Implications of Over- and Under-Determined Networks in State Estimation

The Unified Hydraulic Solver (UHS) provides an effective formulation to solve water distribution systems that are under-determined in terms of known parameters, and over-determined in terms of the sum of the known and estimated parameters. This UHS formulation allows for the full spectrum of analyses from the conventional hydraulic solution to state estimation, where model results can be reconciled with SCADA measurements. Furthermore, an effective SCADA data validation technique can be devised using the UHS formulation. This application of the UHS suggests however the need to understand the impact of the locations of the SCADA measurement points on the ability to detect demand deviations. Using an example network taken from the literature, this paper demonstrates that deviations occurring within an over-determined section of the network are more accurately computed than if the same deviations are located outside the over-determined section.