Smart grids are emerging as an effective and flexible solution to respond to changing patterns of power demand and usage, by using digital communications technology. Smart grid refers to a combination of power systems and communication, information and control infrastructures, which are able to monitor, manage and optimise the operations of all parts of the power system. It aims to improve the economic performance, efficiency, flexibility, reliability, resiliency, safety and security of a power system that includes generation, transmission, distribution and consumption in the presence of renewable and distributed energy resources (DERs), plug-in hybrid electric vehicles (PHEVs), plug-in electric vehicles (PEVs), demand-side management (DSM) and demand response (DR).
In order to achieve these targets, an advanced information and control infrastructure, equipped with an appropriate two-way communication system that is able to exchange and deliver real-time information and electricity to the different components of the smart grid is required. Intelligent electronic devices (IEDs), including sensors, smart meters, protective relays, circuit breakers, reclosers and phase measuring units (PMUs) are the key components of a smart grid that require communication infrastructures to efficiently exchange information and control instructions in an automated way.
To this end, the Internet of Things (IoT), which is an Internet network based on a protocol of exchanging information and communication among various smart devices in order to achieve monitoring, tracking, management and location identification objectives, can facilitate smart grid functionality at the generation, transmission, distribution and customer levels. In the current scenario of the rising load of electronic devices and emergence of new sources of generation and high electricity consumption sources like smart appliances, smart homes, electric vehicles (EVs) etc., the dependence of smart grids on IoT-based solutions is increasing. This has opened the door to innovations for establishing an effective communication network for smart grids.
Communication network of a smart grid
Communication networks for a smart grid can be presented as a hierarchical multilayer architecture, which include wide area network (WAN), neighbourhood area network (NAN) and home area network (HAN). HAN is the first layer; it manages the consumers’ on-demand power requirements and consists of smart devices, home appliances (including washing machines, televisions, air conditioners, refrigerators and ovens), EVs as well as renewable energy sources (such as solar panels). HAN is deployed within residential units, in industrial plants and in commercial buildings and connects electrical appliances with smart meters.
NAN, also known as field area network (FAN), is the second layer of a smart grid and consists of smart meters belonging to multiple HANs. NAN supports communication between distribution substations and field electrical devices for power distribution systems. It collects the service and metering information from multiple HANs and transmits it to the data collectors that connect NANs to a WAN.
WAN is the third layer of a smart grid and it serves as a backbone for communication between network gateways or aggregation points. It facilitates the communication among power transmission systems, bulk generation systems, renewable energy sources and control centres. Additionally, video cameras have been used in smart grid management to build video surveillance systems for asset safety, fire alarm and safe operations. Integrated supervisory control and data acquisition (SCADA) systems have been used with video cameras embedded in the supervisory graph to improve efficiency.
Figure 1: Smart grid architecture presenting power systems, power flow and information flow
Source: IEEE
Integration of IoT into smart grids
The driving force behind smart grid implementation is to improve power system planning, maintenance and operations by ensuring that each component of the grid is able to ‘listen’ and ‘talk’ and be automation-enabled. Here, IoT plays the key role by providing IP addresses to the components, making them capable of two-way communication. IoT can be applied to all smart grid subsystems – power generation, power transmission, power distribution and power utilisation – and appears to be a promising solution for enhancing them, making the IoT a key element for a smart grid.
Figure 2: Existing and potential applications of IoT-aided smart grid systems
Source: IEEE
Existing applications of IoT-aided smart grid systems
WAN applications
1) Transmission tower protection: With the help of wireless sensor networks (WSNs), IoT technology is capable of facilitating remote monitoring to address security threats to transmission towers. The IoT-aided transmission tower protection system contains various sensors, which generate early warnings of threats to high voltage transmission towers, enabling quick responses. The sensors include vibration sensors, anti-theft bolts, a leaning sensor and a video camera. These sensors, along with a sink node, form a WSN. The sensors detect any threat and send the relevant signals to the sink node. The sink node receives these signals from the sensors, processes them into data and transmits the data to the monitoring centre through the Internet or any other public/private communication network. The monitoring centre handles the real-time data of a series of transmission towers. The alarm signal and images from the sink node inform the monitoring centre staff about any threat to a transmission tower and the staff then takes appropriate actions to handle such threats.
2) Online monitoring of power transmission lines: This is one of the most important applications of the IoT in the smart grid, specifically for disaster prevention and mitigation. Sensors measuring conductor galloping, wind vibration, conductor temperature, micro-meterology and icing can now be used to achieve real-time online monitoring of power transmission lines. IoT enables the communication between power transmission line sensors and transmission tower sensors.
NAN applications
1) Smart distribution: Smart grids at the power distribution level are characterised by high reliability, improved power quality, better compatibility with the changing demand patterns of the consumers, better communication systems, higher utilisation rate of power grid assets, and are equipped with a visualisation management platform. Smart distribution based on advanced automated IoT technology can immediately identify faults and instantly overcome them.
2) Smart patrol: Smart patrol comprises WSN and radio-frequency identification (RFID) tags, which are connected to a power substation with the help of IoT technology and are used to trace the location of power equipment to improve patrolling, as well as to enhance the stability, efficiency and reliability of a power system and its supply. Smart patrol can be used for several applications, such as patrol staff positioning, equipment status reports, environment monitoring, state maintenance and standard operations guidance.
HAN application
1) Smart homes: IoT is applied to various aspects of smart homes. For instance, in a LAN protocol, sensors can be used for controlling smart appliances, multi-meter reading, information gathering of power consumption (including electricity, water and gas), load monitoring and control, and user interaction with smart appliances. IoT technology also provides its services to NANs, linking a group of smart homes in a neighbourhood through a NAN to form a smart community. The concept of the smart community could be extended to form a smart city.
2) Information management system for EVs: The charging system for EVs comprises a power supply system, charging equipment and a monitoring system. IoT technology plays a leading role in the monitoring system by providing an information management system that integrates different components of the charging station. EVs are equipped with global positioning systems (GPS), which let the IoT help drivers manage their batteries more efficiently by locating the nearest, most suitable charging station with the shortest waiting time, as well as providing traffic and parking information.
3) Advanced metering infrastructure (AMI): An AMI system is one of the most important components of a smart grid. It collects and processes the real-time electricity consumption data with high reliability, and hence provides real-time monitoring, statistics and power consumption analysis. IoT enables AMI or remote meter-reading systems based on WSN and PLC and optical PLC (OPLC) by using public or private communication networks. Thus, IoT technologies help consumers save money by adjusting their electricity usage behaviour based on an analysis of their power consumption.
4) Integration of DERs: Power generation patterns of renewable energy sources (solar and wind) that are distributed across the grid, intermittent in nature and dependent on location and climate pose significant challenges for predictability and reliability of power supply. Such problems are addressed using the seamless interoperability and connectivity provided by IoT technology. Furthermore, IoT technology uses sensors to collect real-time weather information, which helps in accurately forecasting energy availability in the near future.
5) Power demand management: It is used to minimise a consumer’s electricity bill, lower operational costs of the power grid, reduce energy losses, as well as to shift the demand load from peak times. IoT devices collect the energy consumption requirements of various home appliances and transmit them to the home control units.
Although various applications of IoT-aided smart grid systems are available, their usage remains limited. Some applications of IoT-aided smart grid systems have already been deployed, but many more are yet to materialise.
Big data analytics and cloud for IoT-aided smart grid systems
Need for big data
The integration of IoT technology with the smart grid comes with a cost of managing huge volumes of data, with frequent processing and storage. Such data includes consumers’ load demand, energy consumption, network components’ status, power line faults, advanced metering records, outage management records and forecast conditions. This means that the utility should have the hardware and software capabilities to efficiently and effectively store, manage and process the data collected from IoT devices.
Big data is defined as data with huge volume, variety and velocity (three Vs). The high frequency of data collection by IoT devices in a smart grid makes the data size very large. The variety is represented by the different sensors that produce different data. Data velocity is the required speed for data collection and processing. Hence, IoT-aided smart grid systems can apply the techniques of big data management and processing (such as hardware, software and algorithms).
Cloud computing
Cloud computing techniques can be used to keep devices like SCADA up to date. The SCADA system is the main element of decision-making in a smart grid. It collects data from IoT devices that are distributed across the grid and provides real-time online monitoring and controlling. Additionally, it helps manage the power flow throughout the network to achieve consumption efficiency and power supply reliability. Generally, it is located on local computers at various sites of the utility companies. With the growing size of smart grids, utilities face the challenge of keeping SCADA systems updated and upgraded. To solve this problem, cloud computing is a good solution to host SCADA systems. Cloud computing enables on-demand access to a shared pool of computing resources, such as storage, computation, network, applications, servers and services.
Fog computing
Sending and storing data on the cloud raises security risk issues, due to the shared storage among several users, which makes it vulnerable to attacks. Fog computing is used to solve this security risk. Fog computing does not require data transfer to the cloud and the data is processed by devices that are located at the network edge.
IoT and non-IoT communication technologies for smart grids
Communication systems for smart grids can be categorised as wireline and wireless technologies, including the conventional communication technologies that can potentially be employed in smart grids. A smart grid requires two types of information flows – firstly, among smart meters and IoT devices, sensors and home appliances; and secondly, between smart meters and utility control centres. The first data flow can be achieved through powerline communications or wireless communications, such as by using 6LowPAN, ZigBee and Z-wave. The second data flow can be achieved by using cellular communications or via the Internet. However, there are various limiting factors that should be considered when deploying smart metering, such as operational costs, deployment time, availability of technology and the operating environment (such as rural, urban, indoor, outdoor). Hence, technology that suits one environment may not be applicable in another.
Some of the critical communication network/system characteristics that should be considered before making a choice are:
- Bandwidth: the frequency range used for data transfer
- Coverage area: the physical area and the distance where the communication is available
- Data rate: the speed of data transfer from the source to the destination or the amount of data transferred within a certain time duration
- Latency: the time required to exchange data from the source to the destination
- Reliability: the criterion indicating the availability of a data transfer system and its ability to exchange data
- Security: the ability of the communication infrastructure to encounter physical and cyber security attacks to provide an acceptable data transfer condition
Based on the purpose and application of communication systems in a smart grid, the communication infrastructure needs to meet the required technical conditions. Various IoT and non-IoT communication technologies and their details are available in Table 1.
The way forward
Though IoT-based communication technologies/solutions provide vast scope for digitisation of the gird, they have their limitations, which provide scope for further technological advancements. For instance, though big data and cloud computing provide effective solutions to manage and analyse huge data collected by IoT systems, the presence and exchange of data at multiple levels makes it vulnerable to cyberattacks. Thus, this area provides scope for further research and technological advancement in IoT devices to secure data.
Another way to further advance IoT systems would be to use artificial intelligence (AI) techniques. For instance, machine learning can help IoT-aided smart grid systems learn from past actions and improve decision-making.
IoT devices also use huge amounts of energy to operate, mainly based on batteries. Thus, efficient energy storage sources for IoT and energy generation devices need to be used or designed. Other techniques/technologies that can be used to improve the performance of IoTs are data fusion, which filters and aggregates only useful data from multiple IoT devices to enhance the efficiency of data collection, as well as save energy and bandwidth; and data congestion and delay reduction.
A highly awaited next-generation cellular communications network, 5G (fifth generation), which is the successor of 4G and aims to significantly increase the speed and responsiveness of wireless networks, will play an important role in enhancing the communication network of the grid. 5G enables utility centres to remotely connect to the assets of the whole distribution grid. Hence, 5G is a very suitable technology for the smart grid, mainly for distributed monitoring and control functionality.
The upcoming 5G communication network comprises multiple attributes such as ultra-high capacity, ultra-large bandwidths, ultra-dense sites, and ultra-reliability as well as compatibility with various existing information and communication technologies (ICT) and fog computation. There are several studies on the integration of 5G communications in smart grids. Furthermore, smart grids can take advantage of advanced distributed state estimation approaches granted by 5G for distributed monitoring and control functionalities, and implementation of critical and real-time applications in future grids.
Table 1: IoT and non-IoT communication technologies for smart grids
|
Technology |
Protocol |
Advantages |
Applicability |
Smart grid application areas |
Data rate |
Coverage rate |
|
IoT Wireless Technologies |
5G |
Low latency; high reliability, bandwidth and speed; capable of handling large number of devices |
NAN, WAN |
Distributed monitoring and control |
Up to 20 Gbps |
10-100 metres (m) |
|
Z-Wave |
No interference with other wireless technologies; reliable; low latency; scalable |
HAN |
Home automation |
100 Kbps |
30 m |
|
|
6LoWPAN |
Robust; low power, support large mesh network topology, applicable on various communication platforms |
HAN |
Smart metering; home automation |
250 Kbps |
10-100 m |
|
|
LoRaWAN |
Low power; low range; no interference with different data rates; create virtual channels; low cost; secure |
NAN, WAN |
Management of operation and equipment; online monitoring of power transmission lines and towers |
0.3-50 Kbps |
2-5 km (urban areas); 15 km (suburban areas) |
|
|
ZigBee |
16 channels each with 5 MHz of bandwidth in 2.4 GHz spectrum; low power usage; low complexity; low deployment cost |
HAN |
Energy monitoring; smart lightning; home automation; automatic meter reading |
250 Kbps |
10-100 m |
|
|
Wireless HART |
Backward compatibility; reliability; robustness |
HAN, WAN |
Smart meters; power generation |
115 Kbps |
200 m |
|
|
Bluetooth |
Low power consumption |
HAN |
Home automation |
721 Kbps |
1-100 m |
|
|
Bluetooth low energy |
Ultra-low power consumption; low cost; low complexity |
HAN |
Home automation |
25 Mbps |
5-10 m |
|
|
Narrowband IoT |
Crowd-free unlicensed bands; ultra-low power consumption; low cost; low complexity |
HAN, NAN |
Home automation; AMI |
230-250 Kbps |
35 km |
|
|
Non-IoT Wireless Technologies |
Cellular communication |
Wide area coverage; improved QoS |
HAN, NAN, WAN |
Monitoring and management of DERs; SCADA |
60-240 Kbps |
10-50 km |
|
Wireless Mesh |
Low cost; self-healing; self-organisation; high scalability; high data rate |
HAN, WAN |
Monitoring and controlling of DERs; automation and protection of substations |
Depends upon protocol |
Depends upon deployment |
|
|
WiMAX |
Long range; high data rate |
HAN |
Real-time pricing; automatic meter reading; outage detection and restoration |
75 Mbps |
10-50 km (LOS); 1-5 km (NLOS) |
|
|
Mobile broadband wireless access |
Low latency; high mobility; high bandwidth |
NAN, WAN |
Broadband communication for EVs; SCADA system; wireless backhaul of smart grid monitoring |
20 Mbps |
Vehicular standard (up to 240 km/h) |
|
|
Digital microwave |
Long distance coverage; high data rate; high bandwidth |
HAN, NAN |
Transfer trip between DER and distribution substation |
155 Mbps |
60 km |
|
|
Non-IoT Wired Technologies |
Powerline communication |
Cost effective; low installation cost; wide availability; utility’s own ownership and control; dedicated network |
HAN, WAN |
Low voltage distribution; automatic meter reading |
2-3 Mbps |
1-3 km |
|
Digital subscriber lines (DSL) |
High speed; low latency; low installation cost; high data rate; high capacity; long range; wide availability |
HAN, WAN, NAN |
Smart metering |
1-100 Mbps |
5-28 km |
|
|
Optical communication |
Long distance communication; ultra-high bandwidth; robustness; high reliability |
WAN, NAN |
Physical network infrastructure |
Up to 100 Tbps |
10-60 km |
Note: Majority of the technologies are based on HAN, however, there is a new IoT communication technology, LoRaWAN, which is a very good candidate for NAN and WAN, and it is a long-range and low-power communication technology.
Source: IEEE
