Set-Theoretic Detection of Bias Injection Cyber-Attacks on Networked Power Systems

Tzes

J. Mod. Power Syst. Clean Energy

2018

Self Cite

This paper addresses a set-theoretic method for the detection of data corruption cyber-attacks on the load frequency control loop of a networked power system. The system consists of several interconnected control areas forming a power grid. Based on the overall discrete-time network dynamics, a convex and compact polyhedral robust invariant set is extracted and is used as a set-induced anomaly detector. If the state vector exits the invariant set, then an alarm will be activated, and the potential threat is considered disclosed. The attack scenario used to assess the efficiency of the proposed anomaly detector concerns corrupted frequency sensor measurements transmitted to the automatic generation control unit of a compromised control area. Simulation studies highlight the ability of a set-theoretic approach to disclose persistent and intermittent attack patterns even when they occur at the same time with changes in the power load demand.

Section: Introductionmentioning

confidence: 80%

Set-theoretic detection of data corruption attacks on cyber physical power systems

Tzes

J. Mod. Power Syst. Clean Energy

2018

Self Cite

“…The algorithms used for the calculation of the robust invariant sets, and thus for the design of the set-theoretic detectors, involve discrete-time systems [26,27]. In this work, we aim to develop an estimation-based detector and then combine it with a set-theoretic one.…”

Section: System Descriptionmentioning

confidence: 99%

“…It is shown that the only way to quantify the discrepancies of the estimation residue is to exploit the safety constraints of the state variables and resort to set-theoretic methods. In addition, we prove that we are mathematically inclined to determine the robust invariant set based not on the dynamics of the estimator but based on the dynamics of the system itself, inevitably resorting to the detectors developed in [26,27].…”

Section: Introductionmentioning

confidence: 98%

“…These fluctuations are dangerous since they stress the tie line to its thermal limit and can cause the coupled generators to desynchronize. The primary objective is to establish a mathematical link between the classical estimation-based attack detectors [25] and their recently introduced set-theoretic counterparts, proposed in [26,27]. The idea is to combine the best traits of the two methods and develop a hybrid detector, which performs better than each detector alone in the case of intermittent attacks.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, a set-theoretic attack detector relies on the extraction of suitable robust invariant sets, which stem from safety considerations and are used as sets of alarm constraints [26,27]. A set is said to be robust invariant with respect to the dynamics of a system, when the state trajectories emanating from every initial condition that belongs to this set remain within the same set for every future time instant and for every admissible disturbance sequence [28].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Hybrid Detection of Intermittent Cyber-Attacks in Networked Power Systems

Tzes²,

2019

Energies

Self Cite

This article addresses the concept of a compound attack detection mechanism, that links estimation-based and set-theoretic methods, and is mainly focused on the disclosure of intermittent data corruption cyber-attacks. The detection mechanism is developed as a security enhancing tool for the load-frequency control loop of a networked power system that consists of several interconnected control areas. The dynamics of the power network are derived in observable form in the discrete-time domain, considering that an adversary corrupts the frequency measurements of certain control areas by means of a bias injection cyber-attack. Simulations indicate that an estimation-based detector is unable to discern an intermittent attack, especially when the latter one occurs at the same time as changes in the power load. The detector can be improved by exploiting the safe operation constraints imposed on the state variables of the system. It is shown that the disclosure of intermittent data corruption cyber-attacks in the presence of unknown power load changes is guaranteed only when the estimation-based detector is combined with its set-theoretic counterpart. To this end, a robust invariant set for the networked power system is computed and an alarm is triggered whenever the state vector exits this set. Simulations indicate that the above detectors can operate jointly in terms of a hybrid scheme, which enhances their detection capabilities.

Modelling issues and aggressive robust load frequency control of interconnected electric power systems

International Journal of Control

Vlahakis

et al. 2020

This article is concerned with modelling, controllability analysis and the design of aggressive robust controllers for interconnected electric power systems. The load/frequency controller relies on a pole clustering scheme and provides the fastest transient response despite any disturbance load application. The inherent saturation constraints are handled by the combination of a controller gain minimization scheme and an anti-windup enhanced controller design which provides stability guarantees, while avoiding frequency and tie-line power oscillations. For this scheme, particular attention should be paid on the modeling aspects of the power system. It is shown that due to the positive semidefinite graph-connection Laplacian of the system, a reduction of the state vector is necessary. Simulation studies are offered to illustrate the effectiveness of the suggested scheme.