The smart grid is one of the most significant applications of the Internet of Things (IoT). As information and communication technologies (ICT) developed and applied in traditional power systems, the improvement of smart grid cyber-physical-systems(CPS) increases too. IoT-based smart grid systems are critical infrastructures, also they have complex architectures and include critical devices. They contain communication systems that can lead to national security deficits, disruption of public order, loss of life or large-scale economic damage when the confidentiality, integrity, or availability of the communication is broken down. These huge systems may be vulnerable to cyberattacks. Therefore, there is a lot of research effort to enhance smart grid security in industry, government, and academia. The security approaches are important to improve solutions against cyber-attacks in smart grid applications. We present a comprehensive survey supported by a wide review of earlier work. Additionally, recent advances and countermeasures are presented on smart grid cyber-security. In this paper, the threats and potential solutions of the IoTbased smart grid are analyzed. We focus on cyber-attack types and provide an in-depth of the cyber-security state of the smart grid. Particularly, we concentrate on the discussion and examination of network vulnerabilities, attack countermeasures, and security requirements. We aim to supply a deep understanding of cyber-security vulnerabilities and solutions and give a guide on future research directions for cyber-security in smart grid applications.

Introduction

Internet of things is the revolution of the Internet and machine-to-machine (M2M) communication. IoT means connecting different devices via the Internet or IP-based solutions. There will be 28.5 billion networked devices by 2022 [1]. A device can be anything like fridge, sensor, air-conditioner, mobile phone, car, personal computer, laptop. Devices can be already connected via non-IP solutions on a small scale. IoT aims to connect all kind of devices through IP-based solutions at a large scale, too [2]. In an IoT network, devices can interact or communicate directly or through a gateway by IP addresses over the Internet [3]. There are a lot of IoT applications such as intelligent transportation, pollution monitoring, smart cities, smart buildings, connected healthcare [2]. The biggest IoT application is smart grid [4]. It has two lines called power line and communication line. The communication line is very important in terms of intercommunication [5]. A smart grid system, from energy generation to the consumer, is equipped with bidirectional smart devices, such as sensors, actuators, and smart meters [6]. This enables to provide a real-time balance, monitor, and control, anywhere and anytime at high granularity and accuracy [7].