energies Review Enhancing Cybersecurity in Smart Grids: False Data Injection and Its Mitigation Derya Betul Unsal 1,* , Taha Selim Ustun 2 , S. M. Suhail Hussain 2 and Ahmet Onen 3 1 Department of Energy Science and Technology, Renewable Energy Research Center, Cumhuriyet University, Sivas 58140, Turkey 2 Fukushima Renewable Energy Institute, AIST (FREA), Koriyama 963-0298, Japan; [email protected] (T.S.U.); [email protected] (S.M.S.H.) 3 Department of Electrical and Electronics Engineering, Abdullah Gul University, Kayseri 38170, Turkey; [email protected] * Correspondence: [email protected]; Tel.: +90-(346)-219-1153 Abstract: Integration of information technologies with power systems has unlocked unprecedented opportunities in optimization and control fields. Increased data collection and monitoring enable control systems to have a better understanding of the pseudo-real-time condition of power systems. In this fashion, more accurate and effective decisions can be made. This is the key towards mitigating negative impacts of novel technologies such as renewables and electric vehicles and increasing their share in the overall generation portfolio. However, such extensive information exchange has created cybersecurity vulnerabilities in power systems that were not encountered before. It is imperative that these vulnerabilities are understood well, and proper mitigation techniques are implemented. This paper presents an extensive study of cybersecurity concerns in Smart grids in line with latest developments. Relevant standardization and mitigation efforts are discussed in detail and then the classification of different cyber-attacks in smart grid domain with special focus on false data injection (FDI) attack, due to its high impact on different operations. Different uses of this attack as well as Citation: Unsal, D.B.; Ustun, T.S.; developed detection models and methods are analysed. Finally, impacts on smart grid operation and Hussain, S.M.S.; Onen, A. Enhancing Cybersecurity in Smart Grids: False current challenges are presented for future research directions. Data Injection and Its Mitigation. Energies 2021, 14, 2657. https:// Keywords: smart grid cybersecurity; false data injection; power system operation; power system doi.org/10.3390/en14092657 protection; cybersecurity attacks; intruder detection; cybersecurity for scada systems Academic Editor: Seon-Ju Ahn Received: 12 April 2021 1. Introduction Accepted: 28 April 2021 The traditional electricity grid system of the 20th century is insufficient to meet today’s Published: 6 May 2021 needs. Novel technologies such as Electric Vehicles (EVs), smart inverters and renewable energy-based generators are continually being deployed [1]. They change power system Publisher’s Note: MDPI stays neutral operation paradigms, introduce bi-lateral power flow and create a dynamic operation with regard to jurisdictional claims in structure which was not originally envisioned [2]. To tackle these issues, power systems are published maps and institutional affil- equipped with more measurement, communication, and control capabilities. More accurate iations. information about the grid’s current state can be obtained in this fashion, and a decision can be made in pseudo-real time [3]. This modern power system structure is collectively called the Smart Grid (SG). There are many definitions of SG concept, such as “A network where all consumers can reach efficient, cheap, accessible, and reliable energy by using control and Copyright: © 2021 by the authors. communication technologies” [4]. Alternatively, SG is a system that is adaptive, reliable, Licensee MDPI, Basel, Switzerland. interactive and allows for renewable energy sources integration and optimization [5,6]. This article is an open access article In addition to these definitions, the National Institute of Standards and Technology (NIST) distributed under the terms and gives a high-level perspective and classifies SGs. Moreover, application characteristics and conditions of the Creative Commons requirements of SG infrastructure are divided into different layers [7]: Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ • Application; 4.0/). • Security; Energies 2021, 14, 2657. https://doi.org/10.3390/en14092657 https://www.mdpi.com/journal/energies Energies 2021, 14, x FOR PEER REVIEW 2 of 38 Energies 2021, 14, 2657 2 of 36 • Application; • Security; •• Communication;Communication; •• ControlControl of of Power; Power; •• PowerPower system.system. AsAs shownshown inin FigureFigure1 ,1, SGs SGs are are divided divided into into generation, generation, transmission, transmission, distribution, distribution, serviceservice providers,providers, and and consumers. consumers. 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When research recent is examined, research itis canexamined, be understood it can be that understood traditional that cybersecurity traditional cybersecu- methods andrity algorithmsmethods and have algorithms usually studied, have andusually there st areudied, separate and studiesthere are on separate power and studies commu- on nicationpower and regarding communication cyber risks. regarding If critical systemscyber risks. such If as critical the power systems system such communication as the power infrastructuresystem communication have cybersecurity infrastructure risks, have that cancybersecurity have severe risks, consequences that can have and traditionalsevere con- riskssequences are now and included traditional in risk risks assessments. are now incl However,uded in risk SG communicationassessments. However, systems securitySG com- ismunication a relatively systems new topic; security few academic is a relatively and experimental new topic; few studies academic have been and found experimental [13]. studies have been found [13]. Energies 2021, 14, x 2657 FOR PEER REVIEW 3 3of of 38 36 FigureFigure 2. 2. SGSG Cyber-Security Cyber-Security Sy Systemstem Structure Structure and Relationship Diagrams. AA general general assessment assessment of of the the vulnerabilities vulnerabilities can split into five five categories: •• InteractionInteraction control control framework framework security; security; •• SmartSmart meter meter measurement measurement security; security; •• AssessmentAssessment of of power power system system status security; •• IntelligentIntelligent network network communication