Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> Effective simulation of large-scale power system disturbances especially those stemming from intentional attack represents an open engineering and research problem. Challenges stem from the need to develop intelligent models of cyber-physical attacks that produce salient disruptions, to appropriately portray meaningful cyber-physical interdependencies, and balance precision, scale and complexity. In this paper, we present a foundation for the development of a class of intelligent cyber-physical attacks that we term coordinated switching attacks. Our approach, based on variable structure systems theory, is amenable to implementation in well known power system simulators. We provide a method to construct such attack models and demonstrate their utility in the simulation of extensive system disturbances. Our results demonstrate the potential for coordinated switch attacks to enable large-scale power system disturbances. <s> BIB001 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> In this paper, we present the development of a new class of intelligent cyber-physical attacks termed coordinated switching attacks whereby opponents aim to destabilize the power grid through controlled switching. Such switching is facilitated by cyber attack and corruption of communication channels and control signals of the associated switch(es). The attack employs a variable structure systems theory model of a smart grid. The sliding mode theory is employed to leverage emergent system properties to identify state-dependent switching sequences to disrupt power flow. Our results demonstrate the potential for coordinated switch attacks to enable large-scale power system disturbances. <s> BIB002 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> In this paper we have proposed an approach for vulnerability analysis of a class of cyber-physical reconfiguration attacks called coordinated variable structure switching. In such an attack, an opponent who gains control over a target circuit breaker, relay or switch can apply a given switching sequence to destabilize the system even if the system is stable in static switch positions. Our analysis approach is illustrated through a case study of the Western Electricity Coordinating Council 3-machine, 9-bus system. MATLAB and PSCAD® simulations are employed to validate the approach. Moreover the insights gained from the vulnerability analysis of the WECC system are consistent with intuition. <s> BIB003 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> Coordinated variable structure switching attacks have been recently proposed as a class of cyber-physical attacks on future smart grid systems. In the traditional formulation of this assault, the opponent is assumed to have a local model of the power system and knowledge of the state (rotor angle and frequency) of a target generator under attack. In this paper, we study the performance of this attack when the opponent has imperfect knowledge of the local system dynamics and partial knowledge of the generator state. In such a situation, we demonstrate how the attacker can make use of Luenberger-based state estimation techniques that are robust to model error to still achieve power system disruption via rotor angle instability. <s> BIB004 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> Security issues in cyber-physical systems are of paramount importance due to the often safety-critical nature of its associated applications. A first step in understanding how to protect such systems requires an understanding of emergent weaknesses, in part, due to the cyber-physical coupling. In this paper, we present a framework that models a class of cyber-physical switching vulnerabilities in smart grid systems. Variable structure system theory is employed to effectively characterize the cyber-physical interaction of the smart grid and demonstrate how existence of the switching vulnerability is dependent on the local structure of the power grid. We identify and demonstrate how through successful cyber intrusion and local knowledge of the grid an opponent can compute and apply a coordinated switching sequence to a circuit breaker to disrupt operation within a short interval of time. We illustrate the utility of the attack approach empirically on the Western Electricity Coordinating Council three-machine, nine-bus system under both model error and partial state information. <s> BIB005 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> Security issues related to power grid networks have attracted the attention of researchers in many fields. Recently, a new network model that combines complex network theories with power flow models was proposed. This model, referred to as the extended model, is suitable for investigating vulnerabilities in power grid networks. In this paper, we study cascading failures of power grids under the extended model. Particularly, we discover that attack strategies that select target nodes (TNs) based on load and degree do not yield the strongest attacks. Instead, we propose a novel metric, called the risk graph, and develop novel attack strategies that are much stronger than the load-based and degree-based attack strategies. The proposed approaches and the comparison approaches are tested on IEEE 57 and 118 bus systems and Polish transmission system. The results demonstrate that the proposed approaches can reveal the power grid vulnerability in terms of causing cascading failures more effectively than the comparison approaches. <s> BIB006 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> This paper explores distributed smart grid attack strategies to destabilize power system components using variable structure system theory. Here, an opponent is able to remotely control multiple circuit breakers within a power system, say through data corruption or communication network attack, to destabilize target synchronous generators through application of state-dependent breaker switching. In contrast to attack via a single breaker, the multi-switch case provides additional degrees of freedom that can lead to stealthier and wide-scale cascading failures. We provide a dynamical systems context for formulating distributed multi-switch strategies and execute such attacks on the New England 10-generator 39-bus test system. <s> BIB007 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> Switching attacks in smart grid systems have gained some recent attention by the research community. Based on understanding the structure of the physical system and accessing the system variables, effective sliding-mode switching attacks can be used to disrupt the normal operation of the power grid. This article investigates the practical limitations of such attacks. Sliding-mode switching attacks on a single-machine infinite-bus system are considered in this work, and the impact of some practical limitations is investigated. These limitations include sampling period, quantization level, signal-to-noise ratio, hysteresis margin and minimum time to switch of a circuit breaker, and communication latency. Results of this work detail the effectiveness of the sliding-mode switching attacks under different practical limitations. <s> BIB008 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> CP switching attacks: <s> A new class of switching attacks in smart grid systems is investigated in this work. The proposed attack relies on calculated switchings of a fast-acting energy storage system (ESS) in order to drive the system state variable of the target generator beyond the stability boundary. Based on understanding the structure of the power system, an adversary uses the swing equation to find the stability boundary of the target generator. In order to conduct a successful switching attack, the adversary intercepts the power system's measurements and switches the circuit breaker of the ESS back-and-forth depending on the value of system state variable. Numerical results show the effectiveness of the proposed switching attack when applied to the New England power system. <s> BIB009
The switching attack is another family of CP attacks developed against the power transmission systems BIB001 BIB002 BIB003 BIB004 . Circuit breakers can switch the transmission A risk graph is constructed to conduct sequential substation attacks BIB006 systems between complex discontinuous dynamics. Given the system state x, the switching signal s(x, t), and two distinctive system dynamics f 1 and f 2 , the non-linear power system can be presented by the following variable structure system BIB005 BIB007  An informed attacker can issue malicious switching signals to re-configure the power transmissions based on local structure information, and the switched system is subsequently steered to a degraded or unstable operation states. With consideration of model errors and incomplete information, the investigation has shown that single switching attack will cause frequency and voltage instabilities in the system BIB005 . In addition, multi-switching attacks on distributed circuit breakers are able to initiate a series of cascading failures BIB007 . Recently, it has been shown that the switching attacks can also exploit the energy storage systems to destabilise the transmission systems BIB009 . Some discussion regarding the practical limitations of the switching attack have been provided in terms of sampling, quantification, and signal-to-noise ratio BIB008 .