Today there is increasing activity towards implementing solutions to collect energy consumption data and manage energy meters from a remote location. These systems are called automatic meter reading (AMR) or management (AMM) and are intended to give an energy provider more control over its business by providing real time information on the end consumer behaviour.
We will call these systems remote meter management or RMM. Maintenance, energy consumption control and customer service can be greatly simplified and improved by a two-way communication system. This article provides a quick overview of the benefits of remote meter management, followed by a presentation of communication technologies applicable to energy metering and their benefits.
Managing or reading the energy meter remotely has been a subject of discussion for many years. Some of the expectations are now taking shape, with companies deploying electronic energy meter systems with communication capabilities. These projects have different scales and ambitions, but recurrent themes have been used to justify them.
Communication with the energy meter opens a new channel between the energy provider and its customer. This channel is non-invasive for the customer and offers new opportunities for better service and accountability. For example, billing on actual meter reading, change of contract or energy provider upon request and remote connection/disconnection is possible with RMM solutions. Meter communication not only enables these services, but also opens new opportunities for energy providers and their customers to do business. For example, with energy costs rising, intelligent energy meters with communication make the evolution to a distributed energy grid, where each home can be a source of power, a rewarding experience for home or business owner.
The cost of generating energy does not lie in the MW of power used all the time every day, but in the peak of demand that occurs during a day, a month or a season. A two-way communication network allows the energy provider to actively change the load by potentially affecting the meter configuration. By dynamically monitoring energy consumption in real time, the energy provider can prevent the demand from outrunning the supply by shutting off non-critical loads and thus reduce the need to build additional power plants. This monitoring can also help to discover a tampering situation and ensure that all the energy produced is being billed properly.
The energy provider can offer some incentive to residential customers to change their usage patterns by changing their pricing structure. By instituting a time of use, or multi-tariff system, residential customers can be charged a higher rate during peak usage times, leading them to consume more energy during off-peak times. Maximum demand, another billing strategy, attempts to conserve overall usage by billing based on maximum usage. Energy meter communication that can provide instantaneous energy consumption information is the solution of choice for flexible billing structures without costly repurchase and reinstallation of meter technology.
GOING BEYOND THE ENERGY METER
With communication to the energy meter available, the energy provider could offer meter management services for gas and water meters as well. A wireless network between all of the serviceable meters in a residence, with the energy meter acting as the gateway, would benefit all three utilities. Going beyond providing basic energy services through this new channel to include, for example, Internet or phone may be technically possible, but other communication channels like cable, phone line or ADSL are more naturally equipped and competitive for these purposes.
COMMUNICATION FOR METERING
The requirements for a meter communication solution depend on the amount and frequency of data collected from the meter and the type of services required by the system. A simple one-way network allows the utility to collect usage information, but not to manage the meter and provide the added services mentioned above. Two-way communication between the meter and the energy provider gives the most versatile system, not only because of its features but also because of its potential upgradeability.
TODAY’S TECHNOLOGY OPTIONS
There are several main meter communication technologies – powerline carrier (PLC), short range radio frequency, and GSM/GPRS (Global System for Mobile communications/General Packet Radio Service).
PLC technology modulates data onto the power line. For energy meters, PLC is predominantly a narrow band communication. It has the advantage of using an existing reliable medium, the power line, that does not need to be built or altered to achieve meter management. A major benefit to utilities is that they own the infrastructure, and so do not incur an additional per message cost with PLC communication. PLC communication is generally low speed – 10 kilo-baud per seconds or less and reliable when the link is made.
Short range RF generally uses the industrial-scientificmedical (ISM) bands at 433MHz, 868MHz and 915MHz. RF bands can be bought for specific purposes if required, but this limits the opportunities to use existing commercial technologies developed for open ISM bands. One of the main challenges of developing a short range RF solution lies in developing a dynamic network that can handle changes in the quality of the RF communication channel. The solution is a combination of the right hardware and a choice of network topology – Star, Redundant Star, Mesh or Tree. As the short range RF bands are licence-free, there is no per message fee involved with this technology.
GPRS uses GSM wireless bands to provide an ‘always on’ connection. This two-way communication channel allows data transfer at around 100 kbps. GSM provides the ability to send short messages using SMS (short message service), creating an efficient one-way channel. The RMM provider does not own the infrastructure for GSM or GPRS, so there is a fee for every SMS message sent. However, the RMM provider benefits from the constant improvement in GSM/ GPRS technologies and network coverage, with no investment in its infrastructure.
Figure 1 – Typical RMM network arrangement
RMM NETWORK SOLUTIONS
The goal of RMM is to send data from the meter to a central location, but this connection does not have to be in one hop. Frequently there will be a stop in between the meter and the central unit – the concentrator, which can be fixed in the neighbourhood to collect data from the meters and relay it to the central unit. Adding a concentrator to the network allows more flexibility to create a cost-effective solution. An inexpensive technology such as short range RF could be used to send data from the meters to the concentrator, while a more expensive technology like GPRS is used to send the data from the concentrator to the utility. Implementing a hybrid RMM solution allows the best technology to be used, depending on the environment. In fact, a communication technology can be preferred for a location without the need to adopt it for the complete RMM solution. RMM is not concerned with a specific communication technology but is the complete solution to connect any individual meter in a local loop to a central location – see Figure 1.
OFF-THE-SHELF COMMUNICATION SOLUTIONS
All the communication technologies applicable to RMM are coming down in price as the technology matures and becomes more accessible. More offthe- shelf designs are becoming available, with less technical expertise required to implement them. The key to success in these implementations lies now less in the technology itself than in the networking layers used to interconnect them. Turn-key designs provide an easy link between master and slave and a networking solution for a connection between the central station and the individual meter.
For short range RF, where there is little protocol standardisation, one of the biggest challenges is in deciding on a robust protocol. Encoding, repeating, error detection and correction are key basic features of an RMM modem that are added by either the system provider or by the ISM modem chip provider. For example, Analog Devices not only provides the most sensitive short range RF transceivers in its class (ADF7020 for ANSI and ADF7021 for IEC markets) but accompanies them with a basic networking solution. The ADIismLINK tool allows wireless product designers to transfer data between multiple slave units and a master node without having to spend time developing their own protocol.
The ability to provide a complete RMM solution becomes more valuable as the technology becomes more intricate. GPRS requires many layers of protocol, including TCP/IP. Also, data can be transmitted securely with HTTPS and PKI protocols using GPRS. To reduce the complexity of including this technology in an embedded system, many companies provide GPRS modules that include hardware as well as TCP/IP stacks and other software libraries. Siemens offers GPRS modules that are easy to combine with other systems. Their TC63 and TC65 modules use the Analog Devices SoftFone chipset and are recommended for RMM.
Of GSM/GPRS, short range RF and PLC, narrow band PLC is the most specialised RMM communication technology. For this reason, little innovation has been made in terms of raw PLC modem technology. Most current narrow band component solutions use simple modulation and demodulation techniques (FSK) and signal processing developed many years ago. With the development of new RMM systems, it is only a matter of time before the benefit of today’s technology in terms of price and performance reach PLC solutions for energy metering. The breakthrough that can be expected from new development ranges from more reliable PLC connections to ease of implementation at a similar or lower cost than existing solutions.
The revenue and service opportunities made possible by remote meter management, suggest that communication to the energy meter is financially viable for commercial and residential customers. Communication technologies associated with the right networking solution are now understood and available in turn-key RMM solutions from various vendors. Analog Devices is proud to be part of this democratisation of high-tech solutions for energy meters by providing easy to use, high performance and affordable components for various communications technologies needed in remote meter management.