The significance of modern power grids is acknowledged every time there is a major threat. This paper proposes the novel approaches to aid power system planner to improve power grid resilience by making appropriate hardening strategies against man-made attack or natural hazards. The vulnerability indices are introduced, which return the most vulnerable component in the system based on a tri-level defender-attacker-operator (DAO) interdiction problem which solves iteratively. The output of DAO is the set of hardening strategies that optimally allocated along the network to mitigate the impact of the worst-case damages. By repeating DAO problem based on the proposed algorithm, the various crafted attack is imposed on the system, and the defender's behavior demonstrates how an element is vulnerable to threats. The WSCC 9-bus, IEEE 24-bus, and IEEE 118-bus systems are employed to evaluate the model performance. The counter-intuitive results are proven by the proposed robust hardening strategy, which shows how the hardening strategy should be allocated to improve power network resilience against threats.

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Intentional controlled islanding (ICI) is a final resort for preventing a cascading failure and catastrophic power system blackouts. This paper proposes a controlled islanding algorithm that uses spectral clustering over multilayer graphs to find a suitable islanding solution. The multicriteria objective function used in this controlled islanding algorithm involves the correlation coefficients between bus frequency components and minimal active and reactive power flow disruption. Similar to the previous studies, the algorithm is applied in two stages. In the first stage, groups of coherent buses are identified with the help of modularity clustering using correlation coefficients between bus frequency components. In the second stage, the ICI solution with minimum active and reactive power flow disruption and satisfying bus coherency is determined by grouping all nodes using spectral clustering on the multi-layer graph. Simulation studies on the IEEE 39-bus test system demonstrate the effectiveness of the method in determining an islanding solution in real time while addressing the generator coherency problem.

We propose a new methodology based on modularity clustering of synchronization coefficient, to identify coherent groups of generators in the power grid in real-time. The method uses real-time integrity indices, i.e., the Generators Connectivity Index (GCI) that represents how generators are coherently strong within the groups, the Generator Splitting Index (GSI) that reveals to what extent the generators in different groups tend to swing against the other groups, and the System Separation Index (SI) which discloses the overall system separation status. We demonstrate how these integrity indices can be used to study the dynamic behavior of the power system. Furthermore, a comparison analysis is conducted between the synchronization coefficient (KS) and the generator rotor angle correlation coefficient (CC). The proposed indices demonstrate the dynamic behavior of power system following occurrence the faults and thus represent a promising approach in power system islanding studies. Our methodology is simple, fast, and computationally attractive. Simulation case performed on IEEE 118-bus systems demonstrates the efficacy of our approach.

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Oil-and-gas networks are systems of pumps and pipelines that are exposed to heterogeneous threats. Accordingly, hardening strategies against malicious attacks are needed in today’s geopolitical climate. In this paper, a tri-level leader–follower–operator game is established for determining the optimal fortification tactics to protect the critical assets considering the petroleum firm limited resources. We additionally consider defender options beyond outright fortification including tactics often adapted in the fog of war, such as deception. These are mathematically modeled under shared cognition concepts. The proposed model assumes a trial-and-error learning process to gradually discover effective defense strategies. These strategies may include a network defender projecting false information in the media or on the front lines to deceive the aggressor. The resulting mixed-integer nonlinear programming problem is decomposed into a master problem associated with deception and sub-problem as response strategies. A column-and-constraint generation solution duly takes into account the defender–operator and attacker–operator interactions. Further, linearization techniques are applied to reformulate the problem into a mixed-integer linear problem. Our studies performed on the part of the Iraq oil-and-gas network and computational results verified that the deception concept is much more effective than fortification, where the cost of attackers damages diminished significantly without substantial resources commitment on the part of the defender.

The reported work points at developing a practical approach for power transmission planners to secure power networks from potential deliberate attacks. We study the interaction between a system planner (defender) and a rational attacker who threatens the operation of power grid. In addition to the commonly used hardening strategy for protecting the network, a new sort of resources is introduced under the deception concept. Feint and deception are acknowledged as effective tools for misleading the attacker in strategic planning. To this end, the defender deception is mathematically formulated by releasing misinformation about his plan in the shared cognition-based model. To reduce the risk of damage in case of deception failure, preemptive-goal programming is utilized to prioritize the hardening strategy for the vital components. Furthermore, the "value of posturing" is introduced which is the benefits that the deception brings to the system. The problems are formulated as tri-level mixedinteger linear programming and solved by constraint-and-column generation method. Comprehensive simulation studies performed on WSCC 9-bus and IEEE 118-bus systems indicate how the defender will save significant cost from protecting his network with posturing rather than hardening and the proposed approach is a promising development to ensure the secure operation of power networks.

After a sudden disturbance, the energy balance of generators is disturbed, and the power outputs of synchronous generators vary as their rotor angles shift from their equilibrium points. This trend essentially presents the versatile response of each machine to the disturbance. Because of this change, the phase angle of the bus also differs. Hence, the versatile response of each machine can be assessed by the phase angles change at the buses close to the synchronous generator. This paper introduces a new methodology for discovering the degree of coherency among buses using the correlation index of the voltage angle between each pair of buses and use the Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) to partition the network into islands. The proposed approach also provides the network integrity indices (connectivity, splitting, and separation) for studying the dynamic nature of the power network system. The approach is assessed on an IEEE-39 test system with a fully dynamic model. The simulation results presented in this paper demonstrate the efficiency of the proposed approach.