Consumer data, especially small "home" consumers, are read once a year, only. When executing computations with small consumers their hourly values are deduced from yearly readings using standardized methods (standard load profiles, SLP). In all computations — when SLP’s are involved — it must be kept in mind that this method influences the accuracy of the computing results when a short time period is considered. Opposite to the former small consumers the big consumers are measured and registered continuously; so computations can be made very accurate even in short periods.

2. Operational aspects

2.1 Smooth operation goal

Network operators favor smooth operating conditions for a number of reasons:

• Avoid sudden pressure changes (could generate shock waves, higher gas velocity)

• Avoid bigger and many flow changes (leads to pressure changes, regulator instability and wear out)

• Deliver/provide constant gas quality (i. e. colorific value), (operate within allowed limits).

In reality more or less big changes are likely to occur each hour (minute) due to changes of the consumption, scheduled feed-in according to delivery contracts, natural variation of gas quality of gas sources/production fields.