On the Definition of Cyber-Physical Resilience in Power Systems (1504.05916v2)

Abstract: In recent years, advanced sensors, intelligent automation, communication networks, and information technologies have been integrated into the electric grid to enhance its performance and efficiency. Integrating these new technologies has resulted in more interconnections and interdependencies between the physical and cyber components of the grid. Natural disasters and man-made perturbations have begun to threaten grid integrity more often. Urban infrastructure networks are highly reliant on the electric grid and consequently, the vulnerability of infrastructure networks to electric grid outages is becoming a major global concern. In order to minimize the economic, social, and political impacts of power system outages, the grid must be resilient. The concept of a power system cyber-physical resilience centers around maintaining system states at a stable level in the presence of disturbances. Resilience is a multidimensional property of the electric grid, it requires managing disturbances originating from physical component failures, cyber component malfunctions, and human attacks. In the electric grid community, there is not a clear and universally accepted definition of cyber-physical resilience. This paper focuses on the definition of resilience for the electric grid and reviews key concepts related to system resilience. This paper aims to advance the field not only by adding cyber-physical resilience concepts to power systems vocabulary, but also by proposing a new way of thinking about grid operation with unexpected disturbances and hazards and leveraging distributed energy resources.

• The paper introduces a novel resilience framework that shifts power systems from traditional risk assessment to dynamic recovery strategies.
• The paper quantifies vulnerabilities by linking severe weather to nearly 90% of U.S. customer outages and exposing SCADA system risks.
• The paper advocates for integrating DER-based microgrids and advanced ICT to bolster defense against interconnected cyber and physical threats.

An Expert Review of Cyber-Physical Resilience in Power Systems

This paper addresses an increasingly critical topic in the domain of power systems: the concept of cyber-physical resilience. Amid a rapidly evolving technological landscape, where enhanced sensors and intelligent automation pervade electric grids, the integration of these technologies is forming intricate interdependencies between physical and cyber components. These interconnections necessitate a re-evaluation of grid resilience, especially as natural and anthropogenic perturbations challenge grid integrity.

The authors delineate the essential components of resilience within power grids and articulate a framework for understanding these challenges. By dissecting the "pillars of resilience," the paper attempts to shift the conversation from traditional risk assessment approaches—focused on likelihood and consequences of disruptive events—to resilience, which is more concerned with the ability to adapt and recover from such events, emphasizing the temporal dimension of such disturbances.

Key sections of the paper highlight various dimensions of power system vulnerabilities, including physical, cyber, and cyber-physical vulnerabilities. The authors underscore the current inadequacies in distribution networks concerning system observability, monitoring, and overall resilience against disruptions. Notably, the introduction of distributed energy resources (DER) within microgrids is presented as a potential mitigative strategy—a forward-thinking approach suggesting a more localized, modular, and decentralized grid operation.

This paper's illustrative case paper of DER in microgrids propounds a tangible application for enhancing resilience. Assistive strategies like grid partitioning into microgrids, embedding distributed intelligence, and adopting advanced ICT frameworks indicate a shift towards a reactive and adaptive grid infrastructure.

The analysis of vulnerabilities is well-rounded, extending from the overwhelming risks of severe weather causing physical damage (contributing to approximately 90% of customer outages in the U.S.) to potential cyber intrusions. These represent a dual challenge: securing physical infrastructure and strengthening cyber defenses. The paper discusses the susceptibility of supervisory control and data acquisition (SCADA) systems to these cyber threats, illustrating the cyber-physical interconnectedness and the challenges it presents for maintaining system integrity and service availability.

Furthermore, the authors distinguish between resilience and robustness, emphasizing that the former hinges on adaptability and the capacity for rapid recovery post-disturbances, while the latter pertains to inherent structural strength. Acknowledging that robustness may paradoxically lead to fragility under unforeseen threats, the discussion advocates for a resilience-oriented strategy that prioritizes system adaptability and quick restoration abilities.

In advancing the dialogue beyond traditional constructs of reliability and stability, the paper sets the foundation for future work in defining and measuring resilience quantitatively. It proposes future research directions focusing on cyber-physical resilience metrics, informed by probabilistic time-domain frameworks to assess damage likelihood more systematically.

Ultimately, the paper suggests that an effective resilience strategy requires both technological advancements and a conceptual shift. The traditional power system operations centered around robustness must evolve to incorporate resilient operational strategies that account for the dynamic and interconnected nature of modern power grids. This research contributes substantively to a nascent dialogue that urgently needs to progress in an era marked by both sophisticated cyber threats and evolving grid infrastructure.