Bilevel Model for Analyzing Coordinated Cyber-Physical Attacks on Power Systems

Abstract

This paper analyzes a coordinated cyber-physical attack on power systems, which could lead to undetectable line outages. Coordinated with physical attacks that cause line outages, the two-step cyberattacks comprising topology preserving and load redistribution attacks could mask and potentially exasperate outages to trigger cascading failures. These coordinated cyber-physical attacks are analyzed in a proposed bilevel model, which aims at identifying the most damaging and undetectable physical attacks constrained by attackers' total budget. After being transformed into a mixed-integer linear programming problem, the proposed bilevel model is solved by a rigorous two-stage solution approach. This paper also discusses the relevant countermeasure strategies. The proposed model, the solution algorithm, and the effectiveness of countermeasures are examined by case studies based on the IEEE 14-and 118-bus test systems.Index Terms-Bilevel model, countermeasure strategies, cyber-physical systems, mixed-integer linear programming, topology preserving and load redistribution attacks.

Moving-Target Defense for Detecting Coordinated Cyber-Physical Attacks in Power Grids

“…In particular, FDI attacks against power grid state estimation have been extensively studied [10], [11], [12]. While FDI attacks affect only the sensor measurements that are conveyed to the control center (and hence consist only of a cyber attack), recent research [3], [4], [5], [6] has studied CCPAs attacks, which as noted above consist of both cyber and physical components. CCPAs were first proposed in [3] based on disconnecting a set of transmission lines and blocking sensor measurements from the attacked area.…”

“…Moreover, under some conditions, it was shown that the operator can recover the phase angles and detect the physical attack using information from outside the attacked zone [3]. On the other hand, [4], [5] and [6] proposed the design of cyber attacks that can completely mask the effects of the physical attack under different assumptions about the attacker's knowledge. Further, [4], [5] and [6] have also investigated defense against CCPAs relying on a subset of protected measurements, which however is vulnerable (see Section I).…”

“…communication vulnerabilities [2]. CCPAs can have severe effects on the grid, since undetected line/generator outages may trigger cascading failures, and have received significant recent attention [3], [4], [5], [6].…”

“…As in prior works [3], [4], [5], [6], we only consider physical attacks that disconnect the transmission lines. We note that to craft an undetectable CCPA, the attacker must obtain an accurate knowledge of certain line reactances [4], [6]. The main idea of the proposed MTD defense in this context is to invalidate the attacker's prior acquired knowledge by actively perturbing of the grid's line reactance settings.…”

“…Set A am,dn = A a 0 ,d 0 . Solve (3) to obtain COPF(a0, dn) 4. if attack is successful thenRecompute power flows after removing the branches in La m .…”