Advanced metering infrastructure (AMI) is expected to help in providing a more reliable and better quality of power to end-users as well as assist in the reduction of peaking load and aggregate technical and commercial losses in the electrical distribution system. AMI is the next step in the automated meter reading (AMR) domain. It provides two-way communication capability and is the basic building block for smart grids.
The advancements in information and communication technology (ICT) have paved the way for the introduction of AMR technology in electrical metering, greatly reducing the efforts involved in manual metering and billing collection for utilities. AMR has been implemented by many utilities in India for high tension (HT) customers, feeder meters, transformer meters, etc. The Ministry of Power’s (MoP) flagship Restructured Accelerated Power Development and Reforms Programme (R-APDRP) has helped Indian power utilities take AMR up to the distribution transformer level.
AMR is a precursor to AMI and the latter opens up newer possibilities for the remote control of meters at the user end. AMI will provide two-way secure and reliable systems that will be utilised to communicate from the user end to the utility end, using smart meters. It will transform the present electrical metering infrastructure and further help in the deployment of the smart grid.
Costs and benefits
Implementing a new technology involves a higher cost during the initial stages. This was experienced when electronically communicable meters were introduced into the utility network. But ease of billing, greater transparency and improvements in the recovery of energy bills soon showed the much larger benefits of the technology.
Some utilities initially tried AMR, but most of them failed because of the plethora of non-standard communication protocols. The use of standards-based solutions, volumes of usage, maturity levels of technology and know-how, and reduced costs have paved the way for the large-scale implementation of AMR in an economical way.
It is foreseen that AMI-based solutions will also follow the AMR path. The cost to utilities may be higher at present but these will tend to fall in the near future, provided standards-based AMI products and solutions are chosen. Across the world, many countries are going for proof-of-concept projects for AMI to bring in more standards based on the results achieved from these projects. The success of AMI projects is high when standards-based solutions are adopted, which help in scalability, interoperability and sustainability.
AMI costs relate to the deployment of AMI-compliant energy meters, communications infrastructure, associated IT systems, integration of heterogeneous systems, operations, project management, deployment of demand-response systems, and replacement of electronic systems. An AMI cost-benefit analysis is undertaken for an investment period, say, 15 years. Generally, the benefits associated with the technology comfortably exceed the costs involved.
Infrastructural requirements
AMI, a data and information transportation network encompassing the source and destination entities, is a mandatory subsystem of any smart grid project. It is a combination of various technologies. A generic AMI comprises four building blocks, which are as follows:
- Head-end system (HES) – the IT system
- Wide area network (WAN) – the backbone communication layer
- Smart meter network (SMN) – the cluster of smart meters and data collecting unit (DCU)
- Home area network (HAN) – the network of customer premises appliances
These blocks constitute AMI infrastructure which is designed to exchange data, events, commands and utility messages almost in real time.
HAN: Confined to customer premises, it is a cluster of devices that helps the HES reach appliances for monitoring and control. HAN could be implemented with communication technologies like IPv6 over low power wireless personal area networks, ZigBee, programmable logic controllers (PLCs), Wi-Fi, Ethernet and the internet of things (IoT).
SMN: This is also called the neighbourhood area network or field area network. It is a cluster of smart meters at the customer premises networked through a suitable communication medium via a DCU. SMN could be implemented with communication technologies based on low power radio frequency, ZigBee, PLCs, Wi-Fi and optical fibre. It may require appropriate tailoring as per the site conditions.
Smart meter: A smart meter is a composite unit with a static energy meter, communication module and control element. It can perform functions like measurement, computation, event capturing, storing, communication and control. It is required for providing the data and information needed for various smart grid applications.
DCU: The DCU generally gathers data from all the smart meters under its logical group, stores and forwards this to the HES and synchronises the real-time clock of group meters. The DCU will also have communication ports – one each for SMN and HES connectivity.
WAN: This is the third layer and is introduced to bridge the SMN and the HES. It is generally a public communication network with large bandwidth for transporting large volumes of data.
HES: This is the IT system consisting of servers, storage, workstations, routers, firewalls, etc. With reference to AMI, the HES relies mainly on meter data acquisition system (MDAS) and meter data management system (MDMS) modules.
Utilities’ experience
As we have seen a rapid change in ICT in recent times, there is a sea change in metering technologies as well with the emergence of AMR and AMI. The replacement of all meters with state-of-the-art meters will cost utilities enormous amounts of money. In any utility network, especially in the power distribution network, the majority of meters are for low tension consumers and the other portion for HT consumers, which account for a major chunk of the revenue billing. Hence, utilities try to implement the best available technologies for HT consumers and gradually expand to other categories of consumers.
With further advancements in technology, utilities did move forward to implement AMR, which till recently was a challenge as meters were not following a standard open communication protocol, and getting data from different makes of meters was next to impossible in a homogeneous environment. In India, the need was felt for a standard open protocol. The Central Power Research Institute (CPRI) is a frontrunner in the country for technology development in this area and is helping standardise metering. The CPRI took energy meters in almost all forms under consideration and metering standardisation became a reality when its contribution and suggestions were accepted and the companion specification standard was released by the Bureau of Indian Standards as IS 15959. It was further mandated by the MoP to adhere to the companion specification for procuring meters under the R-APDRP.
In India, power utilities are taking the lead when it comes to the adoption of AMI technology. Metering automation under the R-APDRP has most of the AMI functionalities. It must again be emphasised that standards-based implementation will be key to sustainable AMI solutions and will help utilities in future scale-ups. Projects under the R-APDRP, which implement AMI system energy meters based on the open communication protocol, that is, IEC 62056, are facilitating easy integration.
Preparing for the future
AMI is one of the basic building blocks in the smart grid framework. At present, most meters, especially domestic consumer meters, are of the dumb or non-communicable type. These are to be replaced with two-way communicable types of meters, a prerequisite for any AMI implementation. It is again emphasised that utilities should go with standards-based AMI solutions at the meter and DCU levels so that interoperability issues are avoided. The proper use of standards-based AMI system components like MDMS, DCU and metering and communication systems will help to find proper solutions for successful AMI implementation.
Few utilities are aware of the available standards and requirements of communication protocols. Any dilution in these aspects will lead to non-standards-based AMI implementation, which will be a bottleneck in the large-scale deployment of the technology.
Role of metering solution providers
Metering solution providers need to ensure that their solutions are compatible with the new technologies and functionalities envisaged for AMI. Solution providers should not only provide standards-based solutions but should also encourage their adoption. Suitable AMI systems, keeping in mind scalable requirements, should be offered by solution providers to utilities as once the telecommunication service provider and the communication technology are frozen, it is very difficult to migrate to different ones. The MDAS provided by solution providers should have a commonly used database from which collected data can be used by various other applications and packages. For its successful implementation, AMI should always be supported by the testing and certification of various components and technologies by a third-party laboratory to ensure compliance with standards.
