Model calibration has always been a manual and somewhat time-consuming process with major costs. To facilitate model calibration, we have introduced a number of automatic trial and error methods, such as "Exhausted search" and "Genetic algorithms". However, it should be pointed out that the possible results and the number of calculations must be limited in advance. Therefore, you will often see that only a random result is calculated. The random result may correspond fairly well to the used measurements, but it may not apply to other situations. Furthermore, the quality of the solution may very much depending on the predefined limitations in the possible results. Consequently, the solution highly depends on manual judgment.
With 7-SEAS (State Estimation based Application Suite) these problems are history. The new state estimation technique enables you to find the optimal calibration values for the model and the distribution of leakages in only one calculation. There are no predefined limits to the possible results.
Figure 1. Model Calibration.
Enter the time series of pressures and flows from the latest measuring campaign into 7-SEAS. This is very easily done, if you have stored the time series in Data Manager. 7-SEAS then utilizes all the information from the measurement time series and calculates the following optimal values:
- Pipeline roughness or inner diameter for the individual pipelines
- Valve positions (open/closed) for shut-off valves, if unknown
- Geographical distribution of leakage flow in the network
If available, you can include additional information in the calculations as regards distribution of leakage, for example pipe material, pipe age, leak or burst histories, etc. When such information is stored in Model Manager, it is automatically transferred to 7-SEAS.