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The intermittent nature of wind generation makes essential the development of new tools to support the security assessment of electrical power systems (EPS) with this type of alternative energy source. In this context, the static security region (SSR) is a powerful tool that allows the steady-state security assessment of a EPS through visual inspections. The nomograms enable to carry out a fast analysis of the possible generation scenarios that a system can assume without violating its security limits. Therefore, the mains objective of this paper is to include a new security limit in the SSR, to complement the security assessment. This new limit is associated with intermittent generation sources, such as wind farms. For that purpose, an algorithm for the automatic construction of SSR is presented, where this new security limit was incorporated. The proposed methodology is applied to the well-known New England test system. The results presented validate and indicate the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

Abstract Satisfying the growing energy demand, power systems are required to increase their capacity and be able to distribute energy over wider geographical area. To maintain the reliability of such power systems, more dependence is placed on automating the process controlling the physical system. Such power systems are known as smart grids, where data is transmitted in real-time across the power grid facilitating automated actions. These smart systems have intrinsic vulnerabilities. A smarter power grid is more reliant on an ICT backbone. Such reliance renders the physical power system subjected to an ICT realm whose security depends on a set of metrics, and standards alien to those of classical power systems. The sustainability of a power system will depend on the secure and reliable operation of the new smart system. This paper proposes a comprehensive approach to solve the challenges enumerated above. The proposed approach sets the ground for new metrics of overall system sustainability, by dissecting the overall smart grid into three layers: the physical system, the SCADA system, and the ICT infrastructure. The proposed methodology is tested on the case of electric vehicles, where cyber intrusion scenarios are studied in light of their effect on the physical layer. [ABSTRACT FROM AUTHOR]

Contingency ranking is one of the most important stages in the analysis of power system security. In this paper, an integrated algorithm has been proposed to address this issue. This algorithm employs neural networks method to quickly estimate the power system parameters and Stochastic Frontier Analysis (SFA) in order to calculate the efficiency of each contingency. Network security indices (voltage violation and line flow violation) and economic indices (locational marginal price and congestion cost) have been simultaneously considered to rank the contingencies. The efficiency of each contingency shows its severity, and indicates that it affects network security and economic indices concurrently. The proposed algorithm has been tested on IEEE 14-bus and 30-bus test power systems. Simulation results show the high efficiency of the algorithm. Test results indicate that predicted quantities are estimated accurately and quickly. The proposed method is capable of producing fast and accurate network security and economic indices, so that it can be used for online ranking. [ABSTRACT FROM AUTHOR]

Power system security analysis plays key role in enhancing the system security and to avoid the system collapse condition. In this paper, a novel severity function is formulated using transmission line loadings and bus voltage magnitude deviations. The proposed severity function and generation fuel cost objectives are analyzed under transmission line(s) and/or generator(s) contingency conditions. The system security under contingency conditions is analyzed using optimal power flow problem. An improved teaching learning based optimization (ITLBO) algorithm has been presented. To enhance the system security under contingency conditions in the presence of unified power flow controller (UPFC), it is necessary to identify an optimal location to install this device. Voltage source based power injection model of UPFC, incorporation procedure and optimal location identification strategy based on line overload sensitivity indexes are proposed. The entire proposed methodology is tested on standard IEEE-30 bus test system with supporting numerical and graphical results. [ABSTRACT FROM AUTHOR]

The paper presents an assessment of the functional mechanisms that are part of the security system for the power grid control. The security system, its components, and the real time processes for the control of electricity supply were defined. In particular, SCADA protocols used in the control system and mechanisms for transferring them between the control center and actuators were identified. The paper also includes presentation of a test environment that is used for developed security mechanisms evaluation. In the last fragment of the paper, the test scenarios were formulated and the results obtained in the cyber security system were shown, which cover security probes reaction delay, forged malicious IEC 60870-5-104 traffic detection, DarkNet and HoneyPot interception of adversary actions, and dynamic firewall rules creation. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents and evaluates a new cryptographic key management scheme which increases the efficiency and security of the Supervisory Control And Data Acquisition (SCADA) communication. In the proposed key management scheme, two key update phases are used: session key update and master key update. In the session key update phase, session keys are generated in the master station. In the master key update phase, the Elliptic Curve Diffie–Hellman (ECDH) protocol is used. The Poisson process is also used to model the Security Index (SI) and Quality of Service (QoS). Our analysis shows that the proposed key management not only supports the required speed in the MODBUS implementation but also has several advantages compared to other key management schemes for secure communication in SCADA networks. [Copyright &y& Elsevier]

Recently, as a demand for connecting Supervisory Control and Data Acquisition (SCADA) systems to open networks increases, the study of SCADA system security becomes an issue. Many researchers have proposed key management schemes for SCADA systems. However, previous studies lack the proper considerations for availability. In this paper, we build up cryptographic security requirements for robust SCADA systems. In addition, we propose a hybrid key management architecture for robust SCADA systems which supports replace protocol for availability and reduces the number of keys to be stored in a master terminal unit. [ABSTRACT FROM AUTHOR]

Potential catastrophic events have been historically assessed through the techniques of power system security analysis. A correct assessment must consider not only events associated with "credible outages" but also the possibility of attacks and/or "rare" events. This paper combines concepts of reliability engineering and operations research to develop a new importance measure, D(α), that identifies the most vulnerable group of α links in a network. Since the computation of the new importance measure, D(α), becomes computationally prohibitive for large systems, an approximation technique is provided based on the optimization of a multi-objective deterministic network interdiction problem. The efficiency of the algorithm is then illustrated by analyzing the Italian high-voltage electrical transmission network. In summary, D(α) can be useful for an initial screening of the critical elements of the network. [ABSTRACT FROM AUTHOR]

Abstract: Power transmission grids play a crucial role as a critical infrastructure by assuring the proper functioning of power systems. In particular, they secure the loads supplied by power generation plants and help avoid blackouts that can have a disastrous impact on society. The power grid structure (number of nodes and lines, their connections, and their physical properties and operational constraints) is one of the key issues (along with generation availability) to assure power system security; consequently, it deserves special attention. A promising approach for the structural analysis of transmission grids with respect to their vulnerabilities is to use metrics and approaches derived from complex network (CN) theory that are shared with other infrastructures such as the World-Wide Web, telecommunication networks, and oil and gas pipelines. These approaches, based on metrics such as global efficiency, degree and betweenness, are purely topological because they study structural vulnerabilities based on the graphical representation of a network as a set of vertices connected by a set of edges. Unfortunately, these approaches fail to capture the physical properties and operational constraints of power systems and, therefore, cannot provide meaningful analyses. This paper proposes an extended topological approach that includes the definitions of traditional topological metrics (e.g., degrees of nodes and global efficiency) as well as the physical/operational behavior of power grids in terms of real power-flow allocation over lines and line flow limits. This approach provides two new metrics, entropic degree and net-ability, that can be used to assess structural vulnerabilities in power systems. The new metrics are applied to test systems as well as real power grids to demonstrate their performance and to contrast them with traditional, purely topological metrics. [Copyright &y& Elsevier]