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Smart Grid Security


The primary value of published research in smart grid technologies—the use of cyber-physical systems to coordinate the generation, transmission, and use of electrical power and its sources—is because of its strategic importance and the consequences of intrusion. Smart grid is of particular importance to the Science of Security and its problems embrace several of the hard problems, notably resiliency and metrics.  The work cited here was published in 2015 and was recovered from IEEE.


Law, Y.W.; Alpcan, T.; Palaniswami, M., "Security Games for Risk Minimization in Automatic Generation Control," Power Systems, IEEE Transactions on, vol. 30, no. 1, pp. 223, 232, Jan. 2015. doi: 10.1109/TPWRS.2014.2326403 Abstract: The power grid is a critical infrastructure that must be protected against potential threats. While modern technologies at the center of the ongoing smart grid evolution increase its operational efficiency, they also make it more susceptible to malicious attacks such as false data injection to electronic monitoring systems. This paper presents a game-theoretic approach to smart grid security by combining quantitative risk management techniques with decision making on protective measures. The consequences of data injection attacks are quantified using a risk assessment process where the well-known conditional value-at-risk (CVaR) measure provides an estimate of the defender's loss due to load shed in simulated scenarios. The calculated risks are then incorporated into a stochastic security game model as input parameters. The decisions on defensive measures are obtained by solving the game using dynamic programming techniques which take into account resource constraints. Thus, the formulated security game provides an analytical framework for choosing the best response strategies against attackers and minimizing potential risks. The theoretical results obtained are demonstrated through numerical examples. Simulation results show that different risk measures lead to different defense strategies, but the CVaR measure prioritizes high-loss tail events.
Keywords: decision making; load shedding; power generation control; power system protection; smart power grids; stochastic games; automatic generation control; conditional value-at-risk measure; data injection attacks; decision making; defensive measures; dynamic programming techniques; electronic monitoring systems; false data injection; game-theoretic approach; high-loss tail events; load shed; malicious attacks; operational efficiency; power grid; protective measures; quantitative risk management techniques; resource constraints; response strategies; risk assessment process; risk minimization; security games; smart grid evolution; smart grid security; stochastic security game model; Automatic generation control; Frequency control; Game theory; Games; Risk management; Security; Smart grids; Automatic generation control; cyber-physical system security; security games; smart grid (ID#: 15-4821)


Zhuo Lu; Wenye Wang; Wang, C., "Camouflage Traffic: Minimizing Message Delay for Smart Grid Applications under Jamming," Dependable and Secure Computing, IEEE Transactions on, vol. 12, no. 1, pp. 31, 44, Jan.-Feb. 1 2015. doi: 10.1109/TDSC.2014.2316795 Abstract: Smart grid is a cyber-physical system that integrates power infrastructures with information technologies. To facilitate efficient information exchange, wireless networks have been proposed to be widely used in the smart grid. However, the jamming attack that constantly broadcasts radio interference is a primary security threat to prevent the deployment of wireless networks in the smart grid. Hence, spread spectrum systems, which provide jamming resilience via multiple frequency and code channels, must be adapted to the smart grid for secure wireless communications, while at the same time providing latency guarantee for control messages. An open question is how to minimize message delay for timely smart grid communication under any potential jamming attack. To address this issue, we provide a paradigm shift from the case-by-case methodology, which is widely used in existing works to investigate well-adopted attack models, to the worst-case methodology, which offers delay performance guarantee for smart grid applications under any attack. We first define a generic jamming process that characterizes a wide range of existing attack models. Then, we show that in all strategies under the generic process, the worst-case message delay is a U-shaped function of network traffic load. This indicates that, interestingly, increasing a fair amount of traffic can in fact improve the worst-case delay performance. As a result, we demonstrate a lightweight yet promising system, transmitting adaptive camouflage traffic (TACT), to combat jamming attacks. TACT minimizes the message delay by generating extra traffic called camouflage to balance the network load at the optimum. Experiments show that TACT can decrease the probability that a message is not delivered on time in order of magnitude.
Keywords: jamming; power system security; probability; radio networks; radiofrequency interference; smart power grids; telecommunication security; telecommunication traffic; TACT; U-shaped function; camouflage traffic; code channel; control messages; cyber-physical system; delay performance guarantee; existing attack model; generic jamming process; information exchange; information technologies; jamming attack; jamming resilience; latency guarantee; message delay minimization; multiple-frequency channel; network load balance; network traffic load; power infrastructures; primary security threat; probability; radio interference broadcast; smart grid application; smart grid communication; spread spectrum systems; transmitting adaptive camouflage traffic; well-adopted attack model; wireless communication security; wireless network deployment; worst-case message delay; Communication system security; Delays; Power distribution; Receivers; Smart grids; Wireless networks; Smart grid; jamming attacks; message delay; performance modeling; wireless applications; worst-case analysis (ID#: 15-4822)


Martínez, E.; De La O Serna, J., "Smart grids Part 1: Instrumentation Challenges," Instrumentation & Measurement Magazine, IEEE, vol. 18, no. 1, pp. 6, 9, February 2015. doi: 10.1109/MIM.2015.7016673 Abstract: In general, a smart grid is a modernized electrical grid that uses digital technology for measurement, control, and protection functions to ensure a network security. It tries to solve the problem of weather-dependant fluctuations of renewable energy power supplies (e.g. wind turbines, or photo-voltaic systems) when they are connected to an actual power system. In two papers in this issue, we present some of the challenges raised by Smart Grids in instrumentation and measurement applications, putting emphasis on synchrophasor estimation. In this part 1 article, we describe the problem of identifying a normal condition from a fault condition and between a fault condition and an oscillation using phasor estimations in protective relays. In "Synchrophasor Measurement Challenges in Smart Grids," we discuss a novel synchrophasor-estimation algorithm that improves the accuracy of the estimates under oscillations conditions and serves to identify electromechanical modes in Smart Grids. This algorithm ameliorates protection as well as measurement applications in smart grids.
Keywords: phasor measurement; power supplies to apparatus; power system faults; power system protection; power system security; relay protection; renewable energy sources; smart power grids; ameliorates protection; digital technology; electrical grid; electromechanical modes iden-; fault condition; instrumentation application; network security; oscillations conditions; protective relay; renewable energy power supply; smart grid; synchrophasor estimation; weather-dependent fluctuation; Circuit faults; Oscillators; Phasor measurement units; Power system stability; Power system transients; Protective relaying; Smart grids (ID#: 15-4823)


Yu, W.; Xue, Y.; Luo, J.; Ni, M.; Tong, H.; Huang, T., "An UHV Grid Security and Stability Defense System: Considering the Risk of Power System Communication," Smart Grid, IEEE Transactions on, vol. PP, no.99, pp. 1, 1, 5 February 2015. doi: 10.1109/TSG.2015.2392100 Abstract: An ultra high voltage (UHV) ac and dc interconnection will become the foundation of China's future smart grid. Due to the wide spread of interconnected regions, the distance between control stations will increase dramatically. Therefore, the communication {system's} reliability and real-time performance will become increasingly crucial. However, failures of the communication {system}, such as interruptions, latency, and bit error, are inevitable. This paper uses the UHV grid security and stability defense system (SSDS) as an example to analyze its requirements for communication and the impact of communication failure on the system's performance. The effect of communication latency on the power system's stability is analyzed quantitatively and qualitatively. Based on this analysis, a framework of an UHV grid SSDS considering the risk of the communication system is proposed. A preliminary power system and communication system co-simulation tool is developed to perform a case study. The case study demonstrates that communication latency in the UHV grid changes the control strategy's effectiveness due to a delay in executing the control strategy. Furthermore, communication latency will negatively affect the power grid's stability.
Keywords: Electromagnetics; Generators; Power system stability; Real-time systems; Stability criteria; Synchronous digital hierarchy; Communication interruption; communication latency; power system and communication system co-simulation; security and stability defense system (SSDS);stability control (ID#: 15-4824)


Feng Diao; Fangguo Zhang; Xiangguo Cheng, "A Privacy-Preserving Smart Metering Scheme Using Linkable Anonymous Credential," Smart Grid, IEEE Transactions on, vol. 6, no. 1, pp. 461, 467, Jan. 2015. doi: 10.1109/TSG.2014.2358225 Abstract: Smart grid, as the next power grid, can efficiently monitor, predicate, and control energy generation/consumption by using the real-time users' electricity information. However, the fine-grained user energy consumption information may reveal the private information of the user. In this paper, we construct a linkable anonymous credential protocol based on Camenisch-Lysyanskaya (CL) signature. Then, we propose a privacy preserving smart metering scheme based on the new linkable anonymous credential. In addition to providing privacy protection for the user, our protocol also has the security properties of message authentication and traceability of fault smart metering. And there are some other useful features in our protocol, such as no need of trust-third party, dynamic users' enrollment and revocation, and complex statistical analysis of the energy use information. The computation cost and communication overhead of our scheme is O(1), which is independent of the user number. The simulation results show that our scheme is efficient.
Keywords: protocols; smart meters; smart power grids; Camenisch-Lysyanskaya signature; energy consumption; energy generation; fault smart metering; linkable anonymous credential; linkable anonymous credential protocol; message authentication; power grid; privacy protection; privacy-preserving smart metering scheme; protocol; security properties; smart grid; traceability; Data privacy; Electricity; Privacy; Protocols; Security; Smart grids; Statistical analysis; Anonymous credential; authentication; privacy; smart metering; traceability (ID#: 15-4825)


Chen, H.; Xuan, P.; Wang, Y.; Tan, K.; Jin, X., "Key Technologies for Integration of Multitype Renewable Energy Sources-Research on Multi-Timeframe Robust Scheduling/Dispatch," Smart Grid, IEEE Transactions on, vol. PP, no. 99, pp. 1, 1, 26 January 2015.  doi: 10.1109/TSG.2015.2388756 Abstract: Large-scale integration of multitype renewable energy (RE) sources (intermittent energy sources) has become an important feature in smart grid development all over the world. It is internationally recognized that the island (or weak-tie connected) power grids are the best platforms for intermittent energy integration test and demonstration because of their abundant RE resources, scarcity of conventional energy, and technical difficulty with accommodation of intermittent energy. The ongoing research on Hainan (the second biggest island in China) power grid will achieve a comprehensive breakthrough in power grid planning, analysis, scheduling, operation, relay protection, security control, disaster prevention, and other key areas in multitype RE source integration. To be specific, this paper focuses on the key part of the research project-optimal scheduling and complementary operation and a new framework of multitime-frame robust scheduling/dispatch system is first proposed, which is different from most other robust approaches and lays special emphasis on the engineering characteristics of power system operation. Simulation results based on the real data of Hainan power grid show that the approach presented is effective and will be put into online operation in the near future.
Keywords: Optimal scheduling; Power grids; Robustness; Uncertainty; Wind forecasting; Wind power generation; Intermittent energy source; island power grid; optimal scheduling/dispatch; robustness; smart grids (ID#: 15-4826)


Amin, S.; Schwartz, G.A.; Cardenas, A.A.; Sastry, S.S., "Game-Theoretic Models of Electricity Theft Detection in Smart Utility Networks: Providing New Capabilities with Advanced Metering Infrastructure," Control Systems, IEEE, vol.35, no.1, pp.66, 81, Feb. 2015. doi: 10.1109/MCS.2014.2364711 Abstract: The smart grid refers to the modernization of the power grid infrastructure with new technologies, enabling a more intelligently networked automated system with the goal of improving efficiency, reliability, and security, while providing more transparency and choices to electricity customers. A key technology being widely deployed on the consumption side of the grid is advanced metering infrastructure (AMI).
Keywords: game theory; power meters; power system reliability; power system security; smart power grids; AMI; advanced metering infrastructure; electricity customers; electricity theft detection; game theoretic models; power grid infrastructure; smart grid; smart utility networks; Computer security; Electricity supply industry; Investment; Power distribution; Power grids; Power system reliability; Schedules; Smart meters (ID#: 15-4827)


Akkaya, K.; Rabieh, K.; Mahmoud, M.; Tonyali, S., "Customized Certificate Revocation Lists for IEEE 802.11s-Based Smart Grid AMI Networks," Smart Grid, IEEE Transactions on, vol.6, no.5, pp.2366-2374, September 2015. doi: 10.1109/TSG.2015.2390131 Abstract: Public-key cryptography (PKC) is widely used in smart grid (SG) communications to reduce the overhead of key management. However, PKC comes with its own problems in terms of certificate management. Specifically, certificate revocation lists (CRLs) need to be maintained and distributed to the smart meters (SMs) in order to ensure security of the communications. The size of CRLs may grow over time and eventually may introduce additional delay, bandwidth, and storage overhead when various applications are run on SG. In this paper, we propose novel algorithms for creating customized CRLs with reduced size for IEEE 802.11s-based advanced metering infrastructure (AMI) networks. Rather than maintaining a huge-size single CRL that introduces unnecessary search time and storage, the idea is to cluster/group SMs within the AMI network and create CRLs based on these groups. The grouping is mainly done in such a way that they bring together the SMs that will be very likely to communicate so that the CRLs will be kept local to that group. To this end, we propose two novel grouping algorithms. The first algorithm is a bottom-up approach, which is based on the existing routes from the SMs to the gateway. Since the SMs will be sending their data to the gateway through the nodes on the route, this forms a natural grouping. The second approach is a top-down recursive approach, which considers the minimum spanning tree of the network and then divides it into smaller subtrees. Via grouping, the length of the CRL for each SM and the corresponding distribution overhead can be reduced significantly. Simulation results have shown that our approach can maintain a balance between the size of the CRL and the number of signatures generated by CAs while guaranteeing security of the communications.
Keywords: IEEE 802.11 Standards; Logic gates; Relays; Security; Smart grids; Wireless communication; Certificate revocations; grouping schemes; public key cryptography; security; smart grid (ID#: 15-4828)


Chim, T.W.; Siu-Ming Yiu; Li, V.O.K.; Hui, L.C.K.; Jin Zhong, "PRGA: Privacy-Preserving Recording & Gateway-Assisted Authentication of Power Usage Information for Smart Grid," Dependable and Secure Computing, IEEE Transactions on, vol.12, no.1, pp. 85, 97, Jan.-Feb. 1 2015.  doi: 10.1109/TDSC.2014.2313861 Abstract: Smart grid network facilitates reliable and efficient power generation and transmission. The power system can adjust the amount of electricity generated based on power usage information submitted by end users. Sender authentication and user privacy preservation are two important security issues on this information flow. In this paper, we propose a scheme such that even the control center (power operator) does not know which user makes the requests of using more power or agreements of using less power until the power is actually used. At the end of each billing period (i.e., after electricity usage), the end user can prove to the power operator that it has really requested to use more power or agreed to use less power earlier. To reduce the total traffic volume in the communications network, our scheme allows gateway smart meters to help aggregate power usage information, and the power generators to determine the total amount of power that needs to be generated at different times. To reduce the impact of attacking traffic, our scheme allows gateway smart meters to help filter messages before they reach the control center. Through analysis and experiments, we show that our scheme is both effective and efficient.
Keywords: data privacy; internetworking; message authentication; power engineering computing; smart meters; smart power grids; PRGA; billing period; communications network; gateway smart meters; power operator; power usage information; privacy-preserving recording & gateway-assisted authentication; smart grid; total traffic volume reduction; Electricity supply industry; Encryption; Logic gates; Power generation; Power transmission; Smart grids; Substations; Smart grid network; authentication; bloom filter;commitment; homomorphic encryption; privacy preserving (ID#: 15-4829)


Sun, H.; Zhao, F.; Wang, H.; Wang, K.; Jiang, W.; Guo, Q.; Zhang, B.; Wehenkel, L., "Automatic Learning of Fine Operating Rules for Online Power System Security Control," Neural Networks and Learning Systems, IEEE Transactions on, vol. PP, no. 99, pp. 1,1,  9 February 2015.  doi: 10.1109/TNNLS.2015.2390621 Abstract: Fine operating rules for security control and an automatic system for their online discovery were developed to adapt to the development of smart grids. The automatic system uses the real-time system state to determine critical flowgates, and then a continuation power flow-based security analysis is used to compute the initial transfer capability of critical flowgates. Next, the system applies the Monte Carlo simulations to expected short-term operating condition changes, feature selection, and a linear least squares fitting of the fine operating rules. The proposed system was validated both on an academic test system and on a provincial power system in China. The results indicated that the derived rules provide accuracy and good interpretability and are suitable for real-time power system security control. The use of high-performance computing systems enables these fine operating rules to be refreshed online every 15 min.
Keywords: Learning systems; Power system security; Power transmission lines; Real-time systems; Substations; Automatic learning; critical flowgate; knowledge discovery; online security analysis; smart grid; total transfer capability (ID#: 15-4830)


Liu, X.; Bao, Z.; Lu, D.; Li, Z., "Modeling of Local False Data Injection Attacks With Reduced Network Information," Smart Grid, IEEE Transactions on, vol.6, no.4, pp.1686-1696, July 2015. doi: 10.1109/TSG.2015.2394358 Abstract: Modern power grids are becoming more prone to cyberattacks. Even worse, an attacker without the full topology and parameter information of a power grid can still execute a false data injection attack without being detected by the state estimator. This paper proposes an efficient strategy for determining the optimal attacking region that requires reduced network information. The effectiveness of the proposed algorithm is verified through extensive simulations. This paper introduces a new front in the study of smart grid cyber security: determination of a feasible attacking region by obtaining less network information. This paper is also essential and significant for finding effective protection strategies against false data injection attacks based on the deep understanding of the mechanisms and strategies of the attacks.
Keywords: Data models; Generators; Jacobian matrices; Network topology; Power grids; Topology; Vectors; False data injection attacks; incomplete information; local load redistribution; optimal attacking strategy; power systems (ID#: 15-4831)


Jun Yan; Yufei Tang; Haibo He; Yan Sun, "Cascading Failure Analysis With DC Power Flow Model and Transient Stability Analysis," Power Systems, IEEE Transactions on, vol.30, no.1, pp.285, 297, Jan. 2015. doi: 10.1109/TPWRS.2014.2322082 Abstract: When the modern electrical infrastructure is undergoing a migration to the Smart Grid, vulnerability and security concerns have also been raised regarding the cascading failure threats in this interconnected transmission system with complex communication and control challenge. The DC power flow-based model has been a popular model to study the cascading failure problem due to its efficiency, simplicity and scalability in simulations of such failures. However, due to the complex nature of the power system and cascading failures, the underlying assumptions in DC power flow-based cascading failure simulators (CFS) may fail to hold during the development of cascading failures. This paper compares the validity of a typical DC power flow-based CFS in cascading failure analysis with a new numerical metric defined as the critical moment (CM). The adopted CFS is first implemented to simulate system behavior after initial contingencies and to evaluate the utility of DC-CFS in cascading failure analysis. Then the DC-CFS is compared against another classic, more precise power system stability methodology, i.e., the transient stability analysis (TSA). The CM is introduced with a case study to assess the utilization of these two models for cascading failure analysis. Comparative simulations on the IEEE 39-bus and 68-bus benchmark reveal important consistency and discrepancy between these two approaches. Some suggestions are provided for using these two models in the power grid cascading failure analysis.
Keywords: load flow; power system reliability; power system simulation; power system transient stability; DC power flow model; cascading failure analysis; critical moment; interconnected transmission system; power system stability; smart grid; transient stability analysis; Analytical models; Failure analysis; Mathematical model; Power system faults; Power system protection; Power system stability; Stability analysis; Cascading failure; DC power flow; contingency analysis; transient stability; vulnerability assessment (ID#: 15-4832)


Nachabe, L.; Girod-Genet, M.; El Hassan, B., "Unified Data Model for Wireless Sensor Network," Sensors Journal, IEEE, vol.15, no.7, pp.3657-3667, July 2015. doi: 10.1109/JSEN.2015.2393951 Abstract: The constant evolution of technology in terms of inexpensive and embedded wireless interfaces and powerful chipsets has led to the massive usage and deployment of Wireless Sensors Networks (WSNs). These networks are made of a growing number of small sensing devices and are used in multiple use cases such as home automation (e.g. Smart Buildings), energy management and Smart Grids, crisis management and security, e-Health, entertainment... Sensor devices, generally self-organized in clusters and domain-dedicated, are provided by an increasing number of manufacturers, which leads to interoperability problems (e.g. heterogeneous interfaces and/or grounding, heterogeneous descriptions, profiles, models...). Furthermore, data provided by these WSNs are very heterogeneous because they are coming from sensing nodes with various abilities (e.g. different sensing ranges, formats, coding schemes, etc.). In this paper, we propose a solution for handling WSNs’ heterogeneity, as well as easing interoperability management. The solution consists of a semantic open data model for sensor and sensor data generic description. This data model, designed for handling any kind of sensors/actuators and measured data (which is still not the case of existing WSNs data models), is fully detailed and formalized in an original ontology format called “MyOntoSens” and written using OWL 2 DL language. The proposed ontology has been implemented using Protégé 4.3, pre-validated with Pellet Reasoner, and is being standardized1. In addition, this original ontology has been pre-qualified through a runner’s exercise monitoring application, using in particular SPARQL query language, within a small WBAN platform comprising heartbeat, GPS sensors, and Android mobile phones.
Keywords: Data models; Ontologies; Security; Semantics; Sensor phenomena and characterization; Wireless sensor networks; BANs; OWL 2 DL; Pellet; Protege; WSNs; heterogeneity management; ontology; open data model; semantic; sensor (ID#: 15-4833)


Ismail, Ziad; Leneutre, Jean; Bateman, David; Chen, Lin; "A Game-Theoretical Model for Security Risk Management of Interdependent ICT and Electrical Infrastructures," High Assurance Systems Engineering (HASE), 2015 IEEE 16th International Symposium on, pp.101,109, 8-10 Jan. 2015. doi: 10.1109/HASE.2015.24 Abstract: The communication infrastructure is a key element for management and control of the power system in the smart grid. The communication infrastructure, which can include equipment using off-the-shelf vulnerable operating systems, has the potential to increase the attack surface of the power system. The interdependency between the communication and the power system renders the management of the overall security risk a challenging task. In this paper, we address this issue by presenting a mathematical model for identifying and hardening the most critical communication equipment used in the power system. Using non-cooperative game theory, we model interactions between an attacker and a defender. We derive the minimum defense resources required and the optimal strategy of the defender that minimizes the risk on the power system. Finally, we evaluate the correctness and the efficiency of our model via a case study.
Keywords: Communication equipment; Games; Nash equilibrium; Power grids; Security; Substations; Cyber-physical System; Non-cooperative Game Theory; SCADA Security (ID#: 15-4834)


Zhu, Y.; Yan, J.; Tang, Y.; Sun, Y.; He, H., "Joint Substation-Transmission Line Vulnerability Assessment Against the Smart Grid," Information Forensics and Security, IEEE Transactions on, vol. PP, no. 99, pp. 1, 1, 5 February 2015. doi: 10.1109/TIFS.2015.2394240 Abstract: Power grids are often run near the operational limits because of increasing electricity demand, where even small disturbances could possibly trigger major blackouts. The attacks are the potential threats to trigger large-scale cascading failures in the power grid. Specifically, the attacks mean to make substations/transmission lines lose functionality by either physical sabotages or cyber attacks. Previously, the attacks are investigated from node-only/link-only perspectives, assuming attacks can only occur on substations/transmission lines. In this paper, we introduce the joint-substation-transmission-line perspective, which assumes attacks can happen on substations, transmission lines, or both. The introduced perspective is a nature extension to substation-only and transmission-line-only perspectives. Such extension leads to discovering many joint-substation transmission line vulnerabilities. Furthermore, we investigate the joint-substation-transmission-line attack strategies. In particular, we design a new metric, the component interdependency graph (CIG), and propose the CIG-based attack strategy. In simulations, we adopt IEEE 30 bus system, IEEE 118 bus system and Bay Area power grid as test benchmarks, and use the extended degree-based and load attack strategies as comparison schemes. Simulation results show the CIG-based attack strategy has stronger attack performance.
Keywords: Load modeling; Measurement; Power system faults; Power system protection; Power transmission lines; Smart grids; Attack; Cascading Failures; Security; The Smart Grid; Vulnerability Analysis (ID#: 15-4835)


Urquidez, O.A.; Le Xie, "Smart Targeted Planning of VSC-Based Embedded HVDC via Line Shadow Price Weighting," Smart Grid, IEEE Transactions on, vol. 6, no. 1, pp. 431, 440, Jan. 2015. doi: 10.1109/TSG.2014.2354296 Abstract: In this paper, a novel approach to incorporate voltage source converter-based embedded HVDC for improving power system economic dispatch efficiency is proposed. An analytical formulation is presented to quantify the economic benefits of embedded HVDC by modeling its flow control as an injection-extraction pair in the economic dispatch of the transmission grid. A computationally efficient algorithm is proposed to rank the potential locations of such embedded HVDC. The algorithm is based on expected economic dispatch cost reduction weighted by the historical line shadow prices. The use of a distribution of historical data as a means of weighting also allows for incorporation of diurnal and seasonal influences on congestion patterns. Numerical case studies using the proposed method of locating the embedded HVDC suggest promising results in choosing the location of improved flow control devices.
Keywords: HVDC power convertors; cost reduction; load dispatching; load flow control; power transmission control; power transmission economics; power transmission planning; VSC-based embedded HVDC; economic benefits; economic dispatch; expected economic dispatch cost reduction; flow control devices; historical line shadow prices; injection-extraction pair; line shadow price weighting; power system economic dispatch efficiency; smart targeted planning; transmission grid; voltage source converter-based embedded HVDC; Economics; Generators; HVDC transmission; Planning; Power conversion; Vectors; Mixed ac/dc; security-constrained economic dispatch (SCED);transmission planning; voltage source converter (VSC) HVDC; wind curtailment (ID#: 15-4836)


Sun, Y.; Li, Z.; Shahidehpour, M.; Ai, B., "Battery-Based Energy Storage Transportation for Enhancing Power System Economics and Security," Smart Grid, IEEE Transactions on, vol.6, no.5, pp.2395-2402, Sept. 2015.  doi: 10.1109/TSG.2015.2390211 Abstract: This paper evaluates the effect of integrating battery-based energy storage transportation (BEST) by railway transportation network on power grid operation and control. A time-space network model is adopted to represent transportation constraints. The proposed model integrates the hoURLy security-constrained unit commitment with vehicle routing problem. The BEST solution provides the locational and hoURLy charging/discharging schedule of the battery storage system. The mobility of BEST will be of particular interest for enhancing the power system resilience in disaster areas where the transmission grid is congested or on outrage. Two cases are used to simulate the BEST including a six-bus power system linking with a three-station railway system, as well as the IEEE 118-bus systems linking with an eight-station railway system. The results show that under certain conditions, the mobility of battery storage system can economically relieve the transmission congestion and lower the operation costs.
Keywords: Batteries; Mathematical model; Power grids; Rail transportation; Renewable energy sources; Battery-based energy storage transportation (BEST); mixed-integer programming (MIP); security-constraint unit commitment (SCUC); time-space network (TSN) (ID#: 15-4837)


Yamaguchi, Y.; Ogawa, A.; Takeda, A.; Iwata, S., "Cyber Security Analysis of Power Networks by Hypergraph Cut Algorithms," Smart Grid, IEEE Transactions on, vol.6, no.5, pp.2189-2199, Sept. 2015. doi: 10.1109/TSG.2015.2394791 Abstract: This paper presents exact solution methods for analyzing vulnerability of electric power networks to a certain kind of undetectable attacks known as false data injection attacks. We show that the problems of finding the minimum number of measurement points to be attacked undetectably reduce to minimum cut problems on hypergraphs, which admit efficient combinatorial algorithms. Experimental results indicate that our exact solution methods run as fast as the previous methods, most of which provide only approximate solutions. We also present an algorithm for enumerating all small cuts in a hypergraph, which can be used for finding vulnerable sets of measurement points.
Keywords: False data injection; hypergraph; minimum cut; power network; security index; state estimation (ID#: 15-4838)


Lamadrid, A.J.; Shawhan, D.L.; Murillo-Sanchez, C.E.; Zimmerman, R.D.; Zhu, Y.; Tylavsky, D.J.; Kindle, A.G.; Dar, Z., "Stochastically Optimized, Carbon-Reducing Dispatch of Storage, Generation, and Loads," Power Systems, IEEE Transactions on, vol.30, no.2, pp.1064-1075, March 2015. doi: 10.1109/TPWRS.2014.2388214 Abstract: We present a new formulation of a hybrid stochastic-robust optimization and use it to calculate a look-ahead, security-constrained optimal power flow. It is designed to reduce carbon dioxide (CO2) emissions by efficiently accommodating renewable energy sources and by realistically evaluating system changes that could reduce emissions. It takes into account ramping costs, CO2 damages, demand functions, reserve needs, contingencies, and the temporally linked probability distributions of stochastic variables such as wind generation. The inter-temporal trade-offs and transversality of energy storage systems are a focus of our formulation. We use it as part of a new method to comprehensively estimate the operational net benefits of system changes. Aside from the optimization formulation, our method has four other innovations. First, it statistically estimates the cost and CO2 impacts of each generator's electricity output and ramping decisions. Second, it produces a comprehensive measure of net operating benefit, and disaggregates that into the effects on consumers, producers, system operators, government, and CO2 damage. Third and fourth, our method includes creating a novel, modified Ward reduction of the grid and a thorough generator dataset from publicly available information sources. We then apply this method to estimating the impacts of wind power, energy storage, and operational policies.
Keywords: Energy storage; Equations; Generators; Mathematical model; Optimization; Uncertainty; Vectors; Energy storage; environmental economics; optimization; power generation dispatch; power system economics; power system planning; power system simulation; renewable energy sources; smart grids; uncertainty; wind energy (ID#: 15-4839)


Li, Z.; Wang, J.; Sun, H.; Guo, Q., "Transmission Contingency Analysis Based on Integrated Transmission and Distribution Power Flow in Smart Grid," Power Systems, IEEE Transactions on, vol.30, no.6, pp.3356-3367, November 2015. doi: 10.1109/TPWRS.2014.2381879 Abstract: In future smart grids, with distribution networks having loops more frequently, current transmission contingency analysis (TCA) which usually neglects the distribution power flow variations after a contingency may leave out severe outages. With more distribution management systems deployed on the distribution side, a new transmission CA method based on global power flow (GPF) analysis which integrates both the transmission and distribution power flow is proposed in this paper (named as GTCA) to address the problem. The definition and new features of GTCA are first introduced. Then, the necessity of GTCA is physically illustrated. Difference in the results of GTCA and TCA is mathematically analyzed. A GPF-embedded algorithm of performing GTCA is then provided. The data exchange process and the performance with communication interruptions are discussed. As multiple contingencies are considered in GTCA, several approaches are proposed and discussed to reduce communication burdens and improve the computational efficiency. Plenty of numerical tests are performed in several systems to verify the theoretical analysis. With theoretical analysis and numerical verification, it is suggested that GTCA should be performed instead of TCA to avoid potential false alarms, especially in the condition that DNs are more frequently looped in the future smart grids.
Keywords: Equations; Generators; Power system reliability; Reliability; Security; Smart grids; Contingency analysis; GPF-based transmission CA; distribution; global power flow; master-slave-splitting; transmission (ID#: 15-4840)


Li, X.; Zhang, X.; Wu, L.; Lu, P.; Zhang, S., "Transmission Line Overload Risk Assessment for Power Systems With Wind and Load-Power Generation Correlation," Smart Grid, IEEE Transactions on, vol.6, no.3, pp.1233-1242, May 2015. doi: 10.1109/TSG.2014.2387281 Abstract: In the risk-based security assessment, probability and severity of events are the two main factors for measuring the security level of power systems. This paper presents a method for assessing line overload risk of wind-integrated power systems with the consideration of wind and load-power generation correlation. The established risk assessment model fully considers the probability and the consequence of wind uncertainties and line flow fluctuations. The point estimate method is employed to deal with the probability of line overload and the severity function is applied to quantify line flow fluctuations. Moreover, with the Cholesky decomposition, the correlation between loads and power generations are simulated by the spatial transformation of probability distributions of random variables. In addition, Nataf transformation is used to address wind resource correlation. Finally, the line overload risk index is obtained, which can be used as an indicator for quantifying power system security. Numerical results on the modified IEEE 30-bus system and the modified IEEE 118-bus system show that the types and the parameters of the wind speed distribution would affect the risk indices of line overload, and the risk indices obtained with the consideration of wind resource correlation and load correlation would reflect the system security more accurately.
Keywords: Correlation; Power generation; Power systems; Random variables; Risk management; Security; Wind speed; Load-power generation correlation; overload risk assessment; point estimate method (PEM);probabilistic load flow (PLF); severity function; wind resource correlation (ID#: 15-4841)


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