Smart Meters help in serving the end customers in the best fashion possible and also facilitate in meeting the growing demand for power.
The power sector in India is undergoing a phenomenal change with special focus on the distribution segment, where the energy losses are exceptionally high. The power distribution segment is witnessing a change in the way meter data is being collected and subsequently used for billing the end electricity consumers.
From manual meter reading system to Automatic Meter Reading (AMR) system and finally to Advanced Metering Infrastructure (AMI), the change is evident. This change calls for electronic meters with enhanced functionality commonly known as Smart Meters.
Why Smart Meters?
Demand Side Management, Demand Response, Load Control & Load Curtailment are few of the highly discussed concepts of the day. These programs and concepts are needed in order to sustain the growing appetite for energy consumption and serve the end power consumers better. One of the most important and starting point; as well as end point for implementing these concepts is by upgrading to smart meters.
The present meters installed at consumer premises is not suitable for realisation of demand side management. The traditional meters are electro-mechanical meters which are being replaced by electronic meters. Even though these meters are electronic, these are more suited for Automatic Meter Reading (AMR) and are not applicable for Advanced Metering Infrastructure (AMI) since these electronic meters are designed to provide only cumulative reading and perform few AMR functionalities.
Features of Smart Meters
Though there is no mandatory features that if incorporated or omitted can qualify a meter as a Smart Meter, more the number of below features, more close it will be for realisation of AMR/AMI and subsequently to the Smart Grid. These features are generally applicable to all machines. But in a few cases, these features can be very specific to single phase and three phase meters used for residential consumers. Import Export Metering- The traditional residential meters are Forwarded energy recording meters, that is, even in case of export of energy from the consumer to grid, this meter treats this as import of energy. This provision of forwarded metering was set in to take care of theft, where consumers would interchange the Phase and Neutral wires and give a false indication to the meter for export of energy.
However, with rooftop solar panels becoming more popular, this way of measurement of energy needs to change and the concept of Net Metering needs to be introduced.
Net metering is an electricity policy for consumers who own (generally small) renewable energy facilities (such as wind, solar power or home fuel cells). "Net", in this context, is used in the sense of meaning "what remains after deductions" in this case, the deduction of any energy outflows from metered energy inflows. Under net metering, system owners receive retail credit for at least a portion of the electricity they generate. In the Indian context, majority of the smart meters still need to be forwarded meters to take care of tampering. However, there needs to be a provision in the meter to be configured as ´forwarded metering´ or ´net metering´. It is important to have this configurability at the field in order to ease the process of meter installation. Moreover, there should be a provision to remotely activate and de-activate net-metering. This special configuration message needs to be passed on to the MDM (Meter Data Management) software, in order to apply special validation and estimation rules. Open Protocol: Meters used currently are with propriety protocol where vendor provided modem and software is required to read these meters. However, in order to have an interoperable solution and to integrate AMI components with ease, it´s necessary to have the protocol details of the meter. Therefore it becomes necessary for all smart meters to follow a common metering protocol standard. This requires the meter to be read via any software and any communication technology but with adequate security checks.
In the Indian context, it´s more appropriate to use a global communication standard but this needs to be modified as per Indian conditions and requirements. It´s also necessary that smart meters should have special codes that are shared with the software integrators in order to take care of authenticated transactions (time set, firmware upgrade, etc).
Home Area Network (HAN) Device
There needs to be a provision for close interaction between the consumer and the utility regarding dynamic pricing of electricity, alerts, notifications, broadcast commands, etc. This calls for engaging the customer for demand response activities and hence there should be a way to integrate a display device with a smart meter.
In the Indian context, an interactive display unit will find applicability only if the device is highly cost-optimised. Moreover, the mode of communication between the meter and display device is of prime importance, as this has cost and performance-related implications.
Provision of communication module
Traditional meters were read manually by a meter reader but with advent of cost-effective communication technologies, meter reading is undergoing a process of automation. Hence a smart meter needs to have a provision for integrating any desired communication module inside the meter body. This provision for internal communication module is applicable only for single phase and three phase whole current meters, this is because the quantity of these meters are large and easily justify a business case for changing the form factor of the meter. For upper metering segment meters, it will suffice the purpose if external communication modules are hooked to the meter.
In the Indian context, having a modular enclosure may increase the cost of the meter significantly. Moreover, this will expose the meter to tampering activities, pose problems of additional sealing arrangements and risk failure in various mechanical tests. Therefore it can be safely said that having an integrated communication module, would suffice the purpose and can come close to the price expectations of a smart meter for the Indian market.
Firmware upgrade provision
With so many algorithms in a smart meter, there will always be a need to change the software program of the meter without erasing the old data from the meter . Also to take care of field reported bugs, feature enhancements, and changing regulation/policies either in full or partial firmware of the meter may be upgraded. This feature will gain more importance in case of utilities expecting high meter life expectancy.
In India, firmware upgrade may be required but only partially. This feature has cost implications, leading to addition of some hardware components and also complex software algorithms inside a meter. Smart meters should definitely have the provision to upgrade features and functionalities by adding patch software.
AMI Meter software features
Loads of algorithms, logics and functionalities needs to be built up to complete a smart meter- like taking care of various tamper conditions, method of logging demand and load survey, recording of energy channels, quality of supply etc. Hence as compared to traditional meters, smart meters need to be functionally rich.
Connect/Disconnect-With traditional meters, the only way for load curtailment in shortage of power was complete blackout of a specified area. This needs to change for an AMI solution, where utility can selectively disconnect and subsequently reconnect in case of power shortage, non-payment of bills, move-in move-out and even in case of demand over-shoot. In India, connect/disconnect is a must-have feature. Without connect/disconnect, the prevailing problem in the Indian context cannot be met. This feature needs to be provided with additional security features like immediate/random disconnection. As a method of safeguard, the meter should first go in the ´arming mode´ before a re-connection; However, its applicability in Indian context doesn´t seem very reasonable.
Revenue Protection: Meters are like a cash box for the utility, it needs to be safeguarded from all sorts of theft. Hence a meter needs to be protected from old tampering methods as well as new type of intelligent thefts like Electrostatic Discharge (ESD), high voltage sparks, neutral disconnection, neutral disturbance, magnetic influence etc. In the Indian context, given the rampant pilferage of energy, revenue protection is of prime importance. For single-phase meters connect/disconnect relay needs to be provided in both the phases. In case of internal mesh radio communication module, ESD/Spark immunity has to be traded off. This is because it´s technically difficult for both the features to co-exist. Similarly features before incorporating need to be validated in view of revenue protection of the meter.
Smart meters needs to send an outage notification to the back office in case of power outage. This feature is commonly termed as a ´Last Gasp´ feature and helps utilities to provide better services to end consumers where all sorts of outage notifications are sent without the end consumer having to inform the utility.
In the Indian context, having such a value added feature needs to be validated especially when the target is to have a cost-optimised meter applicable for mass roll out.
Ways need to be devised to take care of data communication between meter and communication module in secure and protected manner. Therefore all sort of security features like DES keys, passwords, encryption need to be built in a smart meter. Spoofing and network hacking are new related technical jargon that need to be taken care of in Smart Meters.
The author, Imran Khan, is a domain expert on Advanced Metering Infrastructure (AMI) and Smart Grid Applications. He is working as Solution Architect & Business Development Executive for Smart Metering Solutions in Siemens Ltd.