(1990). ENERGY FUNCTION ANALYSIS FOR POWER SYSTEM STABILITY. Electric Machines & Power Systems: Vol. 18, No. 2, pp. 209-210.

Energy function analysis for power system stability

Annual Energy Outlook

With rapid advances in sensor, computer, and communication networks, modern power systems have become complicated cyber-physical systems. Assessing and enhancing cyber-physical system security is, therefore, of utmost importance for the future electricity grid. In a successful false data injection attack (FDIA), an attacker compromises measurements from grid sensors in such a way that undetected errors are introduced into estimates of state variables such as bus voltage angles and magnitudes. In evading detection by commonly employed residue-based bad data detection tests, FDIAs are capable of severely threatening power system security. Since the first published research on FDIAs in 2009, research into FDIA-based cyber-attacks has been extensive. This paper gives a comprehensive review of state-of-the-art in FDIAs against modern power systems. This paper first summarizes the theoretical basis of FDIAs, and then discusses both the physical and the economic impacts of a successful FDIA. This paper presents the basic defense strategies against FDIAs and discusses some potential future research directions in this field.

A Review of False Data Injection Attacks Against Modern Power Systems

The Future of the Internet and How to Stop It Jonathan Zittrain. New Haven: Yale University Press, 2008. 342 pages. $30.00.Jonathan Zittrain's book, The Future of the Internet and How to Stop It, discusses the tension between generativity, the "capacity to produce unanticipated change through unfiltered contributions from a broad and varied audience" and the security problems inherent in today's personal computers and Internet system (70). This generativity, Zittrain argues, is the greatest strength of personal computers and the Internet and had led to great innovations, including creative software, peer-to-peer networking, blogs and content sites such as Wikipedia, and even the Internet itself. Yet this same generativity has also spawned security, legal, and social problems that may lead to the demise of personal computers and the Internet as they exist today (101). If we do not find solutions for these problems, Zittrain warns, we will be faced with government or corporate control of personal computers and the Internet, similar to current controls of cellular telephones and cable converter boxes, which will effectively shut down the innovations that personal computers and the Internet currently enable (245). Personal computers, according to Zittrain, will become nothing but appliances programmed by the manufacturer, capable only of limited tasks, and stripped of the tools and capabilities necessary for innovation.The first part of the book traces the history of personal computers, mainframes, proprietary servers, and the Internet. This section highlights how differences in technology and administration fostered generativity in personal computers and on the Internet and prohibited innovation on the mainframes and proprietary networks. Yet the innovations made possible by the generative nature of the Internet and personal computers also created its vulnerabilities: viruses, worms, malware, and spyware. Despite his obvious support of generativity, Zittrain admits that the current situation is "not sustainable" (43), but warns that the obvious solutions-such as limited functionality, governmental controls, and censorship-completely undermine the creativity made possible by personal computers and the Internet. The sec- ond part of the book defines generativity and explores its benefits and detriments. Here, Zittrain proposes that information technology functions best when generative, while admitting that we cannot ignore the problems caused by generativity (64), and warns equally of the dangers of controlled appliances: censorships, surveillance, forced legal compliance, and unannounced changes in machine functions. Chapter 6 in this section considers Wikikpedia as a self-regulating generative system that functions imperfectly but well. Part Three proposes technological, legal, and social solutions to the problems discussed earlier in the book.The Future of the Internet intertwines its analysis of current personal computer/Internet problems with current and historical examples from business, law, culture (Internet and otherwise), and technology. These examples, often worthwhile and interesting in and of themselves, underpin Zittrain's analysis rationally and support his conclusions. The examples show that the kind of sledgehammer solutions that Zittrain predicts are not merely possibilities or potentialities, but already have been and are being employed by various companies and governments. Perhaps best of all, Zittrain's use of these historical and current examples avoids the sensationalism often seen in other works that predict governmental and corporate control of options, behavior, and creativity. …

The Future of the Internet and How to Stop It

The accurately estimated state is of great importance for maintaining a stable running condition of power systems. To maintain the accuracy of the estimated state, bad data detection (BDD) is utilized by power systems to get rid of erroneous measurements due to meter failures or outside attacks. However, false data injection (FDI) attacks, as recently revealed, can circumvent BDD and insert any bias into the value of the estimated state. Continuous works on constructing and/or protecting power systems from such attacks have been done in recent years. This survey comprehensively overviews three major aspects: constructing FDI attacks; impacts of FDI attacks on electricity market; and defending against FDI attacks. Specifically, we first explore the problem of constructing FDI attacks, and further show their associated impacts on electricity market operations, from the adversary's point of view. Then, from the perspective of the system operator, we present countermeasures against FDI attacks. We also outline the future research directions and potential challenges based on the above overview, in the context of FDI attacks, impacts, and defense.

False Data Injection on State Estimation in Power Systems—Attacks, Impacts, and Defense: A Survey

This paper focuses on the role of networked microgrids as distributed systems for enhancing the power system resilience against extreme events. Resilience is an intrinsically complex property which requires deep understanding of microgrid operation in order to respond effectively in emergency conditions. The paper first introduces the definition and offers a generic framework for analyzing the power system resilience. The notion that large power systems can achieve a higher level of resilience through the deployment of networked microgrids is discussed in detail. In particular, the management of networked microgrids for riding through extreme events is analyzed. In addition, the merits of advanced information and communication technologies (ICTs) in microgrid-based distributed systems that can support the power system resilience are presented. The paper also points out the challenges for expanding the role of distributed systems and concludes that networked microgrids in particular provide a universal solution for improving the resilience against extreme events in Smart Cities.

Networked Microgrids for Enhancing the Power System Resilience

This paper analyzes a coordinated cyber–physical attack on power systems, which could lead to undetectable line outages. Coordinated with physical attacks that cause line outages, the two-step cyberattacks comprising topology preserving and load redistribution attacks could mask and potentially exasperate outages to trigger cascading failures. These coordinated cyber–physical attacks are analyzed in a proposed bilevel model, which aims at identifying the most damaging and undetectable physical attacks constrained by attackers’ total budget. After being transformed into a mixed-integer linear programming problem, the proposed bilevel model is solved by a rigorous two-stage solution approach. This paper also discusses the relevant countermeasure strategies. The proposed model, the solution algorithm, and the effectiveness of countermeasures are examined by case studies based on the IEEE 14- and 118-bus test systems.

Bilevel Model for Analyzing Coordinated Cyber-Physical Attacks on Power Systems

A robust security-constrained unit commitment (robust SCUC) model is proposed in this paper to enhance the operational reliability of integrated electricity-natural gas system (IEGS) against possible transmission line outages. In this work, adjustable capability of natural gas contract is considered to avoid dramatic changes in real-time gas demand. Distributed natural gas storage is also included to smooth out power system demand curve and further improve operational efficiency at normal state and during contingencies. Nonlinear and nonconvex natural gas flow functions are relaxed into second-order cone (SOC) constraints, then the SOC-based column and constraint generation method is adopted to solve the proposed two-stage robust convex optimization problem. In this iterative method, the security-check subproblem feeds back worst case constraints to the first-stage master problem, until no violated scenarios can be detected. Simulations tested on 6-bus-6-node and 118-bus-10-node IEGS with natural gas storage show that the proposed storage model is effective in the robust SCUC solution for IEGS considering possible N − k contingencies with limited natural gas adjustments.

Robust Constrained Operation of Integrated Electricity-Natural Gas System Considering Distributed Natural Gas Storage

Blockchain for decentralized transactive energy management system in networked microgrids

A large-scale integrated energy system can represent several subsystems representing areas that are tied by electricity and natural gas networks. Accordingly, we propose a decentralized optimal energy flow (DOEF) calculation as compared with a centralized solution method. The proposed approach demonstrates the merits of the decentralized operation and control of a multi-area integrated electricity-natural gas system (IEGS), in terms of large-scale modeling requirements, faster computations, and data management for local sensitivity analyses. Using the proposed decentralized structure, the communication burden is relatively light as individual area operators in a multi-area IEGS will make optimal dispatch decisions independently and the corresponding information is shared with adjacent subsystems. The reformulation of the second-order cone (SOC) is proposed using advanced sequential cone programming (SCP) to handle the nonlinear steady-state natural gas flow, which provides a feasible solution with a high degree of computational efficiency. Furthermore, an iterative alternating direction method of multipliers (I-ADMM) is adopted to manage the nonconvexity of integer variables, which guarantees a satisfactory convergence performance. Case studies on three multi-area IEGS validate the effectiveness of the proposed model in a multi-area IEGS.

Zhiyi Li

Papers

Networked Microgrids for Enhancing the Power System Resilience

Bilevel Model for Analyzing Coordinated Cyber-Physical Attacks on Power Systems

Robust Constrained Operation of Integrated Electricity-Natural Gas System Considering Distributed Natural Gas Storage

Blockchain for decentralized transactive energy management system in networked microgrids

Decentralized Optimization of Multi-Area Electricity-Natural Gas Flows Based on Cone Reformulation