其他大尺度动态系统。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、设计和运营未来的智能电网，以适应更多的可再生能源。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态动力学；(2)建立一种通过非线性模态解耦和控制提高电力系统稳定性的新方法；(3)将新方法简化为简单的方法，如用于电力系统非线性模态分析和稳定性监测的实用工具。具体而言，本项目将把小信号稳定性分析中的线性正态模态概念推广到电力系统的非线性正态模态进行全局稳定性分析，建立基于范式方法的非线性正态模态自然解耦和控制解耦的理论基础，对电力系统的数学模型进行结构分解；提出了基于非线性正态模态能量跟踪与控制的新型在线稳定性评估与控制算法。这种新方法可能对电力系统稳定领域具有革命性意义，因为在这些领域中，理解电力系统非线性模态的思想尚未得到足够的重视，而且与原始的高维系统模型相比，只关注一个或几个模态的稳定性分析非常简单。因此，该项目的研究可能为快速进行稳定性评估和控制提供了一条新的途径，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.