A Survey on IoT-Enabled Smart Grids: Technologies, Architectures, Applications, and Challenges

Abstract

The state of the power system has changed over the last decades. Recently, the power system has faced several challenges and issues. On the one side, demands for electrical energy are increasing day-by-day, with power losses, grid failure, and lack of smart technology; on the other side, security threats are also increasing. The current power grid cannot deal with these issues. The Internet of things (IoT) has grown quickly in a very short time because of its main features. By using IoT in the power grid, we can enhance the conventional grid’s efficiency, capacity, reliability, sustainability, scalability, and stability. Using the IoT in smart grids resolves the numerous problems faced by current smart grids. According to the latest research on IoT-enabled smart grid (SG) systems, security issues have been identified as one of the key problems. This paper reviews the different security aspects and applications while integrating the IoT with smart grids and discusses various frameworks. Apart from this, we also focus on various IoT and non-IoT technologies used in the smart grid network, such as sensing, communication, and computing technologies, as well as their standards.

1. Introduction

The larger part of the world’s power plants uses fossil fuels for power generation. The world’s fossil fuel reserves are being reduced and will likely run out shortly. For human survival, the availability of the necessary electrical energy must be maintained. As a result, the smart grid is the finest solution available. A smart grid solves the existing problems of traditional grids, and it deals not only with power transmission but also monitors and manages energy usage. Since the invention of electricity, power grids have evolved regularly. Despite the electrical grid’s essentially unchanged structure over the years, new technologies have emerged. In this context, one of the most significant issues is figuring out how to use contemporary information and communication technologies (ICTs) to enhance power grid reliability, stability, and power efficiency while also satisfying a wide range of consumer needs. Renewable energy sources such as solar and wind, as well as home energy production, are a growing trend. Unlike the traditional power grid, these kinds of energy supplies have much less centralized infrastructure, and they may not be as unpredictable in the long run. These requirements have a direct impact on the performance of the electric power grid, necessitating the use of cutting-edge ICTs for widespread monitoring and control [1]

The current electricity infrastructure is based on digital technology that is used to supply electricity to consumers, called the smart grid [2]. The earlier power system was centralized in nature, and the job of the previous system was to generate, transmit, and deliver electricity. There was no security mechanism in traditional infrastructure; the traditional system worked well until the last century. However, the power demands are increasing, smart appliances are growing day-by-day, physical and cyber security is essential, and reliability and efficiency are mandatory; so, due to changes in the entire infrastructure, the smart grid came into existence [3]. The smart grid offers a bi-direction flow of energy between the service provider and the consumer. It involves several devices that monitor and control the grid.

The problems of connectivity, automation, and monitoring are solved by using the IoT with a smart grid. IoT devices such as sensors, actuators, and smart meters contribute significantly to the whole smart grid infrastructure [4]. IoT helps the grid in preventing and reducing damage at the time of a natural disaster, and along with reducing economic losses, it improves the reliability of power transmission [5]. Utilizing the IoT technologies in the power industry typically consists of three fundamental steps, the first of which is the digitalization of the assets, the second of which is collecting the asset data, and the third of which is developing computational algorithms in the control systems (for example, in the edge of the cloud). In this context, telecommunication infrastructures must have a guaranteed quality of service (QoS) and be compatible with industrial protocols and particular security requirements in the smart grid [6].

The key goal behind the IoT is “To connect the unconnected. Within a decade, it has revolutionized the way humans live. IoT provides its services in every area of human life, such as medical, agriculture, transport, Smart City, Electric Grid, environmentally friendly, etc. [7]. The main idea behind the IoT is to connect whole devices to the Internet. In the IoT, all devices and objects have a sensor and are connected to an IoT platform [8]. IoT-enabled smart grid technology provides an impressive network between the public and machines through all types of information sensing devices Radio Frequency Identification (RFID) devices, infrared sensors, Global Positioning System (GPS), smart security systems, laser scanning, etc.), coupled with existing network infrastructure. IoT covers all domains in smart grid infrastructure, i.e., the generation, transmission, and distribution of electricity, and so on. In the power generation part, it monitors the power generation area, power unit, distributed power plant, pollutants and gas emissions, energy consumption, coal contents, power prediction, energy storage, power connection, and so on. In the transmission section, it monitors the entire power transmission line. It protects the energy tower in the transmission line and is also widely used in intelligent substations, network control, condition tracking, service and equipment management, and so on. The main use of IoT is in the distribution part because the consumer side is involved in this part. In the IoT-enabled smart grid system, the smart meter plays a vital role. In addition to smart meters, IoT is used in multi-network convergence, electric vehicle charging, control and maintenance of energy efficiency, power demand management, etc. [9].

The power grid is critical for converting energy from energy sources to all activities necessary for economic development. The future power infrastructure that will support sustainable development is critical. A well-functioning smart grid can help reduce carbon emissions from energy sources, increase efficiency in energy conversion and end-use processes, and promote environmentally friendly mobility [10].

1.1. Motivation and Contribution

The rapid growth of technology in several IoT industries has created new chances for the smart energy grid system’s smooth operation. Hence, the number of smart devices increases day-by-day, and the demand for electricity has also increased. Alternatively, security issues have also arisen. Thus, different smart technologies are getting involved in managing electricity demand and supply and securing the overall infrastructure. IoT is one of the powerful technologies that solve the smart grid system problem. The IoT has the capability to provide a wonderful solution to the current issues of transforming a conventional power grid into a modernized smart power grid. The adoption of IoT technology is growing in popularity for current smart grid applications in residential buildings and commercial buildings as well. The integration of sensors and smart metering in a smart grid will allow for more efficient functioning at all stages of energy production, transmission, and distribution, resolving most of the electrical industry’s problems.

There is a lot of research happening now in this sector. This paper will help the researchers briefly understand the IoT, smart grid, IoT-aided smart grid architecture, prototypes, multiple IoT and non-IoT technologies, applications, and security issues. The key contribution to this review is as follows:

• In this survey, we critically review the existing literature on IoT-enabled smart grids and compare it with our survey, which is listed in Table 1;
• We give a brief overview of the IoT along with the smart grid and briefly discuss the technologies, architectures, prototypes, and communication technologies of IoT-enabled smart grid systems;
• We illustrate the IoT applications in smart grids, security issues, and challenges of adopting these two technologies.

1.2. Organization

This paper is organized as follows:

• Introduction, motivation, and contributions are discussed in Section 1;
• We discussed the literature survey part in Section 2;
• We provide a brief discussion on different aspects of IoT and Smart Grid in Section 3;
• Section 4 discusses the different types of IoT-enabled smart grid architectures and prototypes;
• Numerous IoT and non-IoT technologies involved in smart grid infrastructure are discussed in Section 5;
• IoT applications in smart grid are discussed in Section 6;
• Security issues and challenges in adopting IoT technologies in smart grid are discussed in Section 7;
• Finally, the paper concludes in Section 8;
• A pictorial representation of the organization of the paper is shown in Figure 1.

2. Literature Surveys on IoT-Enabled Smart Grid Systems

Several surveys have been conducted in the domain of IoT-enabled smart grids. In all these surveys, authors discussed various aspects of IoT-enabled smart grids, e.g., architecture, technology, applications, and challenges. In some surveys, the author does not discuss existing work; some authors did not mention technology in brief, and some missed the challenges.

In this paper [11], the author analyzes IoT research on energy systems, including cloud computing and data analytic platforms. The author also covered the privacy and security concerns associated with IoT deployment in the energy sector, as well as some potential solutions, such as blockchain technology. In this paper [12], the author presents a survey on smart grid technology, but there needs to be a proper discussion of IoT-aided smart grid’s in previous work and its different architecture. This paper [13] provides a summary of past research in this field, focusing on the benefits and applications of IoT technology within the context of smart grid systems. The author also explores the potential for the IoT at each layer of the architecture, which clarifies the function of and connections between individual technologies. In this paper [4], the authors conducted a literature review of IoT-aided smart grid systems, including existing architectures, applications, and prototypes. In this paper [14], the author performed a thorough and critical study of the IoT for business applications and smart energy systems. The author also discussed IoT applications in business, smart energy, data communication networks, energy production, and endpoint equipment. In this paper [15], the author presents the energy internet concept for utility energy service and demand-side management, along with its key components and difficulties, which are described to pinpoint the current research needs in the area. The author also offers a thorough analysis of how Internet-based energy management systems can enhance operational and managerial sustainability in the future. The authors of this paper [16] give a complete study of energy-efficient communications and computing methods in smart grids. Considering recent developments in 5G communications and edge computing, the author also discusses critical questions and research obstacles. In this study, the author [17] investigates the IoT-enabled smart grid and its recent practical advancements. Additionally, this author investigates and classifies smart grid IoT security risks. The author of this study [18] outlines how to extend the present security standards for power grids to time-sensitive networking and offers some insights into the current standards. Paper [19] presents a survey about IoT and smart grids and their relationship, and discusses a few applications and challenges. This paper does not properly discuss the different types of IoT-aided SG architecture and its backbone technology. In this paper [20], the author reviews the technology behind the IoT-enabled smart grid, including its architecture, application, and security issues. Paper [21] gives a review of the different technologies of IoT-based smart homes. The author also discusses different computing technologies and software parameters in this paper. The author of this paper [22] examines the use of IoT in the development of smart buildings. In this survey [23], the author discussed the most important studies on IoT applications for smart grids. This study also discusses numerous new methodologies utilized in IoT and smart grids, as well as their respective applications in various sectors. The author of this study [24] discusses the Internet of things (IoT) with energy-harvesting subsystems and the most recent design approach for harvesting systems, distribution plans, storage innovations, and control systems. The author also highlights the future design challenges of IoT energy harvesters in distributing energy consistently. This study [25] presents an innovative approach to properly measure and compare the adoption of IoT technologies in the energy sector. Additionally, the author examines energy platforms from each hierarchical level of their architecture, expanding and updating prior work. This paper [26] includes in-depth details on how 5G cellular networks are influencing the growth of the IoT and power systems. The concept and architecture of power and the IoT are discussed in this paper.

Here are several surveys on the IoT-enabled smart grid that centered on the overview, architecture, challenges, and applications. Many surveys focused on applications whereas some focused-on architecture. Some surveys focused on security issues. In our survey, we have addressed all key components of IoT integration with the smart grid, such as an overview of IoT and smart grids, communication technologies, integration, application, architecture, prototypes, and different challenges. We have briefly discussed the role of IoT in smart grid infrastructure, prototypes of IoT-enabled smart grid systems, covered all IoT and non-IoT communication technologies, and provided a detailed discussion on the application, issues, and major challenges of IoT integration with smart grids.

Table 1. Comparison with a related survey of the IoT-enabled smart grid.

Author	Publication Year	Contributions
Goudarzi et al. [17]	2022	This paper mainly focuses on the architecture and different security aspects of the IoT-enabled smart grid.
Zahra and Maryam [13]	2022	This paper provides the set of measures required for the realization of IoT-enabled SG and applied an industrial IoT layered approach.
Parvin et al. [15]	2022	The focus of this study is the energy internet approach for utility energy services and demand-side management.
Mao and Zhao [16]	2021	IoT energy efficiency development, notably in communication and processing, was covered in this study.
Lázaro et al. [18]	2021	This survey identifies smart grid communication vulnerabilities and shows how IEC 62351-6 security methods can be used for time-sensitive networking.
Tanveer and Dongdong [14]	2021	This paper analyses IoT business applications and smart energy systems.
Adnan et al. [20]	2021	This paper reviews the technologies behind IoT-aided smart grid systems and their application and security issues.
Sherali et al. [24]	2020	This paper examines IoT and energy harvesting, encompassing control units, storage systems, distribution techniques, harvesting systems, and new challenges.
Miguel et al. [25]	2020	This article contrasts energy frameworks with the degree of IoT, a measure of how IoT technologies are used.
Jinsong et al. [26]	2020	This paper discusses 5G’s importance, impacts, and issues in the power IoT.
Nase et al. [11]	2020	This paper categorizes various IoT use cases in the energy sector, from power generation to the end user.
Alireza [19]	2019	This paper focuses on the relationship between the IoT and smart grid, applications, and challenges
Yasir et al. [4]	2019	This paper overviews the different aspects of IoT integration with smart grid systems.
Qiang [12]	2019	This paper deals with applications, issues, and future research of IoT-aided smart grid systems.
D. Mocrii et al. [21]	2018	This paper mainly focused on major technologies behind IoT-aided smart grid systems.
S. Sofana and Tomislav [23]	2018	This review article presents the most important studies on IoT applications for smart grids.
This Paper	-	This survey is centered on a brief introduction to the IoT and smart grid system, architecture, prototype, IoT and non-IoT technologies, applications, and security issues.

shows a summary of some of the latest surveys happening in the field of the IoT-enabled smart grid.

3. Descriptions of IoT and Smart Grid Technologies

This section will discuss the IoT and the smart grid network. We cover different aspects of IoT and smart grid technologies, e.g., architecture, technology vision, and barriers.

3.1. Internet of Things

The IoT offers an innovative, fully connected “smart” world as the relationships between objects, their atmosphere, and humans become closer to each other [27]. In 1999, British technology pioneer Kevin Ashton coined the term “IoT” to describe a system in which sensors and actuators connect physical objects to the Internet. Within a decade, the IoT has become very popular, with Internet connectivity and computing capabilities extending to a range of objects, devices, sensors, and daily items. Generally, the term IoT does not have a single or standard definition. IoT generally indicates the circumstances where network connectivity and computing power extend to objects, sensors, and other devices that are generally not considered computers, enabling these devices to produce and share data with a minimum amount of human participation [28].

3.1.1. The Visions of the IoT

• Internet oriented: The objects which are involved in IoT should be smart objects, and all objects use the IP protocol specification.
• Things-oriented: Using sensors and pervasive technologies, we can track any object and an electronic product code can uniquely identify that object.
• Semantic-oriented: For better representation, the raw data must be managed because numerous sensors provide a huge amount of data [29].

3.1.2. Characteristics of the IoT

• Fully aware: Sensors provide information from objects anytime and anywhere.
• Reliable transmission: Web and communication networks transmit accurate and real-time data.
• Intelligent processing: Cloud computing systems are used for the study of large volumes of data for controlling objects [30].

3.1.3. The Key Technology of IoT

Numerous technologies are involved in the execution of IoT systems, such as radio frequency identification (RFID), Wireless Sensor Networks (WSN), infrared sensors, global positioning systems (GPS), Internet and mobile networks, etc. Among these technologies, we will focus on some of them.

• RFID Technology

This is the IoT’s most important technology and performs a significant role in the IoT’s development. It contains applications for data acquisition and a back-end database network and includes one or more readers and multiple RFID tags. To send data, it uses a radiofrequency electromagnetic field. The RFID tags are attached to this, which stores the data. Apart from this, RFID provides real-time object monitoring. The RFID tags antenna receives signals from RFID and returns them to RFID with some additional information.

• WSN network

WSN networks have five layers: the physical layer, network layer, MAC layer, transport layer, and application layer. The physical layer deals with the WSN sink and the physical parameters of node communication. Physical parameters demonstrate which band to be used and the modulation and demodulation of the signals. In the MAC layer, the loading of each node is defined, which deals with transmitting and receiving beacon signals, queries, associates, and different information regarding the completion of its own network description. The network layer gives complete information about the route, and by using different protocols, it sends and receives the packages. The main job of the transport layer is to deal with reliable packet transmission and provide an interface to the application layer. The application layer integrates node data collection after analysis to fulfill the computational requirements of various applications [31,32].

3.1.4. Architecture

The main components of IoT are sensors, RFID readers, WSN, cameras, and various data collection terminals, which are responsible for data collection and delivery in the same way human sensory organs work [33]. An IoT system has three levels of architecture: devices, gateways, and IoT clouds. The data moves via these three levels by using four different transmission channels (device to device, device to gateway, gateway to cloud, and between clouds). Figure 2 shows the architectural diagram of the IoT.

3.2. Smart Grid

The smart grid came into existence to solve the challenges that arise in the traditional grid. On the one hand, it increases the demand for electrical energy. Alternatively, it decreases the chances of energy wastage and solves the problems of efficiency, effectiveness, reliability, security, and stability. The smart grid is a revolution in the energy sector. Earlier grids are centralized in nature, but the smart grid is deployed in a decentralized method where energy flows in both directions between the service provider and consumer. Smart grids have four subsystems: generation, transmission, distribution, and consumption of electricity, and three types of networks, i.e., HAN (home area network), NAN (neighborhood area network), and WAN (wide area network).

HAN is deployed on the consumer side, and it connects the electrical appliances with smart meters. HAN includes smart devices, home appliances, and electric vehicles, along with renewable energy sources. It also manages the consumer’s on-demand power requirements. The main job of a NAN is to gather information about service and metering from several HANs and then transmit it to the data collectors that connect NANs to a WAN. A WAN serves as the backbone for network gateway communication. The main objective of a WAN is to promote cooperation among energy transmission systems, mass generation systems, renewable energy sources, and control centers [34,35].

The smart grid works well in incorporating distributed generation into the traditional centralized power system. It provides a link within a power system between consumer devices and traditional assets. The key characteristics of smart grids are self-healing, consumer-friendly, business-supporting, asset management, efficient operation, and attack resistance. It also provides power efficiency for current time needs and is capable of adjusting to all generation and storage options [10]. Figure 3 shows the architectural diagram of the smart grid, which comprises four main subsystems, i.e., generation, transmission, distribution, and consumption of the power system.

3.2.1. Smart Grid Attributes

• Efficient: It fulfills the consumer demands for increased power supply without adding extra infrastructure.
• Quality focused: The smart grid is focused on providing reliable electricity that is free of disruption and interruptions.
• Opportunistic: This creates new opportunities and a new market by allowing plug-and-play innovation to be capitalized wherever and whenever necessary.
• Resilient: Due to its decentralized nature, it increased the resistance to threats and natural disasters and strengthened controls on the smart grid.
• Environmental Improvement: Because of changes in the global climate, it provides a meaningful route toward the remarkable development of the environment as the result of electric power.
• Motivating: It enables real-time communication between consumers and utilities so that consumers can control their energy consumption on the basis of their price/environmental preferences.

3.2.2. Barriers to Smart Grids

• Security: Due to the integration of information technology in the smart grid, cyber security vulnerabilities and different types of security threats come into the picture.
• Privacy: In smart grids there are different smart devices, and those smart devices produce a huge amount of data, so the risk of potential consumer privacy violations increases.
• Stakeholder Engagement: Smart grid implementation is at an early stage, so stakeholders have negative perceptions of this technology. So, all doubts of stakeholders must be clarified and the benefit of each part of the smart grid to the consumers must be explained.
• Cost: The initial cost of implementing a smart grid is costly; consumers have difficulty accepting and adopting smart grids [36].

3.2.3. Smart Grids vs. Traditional Grids

The traditional electric grid is a combination of transmission lines, transmission substations, synchronous machines, power transformers, distribution lines, distribution substations, and different types of loads that are all interlinked. They are placed far from the energy consumption area and obtain electricity via massive transmission lines.

The smart grid is a more efficient and effective version of the traditional electrical infrastructure. It is, after all, a two-way communication between the utility and the power consumer. The smart grid can keep track of grid-connected system activities and user power choices and provide real-time data on all activities. Smart appliances, smart meters, smart substations, and advanced synchro phasor technologies are all major elements of the smart grid. The comparison between smart grids and traditional grids is discussed in

Table 2. Comparative study between smart grids and traditional grids.

	Smart Grid	Traditional Grid
Technology	Digital	Electromechanical
Generation	Centralized and distributed	Centralized
Monitoring	Self	Manual
Distribution	Two-way distribution	One-way distribution
Restoration	Self-healing	Manual
Equipment	Adaptive and islanding	Failure and blackout
Topology	Network	Radial
Control	Pervasive	Limited
Reliability	Predictive	Estimated
Operation and Maintenance	Monitor equipment remotely	Check equipment manually
Customer Interaction	Extensive	Limited

.

4. IoT-Enabled Smart Grid Architecture and Prototypes

In this part, we mention different IoT-enabled smart grid architectures and various available IoT-enabled smart grid prototypes.

4.1. IoT-Enabled Smart Grid Architecture

Numerous architectures are available for IoT-enabled smart grid systems; three-layered architecture, four-layered architecture, the smart grid architecture model, cloud-based architecture, web-enabled smart grid architecture, and last meter smart grid architecture. We will discuss a few of them.

4.1.1. Smart Grid Architecture Model (SGAM)

The smart grid Architecture Model (SGAM) is an important deliverable of the reference architecture working group of the EU Mandate M/490. It provides a framework for developing smart grid architecture by outlining a collection of core concepts and perspectives, as well as a technique for mapping use-case data. The SGAM comprises five layers: business, function, information, communication, and component. These levels are called interoperability layers. Each layer of interoperability has a smart grid plane, which comprises electrical domains and information management zones. This model’s primary objective is to depict which domains interact with one another over which information management zones. A five-layer cube-like representation is shown in Figure 4. SGAM can be divided into SGAM smart grid planes and SGAM interoperability layers for easier comprehension [37].

• SGAM Smart Grid Planes

The main view of an SGAM architecture visualization is a smart grid plane. On one side of each plane are the domains of the energy conversion chain, and on the other are the hierarchical zones for managing the power system. Generation, transmission, distribution, and DER are among the energy conversion domains. Customers are the people who use the electricity and those who produce it. The management of electrical processes is broken down into a number of hierarchical zones. These zones are as follows: process, field, station, operation, enterprise, and market.

• Interoperability Layers

Interoperability is a necessary prerequisite for smart grid systems and components that interact with one another. SGAM has five interoperability layers: business, function, information, communication, and component. The business layer addresses the business-related components of smart grid’s information exchange and focuses on functional departments, business processes, and organizational capabilities. The function layer shows how functions and services relate to each other from an architectural perspective. The information layer covers how information is shared between services, functions, and components. The communication layer comprises several protocols and methods that enable the exchange of the objects described in the information layer. Furthermore, the component layer includes physical components (assets, devices, and grid equipment) and actors (operators and aggregators), which share information objects and protocols to assign functions.

4.1.2. Three-Layered Architecture

The three-layer IoT-enabled smart grid architecture (application layer, network layer, and perception layer) is shown in Figure 5 and has been proposed in [4,33,38,39].

• Application Layer

This layer makes the power grid better and smarter. The main job of this layer is to collect data from the network layer and on the basis of these data; it tracks and troubleshoots IoT-based appliances and smart grid systems in real-time.

• Network Layer

The network layer is based on various telecommunication networks. Its main job is to map the information that the perception layer collects to the telecommunication protocol and then transmit that data to the application layer. We must choose the low-cost and less power consumption types of the network because of the establishment of a short-distance network. We will also concentrate on increasing the wireless sensor network functionality.

• Perception Layer

Different sensors are used to control the entire power network, such as speed sensors, temperature sensors, pressure sensors, voltage, and current sensors. The main purpose of using these sensors is to monitor the smart grid and link them with all equipment that is used in the power system. These sensors provide real-time information and that information is sent to the management system for analysis purposes, and if an emergency arrives, it will take action.

4.1.3. Cloud-Based Architecture

The problem with fossil fuels is that their cost is always varying, and they have a bad effect on the global environment’s ecostability. It is mandatory for us to discover new sources of renewable energy and enhance energy efficiency on the consumer side through smart grids of different buildings. For global sustainability, the efficiency of the buildings’ energy must be improved. This is why smart energy is a prominent IoT study area.

The author has presented an IoT architecture with smart location-based automated and networked energy control using mobile platforms and cloud computing technologies in this research [40], which allows multi-scale energy proportionality, including building user and organizational proportionality. In the smart grid, static energy management has given way to dynamic energy management, and centralized control modes have given way to distributed energy control. Its architecture is composed of various buildings.

Figure 6 shows the framework of cloud-based architecture, and the main components of this framework are (i) multisource energy saving policies, (ii) mobile device-based monitoring and control, (iii) smart location-based automated energy control, and (iv) cloud computing and storage [4]. Every part of the organization (office, building, campus, home, etc.), has its own policy to control energy consumption. Therefore, these policies of different levels are added to the location-based automatic control scheme. The policy hierarchy is shown in the figure. It looks like a tree architecture for the control plane of a building wherein the energy-saving policies that cover different levels are enforced by policy servers. Through smart devices (smartphones, tablets, laptops, etc.), the user is connected to the Internet.

In the last decades, the smartphone has changed human lives. It has several applications. The smartphone has different networking interfaces, i.e., Wi-Fi, 3G/4G cellular networks, and Bluetooth, and it has multiple sensors, e.g., GPS (global positioning system), which can track, regulate, and manage the energy control systems remotely by using these smartphones and modify or change the energy-saving policies. Every smartphone has a feature for location detection. The GPS is enabled on every smart device. The main use of location information is to design automatic control policies. Thus, such control policies can switch ON/OFF energy-consuming devices at home or the office, depending on the position and direction of the use. In the last few years, cloud computing has become very popular. The need for a cloud computing platform in this framework is for the storage of data, modelling, and analysis-based computation. The cloud gives a simple data storage and a retrieval facility for data on energy usage from buildings. Before using the cloud framework, the system must be designed and integrated according to this cloud environment [4,40,41].

4.1.4. Web of Things-Based Smart Grid Architecture

The architecture of an IoT-enabled smart grid system based on web-enabled architecture is shown in Figure 7. The web of things is made up of a collection of Internet-enabled embedded devices that employ web services to provide a user interface. To access this, the end user simply needs a computer with an Internet connection and a web browser. Two types of energy sources are used in the smart grid architecture. First, non-renewable energy sources, which have a huge carbon footprint on the planet, are the most common sort of energy source. The second type of energy source features a variety of eco-sustainable and renewable sources of energy [42,43,44].

Non-renewable energy sources include nuclear power stations and thermal power stations, whereas renewable energy sources include wind turbines, solar panels, biogas facilities, and electricity generated from biofuel. The energy sources are connected to individual digital energy meters with standard specifications. These digital energy meters gather data on home energy usage. The meter readings are collected using Internet-connected embedded devices that are constantly in contact with the meter. Regularly, the data collected by the meter are uploaded to the server. On top of these embedded system devices, this server provides web services that comprise the web of things. A user only needs a username and password to use all these services from any computer connected to the Internet. The energy sources for each household are controlled with the use of source changers [44].

4.2. Prototypes for IoT-Enabled Smart Grid Systems

Before the implementation of IoT-enabled smart grids, we should examine several functions and confirm their operation. In the development of this development, these prototypes play an important role. Several prototypes are available for IoT-enabled smart grid systems. Some work well and a few of them need more advancement. We will discuss a few of the available prototypes.

4.2.1. Simple Prototype for Energy Efficiency

A smart device (a phone, tablet, or laptop) in this prototype, including a location sensor, transfers its location to two servers at a given period in two locations. Using this prototype, a user can dynamically monitor and handle appliances at different locations. The electrical appliances were linked in office buildings in both locations, e.g., residence and workplace. After any changes in users’ location, the prototype permits the server to activate the energy management mechanism by turning ON/OFF the devices in both locations. The consumer can easily enforce his own energy policies and track them in real-time by using this prototype [45].

Figure 8 shows the prototype structure. Kill A Watt electrical meters [45], WeMo controllers [46], Wi-Fi routers, one server for each location, smart devices with location sensors, and a GlobalSat GPS module are the hardware needed in this prototype, whereas that prototype requires two different packages of software. One package is used to handle GPS location data recordings and sends that information to the server in a compliant format as NMEA 0183. The second package is based on Wi-Fi routers, which configure and manage the software. In addition, it offers port mapping features for outside network address translation access to the server [44].

4.2.2. Integration of Renewable and Non-Renewable Energy Sources at Home

A model was developed using the IoT for integration between renewable and non-renewable sources of energy at home, and this prototype is developed for the home area network (HAN) architecture, which is shown in Figure 7. The electric meter used in this prototype records voltage and current measurements, which are connected to non-renewable energy sources and renewable energy sources. IoT-embedded devices have a direct connection; they can change the energy source. This prototype also has a web service feature that allows consumers to keep track of daily, weekly, monthly, and annual energy consumption. Consumers can also design and plan the transfer from non-renewable to renewable energy sources in advance [43].

Different hardware and software components are required for this prototype. The required hardware is an ARM Cortex M3 Processor, an LPC1768 processor from NXP, CMSIS, an LwIP protocol stack, MAX232 ICI, an RS232/485 Port, an Ethernet port RJ45, an LPC1768 processor, etc. Whereas in the case of software requirements, a graphical user interface (GUI) is used to connect Internet services and user account administration [47,48].

Some existing prototypes are also available, e.g., real-time medium voltage grid control, in-home appliance monitoring implementation, and web of things-based smart grids [49].

5. Communication Technology Required for Smart Grid Integration with the IoT

Multiple IoT and non-IoT communication technologies are involved in the integration with the smart grid. These technologies are required for data transmission between devices, and the communication between devices will be based on wired and wireless technology. On one side, the smart meter communicates with IoT devices; on the other, it communicates with the utility control center. Information was between these two sides through a smart meter. A communication network must be reliable, secure, and cost-effective. A few of the IoT and non-IoT technologies are as follows.

5.1. IoT Communication Technology for Smart Grids

Regarding integrating the IoT and the smart grid, there is a range of wireless technologies to consider, i.e., MQTT, 5G technology, Bluetooth, NB-IoT, 6 Low-PAN, Z-Wave, Wireless HART, and ZigBee. In a smart grid, M2M communication is needed for control and monitoring of the entire grid infrastructure. The smart grid requirements of M2M communication are fulfilled by 5G, an emerging technology. It has advanced features of communication with a large range of objects that have the capability to sense and perform some mechanical actions. It is secure and it solves the problems of latency, reliability, scalability, and flexibility in terms of bandwidth, data rate, and coverage. It works on various frequency bands, authorized and unauthorized, e.g., below 1 GHz, below 6 GHz, and above 6 GHz [50].

Table 3. IoT communication technology used for smart grids.

Protocol	Advantages	Disadvantages	Application Area	Data Range	Coverage Area
MQTT	Reliable, lightweight, efficient, and simple implementation	Limited scalability, latency issues, and unencrypted	Home automation, smart cities, and remote sensing	256 Mbps
OPC-UA	Platform independence, unified access, reliable, and secure	Overcomplexity, interoperability, and object orientation	Industrial automation, production, and processing platforms	--	--
Z-Wave	Simple installation, interoperable, reliable, low latency, and scalable	Short range, less speed, a limited number of nodes, and not appropriate for NAN/WAN	Home automation	100 kbps	30 meters
5G	Speed, reliability, and bandwidth are high, and latency is low	Low range, high cost, and security issues	Monitoring and control	Up to 20 Gbps	Up to 100 meters
ZigBee	Low power usage, scalable, simple, and easy	Low data rates and processing, short range, poor battery, and unsecure	Energy monitoring, smart metering, and home automation	250 kbps	10 meters
Bluetooth	Less power consumption and cost-effective	Short range and low data rate, less bandwidth, and security issues	Home automation	Up to 1 Mbps	Up to 50 meters
6LowPAN	Robust, less power, and better network topology	Short range and the data rate is less	Smart metering and home automation	250 Kbps	Up to 100 meters
Wireless HART	Widely used, scalable, and cost-effective	Less data rate, low range, security issues	Smart metering and power generation	115 Kbps	200 meters

summarizes the IoT communication technologies used in smart grid systems.

The MQTT protocol is an open standard that is based on TCP/IP. MQTT is an abbreviation for "message queuing telemetry transport." It is a protocol that is utilised mostly for the purpose of connecting devices to one another and to backend services over the internet. The Internet uses TCP/IP, which was developed on top of the TCP/IP stack, while the IoT uses MQTT. In MQTT, the publisher, subscriber, and broker are the three key actors. Brokers facilitate the sending and receiving of messages between publishers and subscribers based on the subject. These brokers validate each other's credentials to ensure that the TLS protocol is a safe and secure method of communication. Since MQTT does not require a large amount of bandwidth, it is ideally suited for usage with remote sensors. However, there are a number of disadvantages to using MQTT with limited devices. Because of the large string subject names, MQTT is unsuccessful in low rate WPAN applications [33,51].

OPC stands for open platform communication. It is one of the most significant communication standards for IoT. For efficient and reliable data transfer, the OPC interoperability standard is employed in the industrial automation field, as well as in other sectors. OPC was created by the OPC Foundation to reduce the amount of redundant work required from hardware vendors. This was achieved by simplifying the communication protocols used by manufacturing applications and devices within the scope of more complicated distributed control systems. It supports data exchange between SCADA, HMI, PLC, and many other critical systems. OPC originally refers to process control via object linking and embedding (OLE). Its primary function is to facilitate continuous monitoring and control of production processes. The “UA” in OPC UA refers to “Unified Architecture,” the most recent specification of the standard. It differs from OPC in that it is platform-independent. It uses binary TCP/IP or SOAP instead of COM/DCOM. Semantic data definition is made possible by OPC UA along with other enhancements. OPC-UA is gaining popularity due to its platform independence, which allows it to be used with operating systems other than Microsoft Windows, such as UNIX. Because OPC-UA is built on web services and is centered on service-oriented architecture (SOA), it makes it simpler to establish OPC connections in a network context, and it is designed to promote application compatibility. Both of these benefits are meant to increase productivity. OPC UA has also enhanced security features such as encryption, authentication, and audition [52].

Bluetooth is a wireless communication network leading to low-capacity, short-range communication, known as IEEE 802.15.1. Since the evolution of this technology, it has been upgraded from time to time. At first, it worked on point-to-point communication from one device to another; now, it connects many devices to many others at the same time. It gives a data rate of 721 Kbps and works on the 2.4–2.4835 GHz unlicensed industrial, scientific, and medical (ISM) band. The coverage of the Bluetooth network is between 1m and 100m, based on the communication design. In the IoT, Bluetooth low-energy (BLE) is primarily used to set the stage for future applications. BLE mainly targets small-scale IoT applications, such as wearables and broadcasting beacons, which require devices to transmit a limited volume of data using lower energy. In 2017, a new upgraded version of the Bluetooth “mesh specification” came. It standardizes the theoretically unlimited many-to-many functionalities of BLE. The prior Bluetooth topologies mainly operated on people and devices, but this mesh topology-based system fundamentally works on how devices interact with each other. This is all about various devices communicating with several other devices [53].

Z-Wave is designed for small data packets to provide secure and low-latency transmission, with data rates up to 100 kbit/s. This is very suited for sensor and control applications. It is a well-known wireless protocol used in the home area network. Because Z-Wave is not an IP-compatible protocol like Wi-Fi, Z-Wave devices will never be able to connect to the Internet or even other specific user devices (smartphones, laptops, etc.). It requires a controller that acts as a gateway to track and control all devices and allows interaction between smartphones or with Z-Wave devices through the Internet or any other local network [54]. The 6LowPAN network runs on the standard IPv6 protocol suite based on IEEE802.15.4 and allows 6LowPAN network self-organization with a routing protocol. The protocol IPv6 is chosen as the networking technology. It explained how IPv6 could be used in addition to low power, data rate, and cost of personal network connectivity. The focus of 6LowPAN is on applications that require wireless connectivity at low data rates, such as those with a limited form factor [55]. Zigbee technology is based on IEEE 802.15, a wireless sensor network that defines a series of protocols with less power, rate, and cost, and has less time delay characteristics. It is easy to build and deploy, offers robust protection, and gives more data reliability. In addition, it transfers data at a low rate of about 250 kbps. It is, therefore, very useful for applications that need a low data rate [56].

5.2. Non-IoT Communication Technology for Smart Grids

Numerous non-IoT technologies are required for smart grid implementation. Some of them are wireless, and some are wired. The wireless technologies used in the smart grids are cellular communication, mobile broadband wireless service, wireless mesh, WiMAX, digital microwave technology, etc. The wired technologies are PLC (powerline communication), optical communication, digital subscriber lines, etc.

Table 4. Non-IoT communication technology for smart grids.

Protocol	Advantages	Disadvantages	Application Area	Data Range	Coverage Area
WiMAX	High data rate, multiple users, and cheaper	Power-consuming and high cost	Smart meter, outage detection, and restoration	75 Mbps	1–50 km
Cellular communications	High capacity, less transmission power, and robustness	Network congestion, handover is needed and security vulnerabilities	Monitoring and management and SCADA	60–240 Kbps	10–50 km
Powerline communications	Cost-effective and low installation Cost and wide availability	Noisy and signal disturbance and complex	Low voltage distribution and smart meter	2–3 Mbps	1–3 meters
Digital subscriber lines	Speed, data rate, high bandwidth, and security	Unreliable, expensive, and no current standardization	Smart meter	1–100 Mbps	5–28 km
Mobile broadband wireless access	Low latency, high mobility and bandwidth, and secure	Costly and moderate data rate	SCADA	20 Mbps	Up to 240 km/hr

summarizes the non-IoT communication technologies used in smart grid systems.

The cellular network is a communication network distributed over land areas called “cells.” It works within the 824–894 Mhz spectrum range. In the smart grid, the cellular network is popularly used in SCADA remote distribution substation system, tracking, and remote DERs metering in the smart grid. WiMAX (world interoperability for microwave access) is an important part of wireless broadband networking standards based on IEEE 802.16. The range of kWiMAX is large, and it spans several kilometers using licensed or unlicensed Spectrum to provide a communication link. WiMAX 802.16’s range is 10–66 GHz for networking infrastructure, 3.5 and 5.8 GHz bands for fixed networks and 2.3, 2.5, and 3.5 Ghz for mobile networking, and 5.8 GHz in unlicensed Spectrum. The WiMAX smart grid applications include wireless automatic meter reading (WMAR), real-time pricing, outage detection, and restoration [57]. Power line communication (PLC) allows data to be sent over given power cables. One can use both power supply and control/retrieve data at the same time by using this communication technology. It operates in a half-duplex way and has a direct meter link. It transmits 2–3 Mbps of high-speed data from one device to the other. This is the most appropriate communications technology for smart grid deployments [58,59]. A digital subscriber line (DSL) is used for digital data transfer via telephone cables. This can be used in smart grid metering systems. The traditional phone line is used for data transmission purposes in DSL. The DSL provides an interface for home utility smart grid data. This is a robust and economical solution [60].

There are several IoT and non-IoT communication technologies that are involved in smart grid implementation, and the role of these are very crucial. Several communication technologies are used in smart metering systems and are mainly distinguished by the communication channel and are therefore divided into wired and wireless. We have discussed a few of them.

6. IoT Applications in Smart Grid

The IoT is an important tool for implementing smart grids. In the smart grid, various technologies of IoT are supported, and by using these technologies, the smart grid improves its processing, alert, self-healing, recovery from disaster, and reliability. By combining the IoT with the smart grid, we can motivate the implementation of smart terminals, sensors, meters, and other information and communication devices. The IoT in the smart grid deals with state monitoring of devices, data gathering, entire smart grid control, and safety and security purposes.

Figure 9 shows smart grid’s distinct applications in all domains of the IoT. The IoT consists of three main components: data collection, transmission, and processing. The most significant advancement of the IoT is the method of information acquisition, which involves acquiring the positions, the smart devices required, and the data on its characteristic modifications by sensors and other real-time access. The theoretical system of IoT technology in terms of network architecture, work mechanism, and transfer protocol improves as the technology evolves. As a result, the IoT can effectively meet the smart grid requirements. From a technical standpoint, the smart grid’s IoT network function is concerned with these three areas: information collection, transmission, and processing [61,62].

The role of IoT in various parts of the smart grid, i.e., power generation, transmission lines, distribution, and consumption, are as follows.

6.1. IoT in Power Generation

In the generation part, the IoT is used in the power generation part to monitor the production of electricity from various types of power plants, e.g., coal, wind, solar, biomass, etc. It monitors the gas emissions, energy storage, and energy consumption by power plants. The production equipment for power plants is labeled and parallelly structured with the electricity grid. When a device fails or the environment changes, the decision would be made on the basis of a range of data gathered by the collector using IoT technology, and then accurate advance indication and report information will be sent to the appropriate responsible person, such as power plants, distributed power plant monitoring, energy consumption monitoring, monitoring of coal, pumped energy storage monitoring, wind power plant monitoring, factory pollutant monitoring and gas emission monitoring, power forecasting, and energy storage monitoring, through the power plant production monitoring system. Because of IoT technology, the system will be able to monitor state information that is wide-ranging, panoramic, real-time, comprehensive, reliable, and trustworthy [62].

6.2. IoT in Power Transmission

In the transmission part, it protects the transmission lines such as the meteorological climate, snowfall, temperature, fog, and so on. Information about the environmental status, mechanical status, and operational conditions of the tower, transmission lines, and high-voltage electrical components can be detected and monitored by using sensors deployed in numerous places. The transmission lines can be monitored using wireless broadband communication technology to detect and eliminate faults. Under global conditions, it uses a combination of information and communication networks to perform the functions of information processing, transmission, and assessment.

6.3. IoT in Substation

The IoT monitors the operation of substation equipment and provides the environmental safety of substation equipment for operation. With this IoT system, operators at substations, grid operations, and maintenance can monitor regional electricity distribution and consumption in real-time.

6.4. IoT in Distribution, Utilization, and Dispatch

The applications of the IoT in these parts are electricity distribution automation, data collection of consumption, electricity load management, advanced metering infrastructure (AMI), smart home, and SCADA (supervisory control and data acquisition). IoT enables bidirectional interactive services such as intelligent power usage, data collecting, household intelligence, effective family energy management, access to the distributed power supply, and electric vehicle charging and discharging. The IoT can also be used in smart meters at the user end to measure various metrics, intelligent power consumption, network interoperability, and manage energy efficiency and power demand [63].

6.5. IoT in Smart Metering

With IoT’s use in energy production, transmission, and distribution, smart metering is also one of the important sections of IoT’s application in smart grids. Meters can communicate data to energy service providers (ESPs) or cloud services via appropriate interfaces using IoT and cloud-based systems. With the use of IoT in smart grids on a regular schedule, more data can be monitored. As a result, the chances of essential repairs being started in the case of failures will improve in a timely manner. IoT integration in smart metering systems adds a layer of intelligence to the advanced metering infrastructure (AMI), a communication network that supports smart metering and improves its scalability [64,65].

7. Security Issues, Challenges, and Future Research Directions

In the following section, we address the security issues, challenges, and future research directions.

7.1. Security Issues

The acceptance of IoT technology to develop and manage the smart grid is still in the initial stage, and numerous issues related to privacy and security remain unresolved. The management of the huge volume of data generated remains a key problem for privacy in smart grids because of IoT technology adoption, and the technologies required to enable safe data communication are continuously being developed. Figure 10 shows the classifications of security issues, as well as challenges for IoT-enabled smart grid systems.

7.2. Challenges for Adoption of IoT in Smart Grids

Many obstacles may be raised during the deployment of the IoT. One of the most visible and significant barriers is the huge amount of data that must be handled. Essential technologies that allow the secure communication of data are currently being developed. However, the use of IoT technology for implementing the smart grid is in its beginning stages, and several issues related to privacy and security remain unresolved. In this paper, we discuss three types of privacy and security concerns: the customer domain, the information and communication domain, and the grid domain.

7.2.1. Challenges in the Customer Domain

Many smart devices are connected with each other on the customer side and interact with smart meters. Due to this, users’ privacy concerns arise. The smart meter has all information related to the user, i.e., when the user is available at home or not, the user’s daily activity, watching TV, sleeping time, and the type of appliance the user uses. If the smart meter compromises the users’ privacy, it is very dangerous. A vast amount of data are created on the customer side, so preventing that information from malicious intruders is a big challenge. While some solutions have been developed to solve the security issues in the smart grid, vulnerabilities still exist [66].

7.2.2. Challenges in the Information and Communication Domain

Information and communication domains play a crucial role in the transmission of data and participation of IoT-enabled devices in IoT-aided smart grids. They can be categorized as short- and large-range communication networks, such as the IP-based Internet, PLC, 2G/3G/4G mobile networks, and satellite networks facilitate network connectivity in large areas, whereas Bluetooth, ZigBee, and Ultra-Wideband are used for information transmission in limited-range communication networks [67]. This part deals with the transmission of data, so the chances of IP-based network attacks arise, i.e., IP spoofing, TearDrop, Eavesdropping, or DDoS, and these attacks will disrupt the whole grid operations. We can prevent the system by properly implementing intrusion detection systems and firewalls. Confidentiality, authenticity, and integrity are also challenging tasks. We must use advanced encryption and authentication technologies to address these problems [68]. The legacy issue for IoT integration with smart grid is also a real challenge because in most cases there is no way to substitute for them with new systems or update them to support the desired security solutions.

7.2.3. Challenges in the Grid Domain

The main challenge in grid deployment is efficient interoperability between different communications networks. Since the smart grid is deployed with a large collection of devices, a security challenge arises. Such devices are a potential target for hackers [69]. SCADA systems are being used for monitoring and managing the grid region, and there may exist some network configuration and hardware limitations at the SCADA network level. There are many security challenges in SCADA, i.e., challenges in public data availability, policy, and strategy; challenges in platform configuration, denial of service, network configuration, network perimeter, and network communication. These problems must be appropriately addressed. Apart from this, smart meters also have some security challenges. They can also experience physical attacks, such as the removal or alteration of battery, so unauthorized changes may also occur [68,70].

7.3. Future Research Direction

In recent decades, there has been significant growth in smart grid R&D. That is why smart grid technology has moved from the virtual domain to the concept of execution. In the last few years, there has been a massive increase in smart grid research, and it will soon be a huge success in different aspects of the electrical power system, such as power distribution, providing more flexibility and efficiency. Much research work is being performed to develop smart grids. Future research on many components in various areas of the smart grids still has a lot of scopes, such as forecasting, power flow optimization, connectivity, microgrid integration, consumption and energy management systems, interoperability, scalability, economic aspects, cyber security, and most importantly, the automation of generation, transmission, and distribution are all included.

Because the smart grid incorporates various gateways and IoT-enabled devices with varying standards and different resources, interoperability is essential for information transmission. The adoption of IP-based networks is one way to accomplish interoperability. Another option is for the IoT devices to be able to communicate via various protocols and architectures. Smart meters, sensors, and other smart systems that assess and gather data in a smart grid generate large amounts of data, which can waste amount of energy and other resources and cause a bottleneck. The smart grid must be based on the idea that it can efficiently retain and handle this massive volume of data. Although there are numerous IoT standards, there is no uniform standard for the IoT devices used in smart grid systems. This could compromise the security, reliability, and interoperability of IoT devices in the smart grid. Hence, standardization must be consolidated.

Furthermore, in order to monitor and control the IoT devices involved in the smart grid, we must rely on the Internet, which is extremely vulnerable. Attackers can modify data collected by sensors and smart meters, resulting in significant losses. As a result, researchers should provide communication safely for IoT devices in the smart grid while considering their resource constraints and determining specific security precautions for these devices.

The IoT will enhance existing smart grids by enabling real-time control and monitoring of grid components. However, cybersecurity concerns have been seen as one of the biggest barriers to the widespread adoption and expansion of IoT in smart grid systems in the last few years. Due to the large number of devices connected to communication networks, grid-connected devices are more vulnerable to cyberattacks and severe consequences. It is projected that by 2025, 30.9 billion IoT devices will be deployed globally, with 19% placed in the energy sector. This shifts the emphasis of cyberattacks to the energy sector by 54 percent [71]. Security should be addressed across the IoT-enabled SG system, from the IoT gateway through the monitoring stations. In order to do this, security measures can be divided into those needed for data protection, endpoints, and communications, those needed for secure monitoring and analysis processes, and those needed to protect configuration and management operations. Endpoints in the IoT-enabled smart grid must communicate with one another, and this communication is where the vulnerability lies. To resolve this, an authentic identity can be deployed to authenticate and authorize the endpoints for the communications. Furthermore, numerous cryptography tools and methods can be used for secure communication. These security challenges can be overcome with the help of cutting-edge technologies such as blockchain technology, machine learning, and artificial intelligence. These technologies can also be used to make the smart grid system run more securely and efficiently [72,73].

8. Conclusions

The IoT-enabled smart grid is an upcoming grid system that has the potential to solve various challenges and issues of the traditional grid. The main objective of IoT is to enable ubiquitous and seamless connectivity to a vast range of devices located all around the globe. Integrating IoT devices with equipment such as sensors, cameras, and smart meters across the grid can significantly improve data acquisition and analysis, thereby taking the monitoring system and asset management of the smart grid to the next level. The integration of the IoT with a traditional power grid system turns it into a smart one by enabling it to take smart decisions during different phases of energy flow namely, its generation, transmission, distribution, and finally consumption. This work presents a comprehensive study of IoT-enabled smart grid systems comprising features, architectures, prototypes, applications, advantages, and challenges arising in the integration of the IoT and smart grid technology. The concept of IoT-enabled smart grid is developed by using an all-encompassing layered approach. Different technologies and their advantages in the smart grid are evaluated using this framework and its layers. Some of the latest research attempts at each tier of the IoT-enabled smart grid model are evaluated in order to categorize innovative solutions for integrating IoT technologies in the smart grid. The study concludes by highlighting some of the future research perspectives along with the most critical measures required to implement the IoT-enabled smart grid. Some of the key issues affecting the performance of IoT-enabled smart grid systems, such as the interoperability and integration of devices, data management, and grid security, are also identified during this study. Despite the fact that IoT-enabled smart grid systems would outperform the existing power grid systems, the issues identified during the study and mentioned above are posing some serious challenges before the research community and require serious attention.