Mixed simulation-state estimation of water distribution systems based on a least squares loop flows state estimator

This paper presents combined simulation and state estimation algorithm for water distribution systems based on the loop corrective flows and the variation of nodal demands as independent variables and it optimizes the Least Squares (LS) criterion. The combination of the two algorithms for simulation and state estimation is based on the delimitation of regions in the water network that are state estimated while for the remaining parts of the water network the simulation task is realized. The sizes of the respective delimitations can be based either on the hydraulic or topological distances from the real pressure measurements, flow measurements or measured nodal consumptions. The delimitations are realized through modifications of the inverse of the upper form tree incidence matrix which is used in order to construct the respective state estimated or simulated water network areas: the simulated nodes and pipes have the corresponding incidence columns zeroed in the inverse of the upper form tree incidence matrix while the state estimated nodes and pipes keep the values of their incidence described in the corresponding columns of the inverse of the upper form tree incidence matrix. The combined novel algorithm can be also applied to regions of water distribution systems which contain low pipe flows so that to avoid any convergence problems in the numerical algorithm. It results an efficient and effective novel mixed simulation-state estimation which is implemented on realistic water distribution systems. (C) 2013 Elsevier Inc. All rights reserved.