Balancing
For the national gas transmission grid to operate in a stable and reliable manner, the entry gas and exit gas should be more or less in balance. GTS is responsible for the balance in the whole system. To be able to perform this task, GTS has developed a set of rules. Shippers who are active on the national transmission grid must comply with these rules. This so-called balancing regime is aimed at a system in which each individual shipper ensures that the entry gas and the exit gas within his portfolio are balanced. There is a balance when the difference between the entry gas and the exit gas stays within specified tolerance limits. A time shift standard of two hours will apply here between gas realised at the entry point and gas realised at the exit point. This time delay is the result of the buffer effect of the transmission grid: a change in the exit time is absorbed in the first instance by the grid, the entry should be adjusted to reflect this change shortly thereafter. This means that the required balance will be achieved when, within a portfolio, the difference between the sum of the realisations at the exit points during hour t (for example 08:00 hrs – 9:00 hrs) and the sum of the realisation at the entry points during hour t+2 (in this example: 10:00 hrs – 11:00 hrs) lies within the allowed tolerance limits.
GTS will check the ‘hourly difference’ determined in this manner against three tolerance limits (also refer to 4.2.):
- Hourly tolerance
- Cumulative tolerance
- Daily margin
When the hourly difference exceeds the hourly tolerance, this will be considered an hourly imbalance. When the aggregate hourly differences exceed the cumulative tolerance, this will be considered a cumulative imbalance. When the cumulative hourly difference at the end of the gas day exceeds the daily margin, this will be considered a daily imbalance.
