CPS: Medium: Coupled cAscade Modeling, Prevention, and Recovery (CAMPR): When Graph Theory meets Trajectory Sensitivity

拟议的研究集中在电能网络物理系统(CPS)中的连锁故障，CPS是我国的关键基础设施。连锁故障是电网停电的主要原因，其中一个或几个部件的故障会导致互联系统的广泛故障。这种故障的机制非常复杂，因为它涉及电网的物理层(例如发电机、传输线等)。以及网络层(例如，通信和控制元件)。这是一个需要调查的非常重要的问题，因为连锁故障可能会给我们的经济造成数十亿美元的损失。该项目着眼于控制电能CPS中的连锁故障。这项拟议的研究有两个紧密结合的推力领域。推力1旨在准确了解连锁故障机理及其预防，而推力2侧重于在故障位置不确定的情况下进行停电恢复。利用轨道敏感度理论和图论建立了对能量CPS中连锁故障的基本认识，可应用于物理系统本质上是动态的、物理系统和网络系统中的故障传播是耦合的其他CPSS。拟议的预防性控制战略可以保护关键基础设施免受大规模故障的影响，并促进更高的恢复能力，而拟议的恢复战略适用于级联、自然灾害或其他事件造成的停电后，这将减少关键基础设施的停机时间。为支持扩大妇女参与计算机活动的倡议，拟议的研究将纳入宾夕法尼亚州立大学电子工程学院提供的为期一周的夏令营。2019年夏令营将在为期一周的时间里向高中女孩介绍这项研究，然后将在2020年和2021年提供侧重于这项研究主题的课程的夏令营。拟议的研究有两个关键目标(A)发展对连锁故障机制及其预防的准确理解，以及(B)在故障地点和预算限制的不确定性下制定停电后的恢复计划。文献中用于研究串级传播的电网准稳态(QSS)模型对停电的后期阶段产生不准确的结果，而完全动态模型不适用于大规模统计分析。为了解决这一问题，提出了一种“时间混合”模型和“时空混合”模型，分别在系统级和部件级采用轨迹灵敏度理论量化网格的应力，并适当地从QSS模型切换到动态模型。其次，针对相互依赖的电网和通信系统建立了统一的基于图的模型，该模型考虑了传统的监控和数据采集(SCADA)系统以及现代广域监控、保护和控制(WAMPAC)系统的几个特点，以及它们为CPS提供的可观测性和可控性。在此基础上，提出了一种稳定约束的串级预防补救行动方案。最后，在存在预算限制和故障不确定性的情况下，提出了一种利用混合电网模型和统一通信网络模型进行渐进评估和恢复的新方法。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The proposed research focuses on cascading failures in electrical energy cyber-physical systems (CPS), which is a critical infrastructure of our nation. Cascading failures, where the failure of one or few components causes a wide-spread failure of the interconnected system, is a major cause of blackouts in power grids. The mechanism of such failures is highly complex as it involves the physical layer of the grid (e.g. generators, transmission lines, etc.) and the cyber layer (e.g. communication and control elements) in a coupled manner. This is a very important problem to investigate as cascading failures can cost our economy billions of dollars. This project takes a holistic view at taming cascading failures in electrical energy CPS. The proposed research has two tightly coupled thrust areas. Thrust 1 aims at an accurate understanding of the cascading failure mechanism and its prevention, while Thrust 2 focuses on recovery following blackouts under uncertainty of failure locations. Theory of trajectory sensitivity and graph theory are leveraged to develop a fundamental understanding of cascading failures in energy CPS, which can be applied to other CPSs where the physical system is dynamic in nature and the failure propagation in the physical system and the cyber system are coupled. The proposed preventive control strategy can protect critical infrastructures from large-scale failures and facilitate higher resiliency, whereas the proposed recovery strategy is applicable in the aftermath of a blackout caused by cascades, natural disasters, or other events, which will reduce downtime of the critical infrastructure. In support of the Broadening Participation in Computing initiative among women, the proposed research will be integrated into the one-week summer camps offered by the School of EECS at Penn State. Presentations about this research will be given to high school girls over the course of one week in the 2019 camps, and then camps focused on curriculum on the topic of this research will be offered in 2020 and 2021.The proposed research has two key objectives (a) develop an accurate understanding of the cascading failure mechanism and its prevention, and (b) develop a recovery plan following blackouts under uncertainty of failure locations and budget constraints. The quasi-steady-state (QSS) model of power grid used in literature for studying cascade propagation produces inaccurate results towards the later stages of blackouts, whereas a fully dynamic model is impractical for large-scale statistical analyses. To solve this, a 'temporally hybrid' and a 'spatio-temporally hybrid' model are proposed, which quantify the stress of the grid at the systems level and the component level, respectively, using trajectory sensitivity theory, and appropriately switch from the QSS to the dynamic model. Next, a unified graph-based model for interdependent power grid and communication systems is developed, which takes into account several special features of the legacy Supervisory Control and Data Acquisition (SCADA) system along with the modern Wide-Area Monitoring, Protection, and Controls (WAMPAC) system, and the observability and controllability they provide for the CPS. Furthermore, a stability-constrained remedial action scheme for cascade prevention is proposed. Finally, a new approach for progressive assessment and recovery, which leverages the hybrid power grid models and the unified communication network model, is proposed in the presence of budget constraints and failure uncertainties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.