BALANCE-EQUATIONS ESTIMATION WITH BAD MEASUREMENTS DETECTION IN A WATER-SUPPLY NET

The development and the correct exploitation of a water supply net dem ands control increasingly dependent on flow measurements. The how bala nce permits detection of how measurement errors and evaluation of the performance of the net. If we detect an error in a how balance, we do not know which measurement device is wrong, nor find what type of erro r exists. The reconciliation of the measured data is not easy. To solv e this problem, we decompose it in the following parts: (1) Analysis o f the system, according to the observability and redundancy of the wat er net: we should obtain the matrix of system incidence, H. (2) Assign ment to the meters of measurement uncertainty: thus, we obtain the cov ariance matrix, R. (3) Estimate of water flows of the supply net, appl ying the maximum likelihood least-squares estimation to the set of flo w measurements using H and R matrixes. (4) Comparison of the estimated values with the measured values. In this paper, the authors use a pra ctical approach. We have selected a water supply net that illustrates well enough all the difficulties encountered in water flow measurement s. (C) 1998 Elsevier Science Ltd. All rights reserved.