By Thomas Nickel

The energy industry is still vigorously discussing smart metering. The discussion not only concerns economic aspects, but also the meters themselves and their communication interfaces. Which meters must be installed and with what features? Which communication technology should these meters use? 

The data logger concept of the FNN Network Technology and Operation Forum within VDE (German Association for Electrical, Electronic & Information Technologies) is frequently referred to in this connection. The various installation options based on the Open Metering Standard also offer interesting alternatives, and at very low costs.

The Open Metering Standard is specified in Germany and is now being standardised Europe-wide. However, the radio data loggers and their various installation options are considered much too rarely for this purpose, even though they offer particularly interesting concepts that are definitely cheaper than the widespread concept of multi utility controllers (MUCs) proposed by the FNN Network Technology and Operation Forum within VDE.

FNN MUC: EXPENSIVE FOR FULL COVERAGE
The FNN MUC concept is based on one installation for each electricity meter. This means that one MUC is installed in each household to cover a maximum four media. With an expected price of €200 for the FNN MUC, this results in an investment cost of €50 per meter – a relatively expensive concept in the medium term and for a full-coverage rollout. These high investment costs will prevent or at least delay a rapid breakthrough of smart metering.

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The in-house fixed network scenario is based on one data logger per building
(Source DIEHL Metering)

INTERESTING ALTERNATIVE: THE OPEN METERING DATA LOGGER
But there is an interesting alternative to the present FNN MUC concept. The meter independent data logger Open Metering transceiver (OMT) can, depending on the installation scenario, read an average of 40 to 50 measuring points over Open Metering radio. Here the costs for reading up to 50 meters are only €5 to 10. Another advantage is that the GPRS receiver, a data logger with GPRS interface, has been ready for series production for over four years and can receive data from up to 1,000 meters. If 200 measuring points were reached per meter, the costs would be less than €5.

FLEXIBLE INSTALLATION OPTIONS FOR ALL ROLLOUT SCENARIOS
If a rollout is to be made in the medium to long term, the various installation scenarios of a radio-based fixed network should be considered. There are three different scenarios for meter independent data loggers.

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The small area fixed network covers streets of houses or housing estates (Source DIEHL Metering)

The in-house fixed network scenario is based on one data logger per building, irrespective of whether the building is a five-storey block of flats or a semi-detached or detached house.

A small area fixed network is based on smaller areas such as streets of houses or housing estates. Here the utility can use its own locations (e.g. cable distribution cabinets, transformer stations and other central points). The advantage is that this almost completely eliminates the need for the energy utility to negotiate costly agreements on suitable installation positions with building owners. In addition, the utility does not need to arrange access authorisation, and tenants or owners are not disturbed by maintenance work.

The third scenario is the wide area fixed network. This can receive several hundred to over 1,000 measuring points per location over distances of more than 1 kilometre from a few central locations using very powerful antenna peripherals.

THE COMBINATION COUNTS
An energy utility will probably not be able to cover its whole service area with a single installation scenario. The solution lies in the combination of these scenarios.

For example, a utility must read 100,000 households in its urban area by remote means. It first uses its own buildings for this, by installing a wide area fixed network in an administrative building or warehouse. This covers approximately 20% (20,000 meters) of the service area. The utility then uses its own cable distribution cabinets, transformer stations and other frequently distributed locations (also externally owned) for a small area fixed network. This reaches 60,000 meters. The utility covers the remaining 20,000 households with an in-house fixed network. The example shows that a majority of some 80% of the measuring points can be connected via data loggers located outside buildings.

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A wide area fixed network can reach up to 1,000 measuring points over a distance of 1 kilometre (Source DIEHL Metering)

ADVANTAGES OF THE OPEN METER SYSTEM
The advantages are obvious. Installation locations can be clearly defined, recorded and used. The medium to long term costs per measuring point are low. Moreover, the utility can use its own infrastructure, for example, electricity, internet and intranet, and the data loggers are to a large extent freely accessible in the fixed network. This reduces the coordination effort and the disturbance of building owners to a minimum.

OMT IN PRACTICE: AUSTRIA AND DENMARK
These scenarios are no visionary concepts, but are already implemented in practical and commercial applications in the international smart metering market. The largest Austrian district heating utility, Fernwärme Wien in Vienna, has decided on a fully automatic fixed network. First the meters in over 1,000 households were readable within hours using the walk-by mode of mobile reading. The conversion to GPRS receivers was completed in 2007. The data telegrams sent by the meter are now transferred automatically over the GSM network of any desired mobile telephony operator and transmitted to an FTP server by GPRS. The values transferred in the data telegram can be defined for different purposes. The fast and transparent recording of consumption permits future oriented energy data management, which makes reading uncertainties a thing of the past. Such a cost effective design does, however, require thorough project management and concept planning in advance.