AMR in Munich
The Munich Trade Fair Corporation in Germany was planning to build a new exhibition centre – the New Munich Trade Fair Centre. It would contain 13 exhibition halls, an open field area and several fixed business areas for restaurants and the like.
The corporation knew from previous experience that energy metering and maximum demand control were not usually handled efficiently enough during fairs and exhibitions. While energy efficiency was an important feature in the design of the new centre – for example, the roof incorporates the world’s largest solar power array, with a rating of 1 MW – a need for exhibitor-specific metering was also apparent. This in turn meant there was a need for automatic meter reading. The corporation wanted a comprehensive metering solution which used modern technology, and which was also flexible and easily expandable.
The centre’s energy consumption can reach that of a small town. The specifications for the new system included the ability to meter the electricity used by each exhibitor in each of the 13 exhibition halls during every trade fair, as well as that used by the ancillary facilities.
The corporation decided to purchase the Avalon metering system from Enermet. Avalon is a remote reading system which transmits data from meters over low power cables to a central monitoring computer. Customisation of the system specifically for the centre began early in September 1997, and the installation and configuration of devices was started in December the same year. Final completion was set for August 1998 – by which time the system had been used during two fairs, with highly satisfactory results.
ALLOCATING COSTS ACCURATELY
A central requirement for the owners and managers of an exhibition centre is the ability to allocate costs accurately. Exhibition centres have traditionally charged each exhibitor a standard rate, or alternatively a rate in proportion to the stand area. Electric power is a major cost item, and the ability to invoice each stand based on actual consumption benefits both exhibition organisers and exhibitors.
The Avalon integrated system has been designed to read 4 000 stands simultaneously in the first stage, and 10 000 additional stands in the next stage.
Each stand is equipped with a K420NN electronic meter. Using the standard output of the meters, measured consumption data is transmitted over the low voltage supply network to data concentrators, each serving a group of stands. From the concentrators the data is transferred to the central computer of the Avalon system by conventional communications cable.
The system is based on LON PLC technology. The server has 108 modem connections to LON concentrators all over the exhibition area. The longest modem lines at the moment are 2 km. In the open field area there are 105 LON repeaters installed in caves, to guarantee effective communication using the longer cables.
Some 1 000 meters are fixed installed in NSHV rooms, while the remainder consist of freely removable exhibitor meters. The concentrators for these exhibition meters are located on busbars; in the open field area the concentrators are in transformer houses.
The communication with the PLC C band is reliable and fast – reading one register value takes roughly 0.7 seconds. The longest supply cables without repeaters measure about 200 metres, and there have been no noise problems.
Exhibitor flexibility is of course of major importance, and therefore the position of exhibitor meters often changes for every fair. The new information is collected during installation with handheld computers reading bar-codes, and is sent to the Avalon server via LAN. The Avalon system can handle up to three fairs simultaneously, and an automatic route search program will find the optimal route for every meter. Meter values are stored in the Oracle database and there is a view of this data via LAN for the billing system.
The AVALON system configuration for the Centre Avalon MCU software Over 4 000 electronic electricity meters Over 4 000 low voltage network terminal units 108 MC100 concentrators 150 ME10 repeaters 216 fixed connection modems 8 multiplexers in 16 lines 1 server 2 workstations 35 handheld units 4 PCs for downloading the handheld unit data