The Belgian gas and electricity market in Flanders has been liberalised since 1 July 2003. Inevitably this brought about the establishment of a few new market players, as in all countries where the energy market has been liberalised.

In the gas market, the following players can be considered:

Metering Company: collects meter readings, calculates derived data, exports and archives the consumption information.

Supplier: purchases and sells gas, prepares forecasts.

Transport Grid Operator (TGO): physically transports gas from the feeding points (Belgian Transport Grid) to distribution grids or large consumers connected directly to the transport grid. The TGO is also in charge of the operational balance of the transport grid, and assigning imbalance to corresponding TGUs.

Transport Grid User (TGU) / Shippers: responsible for the use of the transport grid and the nomination of gas consumptions in portfolio. They assure the balance between the amount of natural gas that is injected via the feeding points and the amount that is delivered at the reception station to the relevant distribution grid or large consumers.

Distribution Grid Operator (DGO): responsible for the physical transportation of energy via the distribution grid to consumers. The DGOs receive this energy from the TGO or nearby DGOs.

Net User/End User: energy consumer connected to the (distribution) grid.

 Metering Gas - System Setup

Belgium does not have large-scale gas storage to handle a temporary imbalance and shortage of natural gas.This means that balance and delivery are threatened if no appropriate steps are taken to guard the balance and take action when necessary. Gas Online went operational in October 2004; it provides the information to allow the TGO to monitor/predict the imbalance and to assign possible (future) imbalance to the responsible TGU/shipper. This information supply is a regulated task and is performed by Indexis, the federal meter reading company, for the mixed DGOs in Belgium.


Gas Online performs four basic functions:
1) Collects consumption values on an hourly basis. The local measurement devices are interrogated using the GPRS network and the IEC1107 protocol.
2) Calculates the gas consumption using the configured formulas and rules.
3) Sends the consumption data to the market parties that need it (suppliers, DGOs and TGOs, TGU/shippers) every hour. These market parties will process the data and evaluate the information, which allows them to adjust the balance in the gas grid.
4) Provides the measurements and consumption to the metering database of the meter reading company for further treatment (eg allocation, distribution and transport cost calculation).


The IMDMS (Independent Metering and Data Management System) manages the electricity and gas consumers (7 million consumers at full size, both residential and non-residential) and is responsible for the reading, treatment, storage and forwarding of the measurement and derived data for the mixed DGOs in the Belgian electricity and gas market.

Gas Online is a functionality that requires 24/7 uptime and needs to work autonomously of IMDMS. For this purpose Gas Online doesn’t run directly on IMDMS but on a special Real Time Database (DBR) which is a mirror (subset) of the IMDMS database. This DBR operates independently and is implemented redundantly. The IMDMS and DBR database are synchronised daily or ‘event driven’. Synchronisation occurs in two directions – to Gas Online asset and access register changes, to IMDMS measurements and status information.

The Gas Online system has a number of pre-processors which handle the protocols to the dataloggers and intelligent meters. In this case the IEC1107 protocol is used, running above TCP/IP on GPRS.

In the event that the whole main central installation fails, Gas Online falls back on the back-up installation or DRP (Disaster Recovery Plant).


Large consumer sites are equipped with a data logger and GPRS modem. The GPRS connection can only be set up via secure authentication (username and password). In practice two types of local systems are in place, one running on mains supply and the other on solar energy with batteries. The systems running on mains supply are continuously connected.

The devices that run on batteries and solar energy make a five-minute connection to the GPRS network (to safe power) every hour to send their data.

The GPRS connection can only be set up with the correct username and password. This information is passed via the GPRS provider to the IMDMS where the ACS (Access Control Server) checks the information. If the authentication was successful, an IP address is assigned and the GPRS connection can be established. During the connection period, the central system collects the measured values. The firewall on the IMDMS site protects the remainder of the data exchange.

Where a GPRS connection is not possible, an ADSL connection can be used as an alternative by providing an IETF 802.3 Ethernet port to the gas-volume  conversion device.

 Metering Gas - Availability


In the data logger at the consumer’s site, the data is registered every hour and sent to IMDMS Gas Online – not normalised measurement values, but net measurement values, consumption period and the device status. The data exchange between IMDMS Gas Online and the devices never occurs spontaneously, but only takes place at the request of the IMDMS Gas Online database. IMDMS can send two types of requests:

1) data read out (for normal readings)
2) programming mode (for time synchronisations and historical data).

The request for data is divided over two pre-processors for load balancing and redundancy purposes. If more devices need to be handled, or the period of the processing needs to be decreased, additional pre-processors can be configured. Only the data that was explicitly requested is sent. The preprocessors, in their turn, are responsible for the storage of the data into the database.

The protocol IEC1107 is used for the request/reply mechanism. The GPRS/IEC1107 protocol driver on the real time pre-processor receives a request from the IMDMS database and sets up a TCP/IP connection with the GPRS modem to open the IEC1107 connection. The connection is protected via a username and password which is available in the request message. Once it is set up, the protocol driver executes the requested items and sends the data.


The Gas Online functionality works autonomously. This means that, if the main IMDMS system is not available for any reason, the hourly interrogation and exports need to continue. Therefore Gas Online does not run directly on IMDMS, but on a special database DBR which is a mirror (for the Gas Online subset) of IMDMS. Via periodical or ‘event driven’ synchronisations, the device statuses (device changes, formula changes and so on) the access register (who is the supplier, shipper, etc) and measured data are kept up to date. The synchronisation frequency is adjustable. Data is queued when no communication between the two systems is possible.


The Gas Online system requires a high availability even during disasters and upgrades, so redundancy is of great importance and is available on every level of the system. In addition to the main installation, which runs on a cluster, there is also a Disaster Recovery Plant (DRP). The DRP installation is an online copy of the main installation, and is housed at a separate location.

The DRP set up is identical to the main installation except that it is not running on a cluster.

 Metering Gas - Sending of exports


The exports are sent in different formats to the various market players. The layout of the exports is either market regulated or bilaterally agreed between the market players. Currently CSV and EDI (UtilTS) exports are generated.

File Format

CSV files (Comma Separated Value) represent a common and easy-to-read format. The exports to the TGO are sent in the CSV format.

EDI (Electronic Data Interchange) is considered as the messaging standard for electronic data exchange of information about the electricity and gas market. UTILTS exports are Time Series Messages that contain the measurement data. For Gas Online, UTILTS messages are used to exchange the consumption information between supplier and DGO.

Communication Channel

FTP (File Transfer Protocol) and VAN (Value Added Network) are used as export channels. A VAN is the private network used in the Belgian energy market for data exchange in electronic data interchange (EDI) format. FTP is a common way of sending files over the internet. For exchanging CSV files, FTP is used as the communication channel.