Smart cities necessitate modern infrastructure, and a smart grid is at the top of the list of requirements.
A Smart City can be defined as one in which different types of sensors and data acquisition technology supply information that is used to manage assets and resources efficiently — through a network nowadays known as the Internet of Things (IoT). This includes data collected from citizens, devices and assets that is processed and analysed to monitor and manage traffic and transportation systems, power plants, water supply networks, waste management, law enforcement, hospitals, emergency services and other community services. It could be said that most of the objectives of the smart city relate to social improvements, lifestyle change and sustainability.
Underlying it all is energy as an enabler: whether it be supplying essential infrastructure, such as hospitals and transport, or supplying residential communities, businesses and industry. As a result, a smart city needs a ‘Smart Grid’.
The need for a smart grid
Many of the energy requirements of a smart city can be addressed through smart grid technologies.
Reliability seems to be an obvious requirement, but it has several separate elements, namely:
- reliability of supply
- protection against cyber attacks
- incident response.
Even in the best engineered network problems can arise, whether through faults in the system itself or through external events. A well-designed and smart grid needs to use redundancy to protect supply, distributed intelligence to rapidly identify outages and assess impacts, analytics to identify potential problem areas and automation to avoid outages and restore services. We have already had dramatic examples of failures in this area in recent years in Australia.
As the grid becomes smarter and more interconnected digitally, then it also becomes more vulnerable to cyber attack from cybercriminals and hostile agencies and nations, making well-designed security protections essential for reliability.
A smart grid should also supply sufficient detailed information in real time to allow for effective response in the event of an incident affecting reliability, or to predict failures before they occur.
Energy efficiency in relation to the smart grid involves the minimisation of energy losses. In the case of high- and medium-voltage distribution networks, they are well monitored and optimised to reduce losses as far as possible, and normally this would already be in place.
It is the low-voltage network that is less well monitored or even unmonitored, and so is largely not optimised for reducing losses based on actual load. A smart grid system utilising smart metering and other technologies can help to alleviate this issue.
Energy consumption and generation
Maintaining a balance between consumption and generation has always been a challenge, but with the smart city, there is the opportunity to better exploit microgeneration (such as residential solar), local storage and new consumption types such as electric vehicles.
Information, modelling and automation are key to any sophisticated demand-response management system. Having accurate information about energy flows, major consumption points and sources of stored energy allows for modelling to predict the flow of energy under normal and excessive situations — allowing automation to be used to change the configuration of the smart grid balance of consumption and production.
A smart grid can help to optimise infrastructure expenditure. Better balancing of loads and better planning for the impact of microgeneration can lead to a reduction or deferral of capital expense, through better use of existing assets.
Proactive maintenance can also be achieved, by spotting the potential problems as they develop and resolving them, rather than waiting for an outage and having to replace equipment. And information that supports faster identification of problems and root-cause analysis can help streamline operations.
Aligning grid operations with social impact
Traditionally, the priority of outage resolution has been based on the technical characteristics of the problem. With social and sustainable living being a driver of the smart city, the impact on the community of operational activities needs to be more closely considered. For example, fixing an outage may be given higher priority if one of the impacted consumers is an aged-care facility, and lower priority if it impacts a business estate outside of office hours. While this is a more sophisticated use of smart grid data, the information needed to achieve it already exists today.
Characteristics of a smart grid
A smart city needs a sophisticated smart grid system, if the positive social, lifestyle and sustainability targets are to be achieved. There are a number of characteristics that need to be achieved.
Security must be one of the top priorities of the successful smart grid. It will need to achieve the following features:
- Security must always on and not able to be disabled.
- It must be standards based, so that it can be independently verified.
- It needs to provide intrusion detection, since just focusing on the perimeter is insufficient against smart attackers.
- It needs to be compartmentalised so that penetration can be restricted, should it occur.
Smart grid physical components must be intelligent and multifunctional. So-called ‘smart meters’ that only have the purpose of enabling better billing information will not support the functionality required to truly achieve a smart grid.
In fact, each node in the smart grid needs to be a computing resource, allowing innovation at each layer in the infrastructure. For example, integration with the home or business is a key role for the meter, and control of overall consumption of feeders is a role for the data concentrator, but the true innovation will arrive when these compute resources share information.
The smart grid must communicate large volumes of information from the meter to the monitoring, analytics and decision-making platforms. Today’s IoT technologies, involving cloud technology to enable big data analytics, will make this possible provided the devices combine ease of set-up, ease of maintenance and low cost per interface.
Existing grids are designed based on the assumption that the flow of energy is from a centralised generator to the consumer and the flow of information is from the meter to a billing system. For a smart city, the smart grid needs to be omnidirectional:
- Energy can be generated locally and consumed or stored locally.
- Meters can be controlled to turn supply on and off, throttle supply, control relays, control other devices and connect to other meters to gather other utility information.
- Information can flow between the meter and other devices in the home.
- The smart grid must support the omnidirectional nature of energy and information.
Building such a huge collection of interconnected systems as will be found in a smart grid means that automation, command and control, and generation of responses require the close integration of numerous information sources, analytics tools, algorithms and controllers. The smart grid needs to be open and standardised, allowing all its features and capabilities to be exposed to suitably authenticated and authorised systems.
And, it is not just about electrical energy — smart utilities supplying gas and water also need to be considered in the same way.