Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> We study the economic impact of a potential class of integrity cyber attacks, named false data injection attacks, on electric power market operations. In particular, we show that with the knowledge of the transmission system topology, attackers may circumvent the bad data detection algorithms equipped in today's state estimator. This, in turn, may be leveraged by attackers for consistent financial arbitrage such as virtual bidding at selected pairs of nodes. This paper is a first attempt to formalize the economic impact of malicious data attacks on real-time market operations. We show how an attack could systematically construct a profitable attacking strategy, in the meantime being undetected by the system operator. Such a result is also valuable for the system operators to examine the potential economic loss due to such cyber attack. The potential impact of the false data injection attacks is illustrated on real-time market operations of the IEEE 14-bus system. <s> BIB001 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> With the increase in use of information technology in advanced demand side management and given the growth in power consumption in the computation and communications sectors, a new class of cyberintrusion plans is emerging that aims to alter the load through the Internet and by means of automatic and distributed software intruding agents. These attacks work by compromising direct load control command signals, demand side management price signals, or cloud computation load distribution algorithms to affect the load at the most crucial locations in the grid in order to cause circuit overflow or other malfunctions and damage the power system equipment. To gain insights into these less-examined yet important intrusion strategies, in this paper, we identify a variety of practical loads that can be volnurable to Internet-based load altering attacks. In addition, we overview a collection of defense mechanisms that can help in blocking these attacks or minimizing the damage caused by them. Our simulation results based on the standard setting in the IEEE 24-bus Reliability Test System show that our proposed cost-efficent load protection strategy can significantly reduce the cost of load protection while it guarantees that no Internet-based load altering attack may overload the power distribution system. <s> BIB002 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> Covert data attacks on the network topology of a smart grid is considered. In a so-called man-in-the-middle attack, an adversary alters data from certain meters and network switches to mislead the control center with an incorrect network topology while avoiding detections by the control center. A necessary and sufficient condition for the existence of an undetectable attack is obtained for strong adversaries who can observe all meter and network data. For weak adversaries with only local information, a heuristic method of undetectable attack is proposed. Countermeasures to prevent undetectable attacks are also considered. It is shown that undetectable attacks do not exist if a set of meters satisfying a certain branch covering property are protected. The proposed attacks are tested with IEEE 14-bus and IEEE 118-bus system, and their effect on real-time locational marginal pricing is examined. <s> BIB003 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> This paper presents a new class of false data injection attacks on state estimation, which may lead to financial arbitrage in real-time power markets with an emerging look-ahead dispatch model. In comparison with prior work of cyber attack on static dispatch where no inter-temporal ramping constraint is considered, we propose a novel attack strategy with which the attacker can manipulate, in look-ahead dispatch, the limits of ramp constraints of generators. It is demonstrated that the proposed attack may lead to financial profits via malicious capacity withholding of selected generators, while being undetected by the existing bad data detection algorithm embedded in the state estimator. The feasibility of such cyber attacks and their economic impact on real-time electricity market operations are illustrated in the IEEE 14-bus system. <s> BIB004 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> The problem of characterizing impacts of data quality on real-time locational marginal price (LMP) is considered. Because the real-time LMP is computed from the estimated network topology and system state, bad data that cause errors in topology processing and state estimation affect real-time LMP. It is shown that the power system state space is partitioned into price regions of convex polytopes. Under different bad data models, the worst case impacts of bad data on real-time LMP are analyzed. Numerical simulations are used to illustrate worst case performance for IEEE-14 and IEEE-118 networks. <s> BIB005 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> This paper examines the impact of supervisory control and data acquisition (SCADA) data corruption on real-time locational marginal price (LMP) in electricity markets. We present an analytical framework to quantify LMP sensitivity with respect to changes in sensor data. This framework consists of a unified LMP sensitivity matrix subject to sensor data corruption. This sensitivity matrix reflects a coupling among the sensor data, an estimation of the power system states, and the real-time LMP. The proposed framework offers system operators an online tool to: 1) quantify the impact of corrupted data at any sensor on LMP variations at any bus; 2) identify buses with LMPs highly sensitive to data corruption; and 3) find sensors that impact LMP changes significantly and influentially. It also allows system operators to evaluate the impact of SCADA data accuracy on real-time LMP. The results of the proposed sensitivity based analysis are illustrated and verified with IEEE 14-bus and 118-bus systems with both Ex-ante and Ex-post real-time pricing models. <s> BIB006 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> Cyber-attacks on electric energy markets could have tremendous financial impacts in a deregulated power system. Existing indices fail to quantify the financial impacts effectively under intelligently conceived attacks. This paper identifies the conditions under which existing metrics would fail and proposes an improved impact index to better quantify the financial impacts of such attacks. Actual attack simulations on an approximate equivalent of the power system in Arizona are used to verify the effectiveness of the proposed metric. <s> BIB007 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> A variety of distributed energy management algorithms are being developed for DC optimal power flow (DCOPF) application owing to their flexibility and scalability in the presence of high distributed Energy Resources (DERs) penetration. However, these algorithms are vulnerable to malicious cyber attacks due to the absence of control centers. In this paper, we study and analyze the economic impact of the data integrity attack to distributed DC-OPF algorithms. In particular, we demonstrate how a malicious generator could gain more economic profit by compromising the distributed controller of its bus, modifying the information sent to neighboring buses and manipulating the power dispatch commands. To our best knowledge, this is the first paper to show the economic impact of malicious attacks in distributed DC-OPF. By revealing such potential financial risks, this paper conveys the message that besides the efforts of designing novel distributed energy management algorithms to address the DERs integration challenges, it is equally important to protect the distributed energy management algorithms from possible malicious attacks to avoid potential economic loss. The economic impact of the data integrity attack is illustrated in the Future Renewable Electric Energy Delivery and Management (FREEDM) system. <s> BIB008 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> Modern information and communication technologies used by electric power grids are subject to cyber-security threats. This article studies the impact of integrity attacks on real-time pricing (RTP), an emerging feature of advanced power grids that can improve system efficiency. Recent studies have shown that RTP creates a closed loop formed by the mutually dependent real-time price signals and price-taking demand. Such a closed loop can be exploited by an adversary whose objective is to destabilize the pricing system. Specifically, small malicious modifications to the price signals can be iteratively amplified by the closed loop, causing highly volatile prices, fluctuating power demand, and increased system operating cost. This article adopts a control-theoretic approach to deriving the fundamental conditions of RTP stability under basic demand, supply, and RTP models that characterize the essential behaviors of consumers, suppliers, and system operators, as well as two broad classes of integrity attacks, namely, the scaling and delay attacks. We show that, under an approximated linear time-invariant formulation, the RTP system is at risk of being destabilized only if the adversary can compromise the price signals advertised to consumers, by either reducing their values in the scaling attack or providing old prices to over half of all consumers in the delay attack. The results provide useful guidelines for system operators to analyze the impact of various attack parameters on system stability so that they may take adequate measures to secure RTP systems. <s> BIB009 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> The potential economic impact of transmission line rating (TLR) attacks in two-settlement electricity markets is studied in this paper. We show that nodal prices in real-time markets can be manipulated via a TLR attack, which can be modeled as a bi-level optimization problem. Several acceleration techniques are developed to reduce the computational burden of solving the bi-level problem. A heuristic strategy is proposed to deal with the issue of multiplicity in pricing. The uncertainties in load are also considered in the proposed TLR model. Numerical simulations demonstrate that well-designed TLR attacks can manipulate the profits of market participants in the two-settlement markets. Benchmark testing shows that the proposed acceleration techniques can reduce computation time tremendously, and the proposed heuristic strategy can mitigate the issue of multiplicity in pricing. <s> BIB010 </s> Cyber-physical attacks and defences in the smart grid: a survey <s> Electricity market attacks <s> Recent work has studied the impact caused by attackers that compromise pricing signals used in the emerging retail electricity market and send false prices to a subset of consumers. In this paper, we extend previous work by considering a more realistic adversary model that is not arbitrarily tied to scaling and delay attacks, but that can generate any arbitrary pricing signal and show how to keep the problem tractable with a new analysis based on sensitivity functions. In addition, we extend previous work by proposing countermeasures to mitigate the negative impact of these attacks. Countermeasures include selecting parameters of the controller, designing robust control algorithms, and by detecting anomalies in the behavior of the system. <s> BIB011
In the smart grid, the price of electricity is determined by the locational marginal prices (LMPs) from the day-ahead and RT markets, which are both obtained by solving respective OPF problems. Recall that in Fig. 6 , the solution of OPF is dependent on the network topology and estimated system states; as a result, the LMP is also vulnerable to SE attacks BIB005 . CP attack schemes exploit the RT LMP vulnerability in the transmission congestion management. A transmission congestion occurs when the power flow on transmission lines reach the line capacity (i.e. the thermal rating limit). To meet the electricity request under congested conditions, generators in the vicinity will be temporarily dispatched, which are often considerably more costly. As a result, the price of electricity is affected dramatically on an imminent congestion. An attacker can leverage this mechanism to gain illegal profit from the price margin before and after the attack or induce frequent transmission congestion to impose expensive operations to the system. Investigations have identified several feasible schemes targeting the RT markets. Attacks schemes have been developed based on vulnerabilities in virtual bidding mechanism BIB001 , system topology information BIB003 , generation ramping limits BIB004 , and distributed energy management BIB008 . The sensitivity of LMP to the corrupted sensor data has been investigated in BIB006 , and an index to quantify the impacts of electricity market attacks has been proposed BIB007 . Instead of manipulating the line flow in the measurements, the line ratings can also be attacked to induce transmission congestion BIB010 . The RT pricing system is also vulnerable under data integrity attacks, e.g. scaling and delay attacks, which will cause demand/price fluctuations as well as increase system operating costs BIB009 . A stealth scheme to generate arbitrary pricing signals has been further proposed in BIB011 . In addition to the impacts on the control and management side, the hijacked pricing information can alter the load demand of customers, which will retroactively create overloading and instabilities in the system BIB002 .