The universal meter data modem Skalar has been expanded with a new application software module, Skalar.online, which enables the Skalar to deal with online metering on a one-minute interval basis. The application is available for PSTN, ISDN, Ethernet, and GSM, on which the TCP/IP-based GPRS network can be used. The low-cost level of GPRS enables online monitoring at customer and intertie locations, where previously cost-intensive leased lines had to be used.
The Skalar is an intelligent meter modem for wall- and DIN-mounting on the clamp area of the meter. An open JAVA platform allows a variety of energy-specific applications and solutions to be run at the meter location.
GPRS: AN ALTERNATIVE TO COST-INTENSIVE LEASED LINES
The new application, Skalar.online, makes another level of measurement sites available for online monitoring. Until now, the high installation and operation costs of wired communications have not been economically justifiable, and pulse-based communication of actual load values has mostly been used in this customer and measurement segment.
HOW IT WORKS
The Skalar metering device tracks actual load consumption information from up to 6 pulse output channels of meters on site. The data is stored in the Skalar and sent to central data processing. The transmission cycles can be defined in a job list for each device. Due to the limited data throughput of the GPRS radio connection, GOERLITZ has defined an optimised data protocol – MPX – to limit the amount of online metering information and make it easy to handle.
Central data collection is done with the utility’s standard FTP data servers. The use of VPN connections and tunnelling through the GPRS network enables confidential data handling, even when standard Internet resources are employed. Most of the GSM providers offer these VPN connections at special ‘metering’ rates, with discounts for utility applications. German Telekom’s T-Mobile, for example, offers the connectivity of up to 1,024 meters in one central VNP connection for a flat rate of 50 Euros.
A central software application, such as the EDW3000, converts the individual MPX data files from the online meters into standard data formats such as LPEX, MSCONS or any other individual format that complies with the local SCADA or EDM system.
Beside online monitoring and resource planning optimisation to balance energy demand, the additional SCADA functions – such as alarms in case of malfunction, event tracking or switch control management – can easily be carried out with the new Skalar.online application on a low-cost basis.
The intelligent auto-scheduling concept of the Skalar helps to save communication costs. The device can be set to handle individual time zones of a day with separate data retrieval resolutions. This allows a user to set a more detailed resolution for the peak phases of the day, which carry a high risk of exceeding maximum load, than for the off-peak phases. For example, the time around noon plus or minus 2 hours can be defined to send the load data every minute, whereas in the morning and the afternoon 5-minute intervals would be sufficient, while at night values could be sent at 15-minute intervals.
FIELD INSTALLATIONS AT BELGIUM'S SPE UTILITY
The new LCM concept for reduced-cost meter data collection is performing well in Europe. The Skalar-based communication technology has been implemented in several European projects, such as at Belgium’s SPE.
SPE, based in Seraing, is one of Belgium’s leading power producers. The utility has implemented a couple of Skalar meter reading devices in their power generation facilities. Belgium’s ‘Mobistar’ was selected as the GSM network provider to set up a GPRS-based VPN connection from the meters directly into SPE’s network.
One major advantage of the system is the short response time of the meter device, which allows additional applications such as switch commands and remote control of production capacities.
In addition most of the German utilities have started pilot projects with the new Skalar technology based on GPRS-connections.