**3. IoT-Based Hybrid AC/DC RES Environment**

Communication networks are critical components of HRES because they allow data to flow between data sources (sensors and meters), control centers, and controllers. The data flow from various elements establishes the system architecture in addition to facilitating the control operation and remote monitoring [143]. Sensing, communication, processing, and actuation will all benefit from IoT technology, which will facilitate a variety of MG applications. This research concentrates on the amount of communication between the HRES local controller and the MG control center, in which the condition of various RESs and loads can be gathered and reported to a central controller, which decides the required system action.

#### *3.1. Real World Applications of IoT*

From agriculture to health care, IoT services and intelligence can alter the lives of ordinary people. As this innovation [144] advances at a breakneck pace, it will logically anticipate population requirements and benefit society as a whole. The real-world implementations of IoT are depicted in Figure 6, which range from the retail industry to health services. In terms of IoT, the most popular phrase is "smart home." It has emerged as a progressive component in the residential sector, and smart homes are expected to be as common as smartphones in the future. Smart home devices [145] will gain branded household products as energy, and automation progresses, reducing consumers' time and, ultimately, money. This is a critical aspect for certain smart items to communicate digitally in order to provide users with a cost-effective experience. IoT devices are always being improved to make them more compact and energy efficient.

improved to make them more compact and energy efficient.

**Figure 6.** IoT in the real world. **Figure 6.** IoT in the real world.

required system action.

the future.

cities and industrial IoT.

*3.1. Real World Applications of IoT*

As per a Forbes survey [146], leading brand businesses are expected to sell over 411 million wearables on the digital market by 2020. In article [147], the future necessity for addressing those uncertainties is explored using an IoT-based architecture. With the advancement of IoT technology, the theory of smart cities is gaining popularity. The requirement to analyze necessary protocols for urban IoT platforms [148,149] with optimized speed routing algorithms in smart streets for specific situations must be prepared for in the future.

the HRES local controller and the MG control center, in which the condition of various RESs and loads can be gathered and reported to a central controller, which decides the

From agriculture to health care, IoT services and intelligence can alter the lives of ordinary people. As this innovation [144] advances at a breakneck pace, it will logically anticipate population requirements and benefit society as a whole. The real-world implementations of IoT are depicted in Figure 6, which range from the retail industry to health services. In terms of IoT, the most popular phrase is "smart home." It has emerged as a progressive component in the residential sector, and smart homes are expected to be as common as smartphones in the future. Smart home devices [145] will gain branded household products as energy, and automation progresses, reducing consumers' time and, ultimately, money. This is a critical aspect for certain smart items to communicate digitally in order to provide users with a cost-effective experience. IoT devices are always being

As per a Forbes survey [146], leading brand businesses are expected to sell over 411 million wearables on the digital market by 2020. In article [147], the future necessity for addressing those uncertainties is explored using an IoT-based architecture. With the advancement of IoT technology, the theory of smart cities is gaining popularity. The requirement to analyze necessary protocols for urban IoT platforms [148,149] with optimized speed routing algorithms in smart streets for specific situations must be prepared for in

In the automotive digital industry, IoT provides the way for vehicles that are more stable and robust in terms of performance. Connected automobiles with IoT capabilities use pre-stored inputs based on several sensors to regulate the vehicle's functioning more independently. IoT-enabled automotive revolution brought together larger branded firms from both the IT and automotive industries. The industrial sector is the next most important market for economic growth. With the growth of analytics, big data [150], progressive software resources, and enhanced sensors, Industrial IoT has the potential to empower whole sectors. Figure 7 shows that the majority of the market is focused on smart

In the automotive digital industry, IoT provides the way for vehicles that are more stable and robust in terms of performance. Connected automobiles with IoT capabilities use pre-stored inputs based on several sensors to regulate the vehicle's functioning more independently. IoT-enabled automotive revolution brought together larger branded firms from both the IT and automotive industries. The industrial sector is the next most important market for economic growth. With the growth of analytics, big data [150], progressive software resources, and enhanced sensors, Industrial IoT has the potential to empower whole sectors. Figure 7 shows that the majority of the market is focused on smart cities and industrial IoT. *Energies* **2022**, *15*, 6813 15 of 28

By actively communicating with industrial data, the IoT helps create a more trust-

Another important sector where IoT solutions are becoming more prevalent is healthcare, which aims to provide high-quality and timely services to patients. Patients and doctors can engage with each other on a routine basis because of the IoT. The global market can be expanded as a result of the use of various IoT-based smart devices that have high consumer satisfaction. With this technology, the requirements for luxury, security, safety, and cost-effectiveness can be met. Table 8 depicts the fundamental characteristics

> The data stored are immediately available because many equipment and services are dynamically connected to one another. The data are susceptible to hackers and

Currently, few worldwide compatibility standards; it is difficult for suppliers and consumers to interface with services.

**Remedy**

Concentrating on more data verification tools can help solve this

Similar protocols for multiple sectors, such as commercial, industrial, and residential, might be used to generate new standards.



problem.

identify issues earlier, resulting in higher profits and productivity. In the near future, industrial IoT will focus on sensor cloud-based integrity communication [152]. New agricultural innovation is desperately required to meet the increasing demand for food supply. Only by combining innovative agronomics techniques with end-to-end IoT technologies can this be possible. Crop monitoring is performed effectively, and the persistence of a range of crops may be done in a very fair manner, resulting in more efficient water man-

**Figure 7.** General market structure of IoT technologies [151]. **Figure 7.** General market structure of IoT technologies [151].

of IoT, as well as its benefits and drawbacks.

**Table 8.** Benefits and drawbacks of IoT.

agement.

Automation The key benefit is that it can keep the entire

ers to focus on other tasks.

quality and time factors.

Security and Privacy. -

Compatibility -

The system's performance is enhanced, and the presence of a M2M interface allows work-

By talking with devices [3 N] on a daily basis, IoT develops a platform that enhances the

Efficacy

Communication

**Features Pros of IoT Cons of IoT Possible Concerns towards the** 

M2M communication process transparent. - -

unauthorized concerns.

By actively communicating with industrial data, the IoT helps create a more trustworthy solution. As a result, industries may more efficiently address inefficiencies and identify issues earlier, resulting in higher profits and productivity. In the near future, industrial IoT will focus on sensor cloud-based integrity communication [152]. New agricultural innovation is desperately required to meet the increasing demand for food supply. Only by combining innovative agronomics techniques with end-to-end IoT technologies can this be possible. Crop monitoring is performed effectively, and the persistence of a range of crops may be done in a very fair manner, resulting in more efficient water management.

Another important sector where IoT solutions are becoming more prevalent is healthcare, which aims to provide high-quality and timely services to patients. Patients and doctors can engage with each other on a routine basis because of the IoT. The global market can be expanded as a result of the use of various IoT-based smart devices that have high consumer satisfaction. With this technology, the requirements for luxury, security, safety, and cost-effectiveness can be met. Table 8 depicts the fundamental characteristics of IoT, as well as its benefits and drawbacks.


**Table 8.** Benefits and drawbacks of IoT.


**Table 8.** *Cont*.

#### *3.2. IoT Technologies for MG*

In today's world, several IoT-based solutions are accessible to meet the demands of MG applications. Despite the fact that numerous communication technologies are suitable, there are currently few standards for the effective implementation of MG. IoT technologies are mostly employed in MG for long-range bi-directional data exchange among the utility and the user via IoT-based equipment, such as smart meters. In most cases, IoT-based MG systems require advanced wireless technologies rather than wired-based technologies to alleviate the difficulty of long-distance data transfer. Certain wired methods [153], are necessary for the event of signal attenuation-related interference because these technologies will not depend on batteries to operate.

Wireless methods can be used to transfer data between smart meters and IoT-enabled devices, as shown in Table 9. Various wireless communication technologies based on IoT are detailed in this table, along with their coverage ranges, which can be utilized for MG systems. IoT can facilitate the flow of data between utility data centers and different smart meters. Different wireless techniques are required to obtain these systems together, which presents a difficult microcosm for IoT-based MG systems. Long-range connectivity is demonstrated by cellular-based networks such as LoRa [154] and Sigfox [155], which are used to build the backbone network for future grids with cloud-based service domains. MG systems will primarily focus on exhibiting long-range connectivity [156,157] and establishing a network structure with cloud-based application areas.

**Table 9.** Wireless technology based on the IoTs with an MG coverage range.



**Table 9.** *Cont*.

The majority of MG systems center on NAN and WAN [155], which need maximum range and minimum power technologies. For such technologies, LoRaWAN [158] emerges as a potential player. Aside from these wireless technologies, it is important to remember that determining the optimum technology for MG is impossible because most of these wireless technologies are possible candidates for MG-based applications. Several wired technologies, such as DSL [159] and power line communications [160–164], are widely employed in rural settings, and are paving the way for smarter technology. Table 10 depicts IoT device which is connected worldwide.

**Table 10.** IoT devices connected worldwide.


#### *3.3. IoT in Energy Management Optimization*

MGs are becoming more popular as a result of renewable energy projects around the world. They have a lot of benefits, but they also have a lot of drawbacks, especially when it comes to working with traditional MG's. SEMS are developed to assist grid operators in managing energy production and consumption as efficiently as possible in order to save money, minimize CO<sup>2</sup> emissions, and ensure that electrical networks remain stable at all times. In the last few years, the IoT industry has developed quickly, with the advent of very effective open source IoT platforms that are especially well adapted to the development of SEMS. The most significant benefit of the open source IoT strategy is its vendor independence and ability to adapt to changing market conditions [165]. This gives grid operators more control over their assets, allows them to stay current with market demands, and allows them to improve or expand their EMSs to meet their needs. Figure 8 shows the IoT-based optimal EMS for MG.

#### 3.3.1. IoT and Wind Energy Optimization

In terms of efficiency and size, wind technologies are quickly evolving. The primary stumbling block to the growth of wind energy is the intrinsic intermittency of these resources. As a result, if wind units have a high infiltration in fulfilling demand, extreme inequalities could jeopardize the system's security. Furthermore, IoT technology combined with ICT infrastructures enables wind farm owners to plan precise predictive maintenance plans, avoiding costly downtime. On-time maintenance, for example, can lower the LCOE index for wind assets [166], which represents the net present value of the unit–cost of power throughout the turbine's lifespan.

Z-wave

IPv6 over low-power wireless personal area networks (6LoWPAN)

Thread

sigFox

 Provides virtual channels for the improvement of IoT gateways.

Less interference with other wireless

Connectivity easier with large wire-

Low levels of data transfer speed.

Start range.

Short range.

Less suitable for NAN.

Less data rate transfer.

No drawbacks in terms of

**Connected Devices Year** 0.2 million 1999 80 million 2010 9.0 billion 2013 1.0 trillion 2025

data transfer.

MGs are becoming more popular as a result of renewable energy projects around the world. They have a lot of benefits, but they also have a lot of drawbacks, especially when it comes to working with traditional MG's. SEMS are developed to assist grid operators in managing energy production and consumption as efficiently as possible in order to save money, minimize CO2 emissions, and ensure that electrical networks remain stable at all times. In the last few years, the IoT industry has developed quickly, with the advent of very effective open source IoT platforms that are especially well adapted to the development of SEMS. The most significant benefit of the open source IoT strategy is its vendor independence and ability to adapt to changing market conditions [165]. This gives grid operators more control over their assets, allows them to stay current with market de-

Less data rate transfer. Smart meter

Latency found to be low.

 Robust technology. Less power needed.

less platforms.

 Less power needed. More connectivity.

**Table 10.** IoT devices connected worldwide.

*3.3. IoT in Energy Management Optimization*

shows the IoT-based optimal EMS for MG.

 Low power. More secure. Connectivity easier.

devices.

Coverage range—to 15

 Smart home automation. Coverage range—30 m.

Coverage range—to 100 m

 Smart home automation. Coverage range—10 to 30

km.

km.

Smart meter.

**Figure 8.** IoT-based optimal energy management and control for **Figure 8.** IoT-based optimal energy management and control for a MG. a MG.

The need for IoT in the wind energy industry stems from the fact that data related to WTs and wind farms must be obtained and evaluated quickly. Offshore wind farm data transmission delays and limited bandwidth for relaying information to remote areas were two major concerns that can be addressed right now. As a result, decision-making processes can be sped up or automated if important information can be gathered and processed in real time. The use of IoT technologies in the wind industry emphasizes the necessity for better comprehensive strategies for designing and operating wind farms and also installing and maintaining turbines that are cost-effective, secure, and safe. There are a lot of sensors and actuators in the WT controller layer. Each fundamental component's health and function can be reported by the sensors. Using a series of actuators, the control system regulates and configures the components.

The controller accepts sensor information and utilizes power amplifiers to convey electric, hydraulic, and mechanical signals and instructions. Cyber-physical devices must be combined to link the physical layer of wind turbines to the cyber layer via a network architecture. The network, condition-monitoring system, and SCADA make up the cyber layer. The design of a communication network, particularly for offshore wind farms, is largely dependent on local conditions. To connect to a LAN, each turbine must be fitted with an RTU. Such devices share data with a central data center that uses a cloud-based WAN.

All WTs in a wind farm are furnished with IoT-based-distributed intelligence systems and embedded systems that benefit from WSN, as well as M2M communication under cloud-based systems that transmit information to servers using internet-enabled and open communication protocols, and can be controlled and regulated using mobile HMIs or unified computer-aided interfaces. The IoT-based controlling system is said to be more expensive than current SCADA platforms, but due to the higher sampling rate and data frequency, it is said to be more effective at diagnosing. The IEC61400-25 standard, which improves the standardization of the data exchange gateway, diagnostics, autonomy, and extensibility was designed in order to execute unified monitoring and information exchange.

#### 3.3.2. IoT and Solar Energy Optimization

Solar energy offers the greatest potential for renewable energy power generation. As a result, this source is expected to be a significant provider of future clean power systems. Solar panels, switches, wiring, mounting systems, and inverters make up a PV

system. A battery storage unit can be added to these items. Modern techniques, such as the MPPT controlling scheme, global positioning system (GPS) solar tracker, anemometer, solar irradiance sensors, and similar task-specific accessories, are available in modern PV systems for more efficient solar power extraction. Unlike traditional PV systems, CPVs have curved mirrors and optical lenses that assist irradiance onto a small but highly effective multi-junction solar cell. Because solar energy must be stored whenever it is available and the stored energy must be delivered once it is required, the installation of a storage unit is required. IoT can aid in the real-time sharing of data collected from PV sensors, as well as remote controllability of solar unit operation for failure and fault diagnosis, as well as prediction and preventative maintenance. Furthermore, grid-scale synchronization of unpredictable ESS and solar production necessitates real-time communication, which IoT infrastructure may provide. Uncertainties are largely linked to the appraisal of solar resources and the functioning of PV systems.

Monitoring the operation of the arrays is critical because it affects the PV unit's profitability as well as its dependability. In terms of income and O&M performance, identifying and responding to losses caused by a variety of factors is crucial. The performance of arrays can be measured via contracts between the PV system manufacturer, the PV owner, and the utility that guarantee the purchase of the energy produced. The intensity of solar radiation varies with time and is heavily influenced by the weather. As a result, there is no way to generate at a consistent rate. Several system components, such as the battery SOC and the voltage levels of the power converter, are affected indirectly by this issue. It is difficult for people to monitor every PV panel to prevent losses and outages, whether it is a rooftop PV system or a solar park in the desert. Additionally, frequent site visits and monitoring of operating data are necessary, which takes time when the PV facility is situated in a remote area. Human failures take a long time to address, and they are not always obvious. As a result, continuous monitoring of a real-time system that monitors parameters of the PV system and stores relevant information in a cloud-based network is necessary to be installed alongside the PV panels. The information can be utilized to gain a better understanding of the performances of PV systems and the causes of their failure. As a result, the deployment of IoT technology enables diagnosis and on-time maintenance.

#### 3.3.3. IoT and Energy Storage Facilities

By redressing imbalances, ESS assists in boosting the dispatch capabilities of uncertain RESs. Incorporating IoT and processing a massive amount of data, on the other hand, adds a lot of complexity to the equation, but it improves autonomy. One must always strike a healthy balance between intricacy and performance (usefulness). Bulk energy time-shifting, small-scale frequency management, large-scale frequency stability, and power dependability are some of the applications of energy storage devices. Diverse energy storage systems have been developed so far for various uses. Energy storage units are critical for increasing the flexibility of power networks while also ensuring their reliability. The insecurity and intermittent nature of RESs is the key impediment to increased adoption. The use of energy storage facilities can help to decrease the danger of these uncertainties. As a result, real-time integration between these units is essential to avoid undesirable restrictions due to excess generation or detriments as a result of inadequacies. IoT infrastructure can help to make this a reality by allowing wind farms or solar parks to work together with grid-scale energy storage facilities, increasing the profitability of both types of facilities.

#### 3.3.4. Drawbacks of IoT in Microgrid

Specific technological difficulties would need to be overcome in order to support the rapid technical development of IoT technologies as well as innovative potential application areas [167]. One of the main issues is associated with the development of different tools for the monitoring of network operations [168], then issues with security tools and their management [169], issues with software bugs, demanding maintenance of IoT networks, and finally, security issues related to IoT networks [170]. The key issue with the effective

adoption of IoT technologies is related to the speed and coverage of wireless networks (Wi-Fi), where expectations are high due to both noticeable gains in Wi-Fi network coverage and increases in Wi-Fi speed over the period of 2017–2022. Globally, rises in Wi-Fi speed of more than a factor of two, or from around 24 Mbps to more than 54 Mbps, are anticipated. The Asian region is predicted to experience the greatest improvement in Wi-Fi speed [171].

#### **4. Open Issues and Future Research Directions**

IoT-based MG systems operate in a variety of situations, such as transmission line monitoring; thus, it is critical to consider aspects, such as dependability, accessibility, and compatibility with various communication technologies [172–174]. In the future, selfhealing measures should be explored in conjunction with IoT technologies. If, for example, a large number of IoT devices break down, a remedial method based on self-healing capacity must be chosen, and the validity of IoT-based systems must be governed by the manufacturer. Energy acquisition, security challenges, and creating standards are also key considerations for IoT-based MG systems. Real-time power line monitoring necessitates a variety of sensors and nodes for delivering data, which is often powered by batteries. For IoT-based MG systems, most end devices are powered by batteries. As a result, obtaining power for such IoT-enabled equipment is a major outstanding question to implement such systems in the coming years. As a solution, novel energy harvesting tools in conjunction with IoT equipment must be created.

For implementing the IoT in their applications, different power supply solutions are required. Because not every power supply is suited for it, the task of designing the power supply items must also be economical, efficient, and capable of balancing heavy and light loads. Smart meters, for example, transmit a large quantity of data between the consumers and the utility. Future smart meter data flow will necessitate more sophisticated communication networks such as 5G and 6G to provide adequate wireless connectivity. Knowing the consequences prior to deployment is a critical component of this system, creating an open problem for IoT-based MG. Communication and information networking are crucial for the efficient implementation of IoT-based MG systems. As IoT MG systems evolve on various wireless networks for transferring information ranging from device scheduling to real-time EMS and power delivery, desirable and dependable network performance becomes increasingly crucial.

Expanding to modern wireless communication from 2G to 6G networks is essential for current MG structures, which will pave the way for future interdisciplinary research between electronics and electrical engineers. For such devices, different data fusion solutions are required, as they must combine data from several sources. As a result of the low processing capabilities of several IoT devices in IoT-based MG systems, storage capacity becomes a resource constraint. As a result, all of the gateways are insufficient to handle the data. Data fusion solutions for IoT-based MG systems will be a unique and innovative sector in the future for identifying the essential data from devices. Due to the different research interests on IoT [175] and MG standards, the focus on developing complete principles of IoT-based MG technologies in the future has been eliminated. The need to shift actual concentration criteria for this technology in a complementary manner is a critical open issue in the modern energy market. Data integrity [176] is becoming more important in these systems because it ensures that data collected from devices, such as smart meters, are not tampered with by unauthorized individuals.

#### **5. Conclusions**

The paper provides a brief summary of the various elements that make up a HMGS, including optimization and control topologies, as well as the problems that have to be addressed. The implementation of a decentralized power system and the smart grid paradigm was developed by the HMGS. It has many advantages over standard power networks due to its increased reliability, removal of numerous conversions, and auxiliary service. Similarly, the convergence of IoT is predicted to significantly enhance energy

efficiency, functionality, and cost-effectiveness, paving the way for total automation to an IoT-based MG state. Several regulatory-based organizations and government organizations across the world have increased their focus on MGs in the electricity market in industrial, commercial, and residential buildings as a result of the creation of IoT-based regulatory standards and frameworks. Continuous regulation, including authorization based on carbon emission objectives, is required in all regions of the world, according to this remark. As a result, energy stakeholders should investigate next-generation IoT technologies in order to deal with the complexity of EMSs. As the globe proceeds toward the smart MG revolution, as addressed in this review article, there are many prospects for boosting the economy as MGs based on IoT systems face certain hurdles. Furthermore, the rapid growth of appropriate IoT designs with MGs, as well as standards, are required and will be useful in the technological arena. The operation of a HMGS depends greatly on power management strategies and control techniques, necessitating a thorough analysis of various MGs under various conditions. Additionally, it offers suggestions for future (focused) lines of inquiry in this sector.

**Author Contributions:** Conceptualization, S.V., V.I., B.A. and R.V.; Methodology, S.V., V.I. and B.A.; Software, S.V.; Formal Analysis, S.V., V.I. and B.A.; Investigation, S.V.; Resources, S.V. and B.A.; Data Curation, S.V., V.I. and R.V.; Writing–original draft preparation, S.V. and V.I.; Writing—reviewing and editing, S.V., V.I. and R.V.; Visualization, V.I.; Supervision, B.A. and V.I. All authors provided critical feedback and collaborated in the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of Interest.

#### **Nomenclature**

