On-line monitoring for operational control of water distribution networks
This work concerns the concept of on-line monitoring and control for water distribution networks. The problem is simple to state. It is to produce a robust scheme that can continuously provide reliable information about the state of a water network in real-time and over extended periods with the minimum of operator interaction. This thesis begins by proposing a relational database schema to store 'asset data' for a water distribution network and asserts that asset data should be used as a basis for network modelling. It presents a topology determination algorithm and a demand allocation algorithm so that a mathematical model can be maintained on-line, with operator intervention only necessary to record the change of state of non-telemetered plant items such as switch valves. In order to provide a reliable on-line model of a distribution system, an investigation has been carried out into the methods available for modelling water networks and in particular, the inherent assumptions in these practices. As a result, new methods have been produced for network element combination and for demand allocation. These methods both support the database approach and enhance the robustness of the system by increasing the range of conditions for which the resulting model is applicable. For operational control, a new technique for state estimation is proposed which combines the advantages of weighted least squares estimation with those of weighted least absolute values estimation. The proposed method is tolerant to transducer noise and to the presence of large measurement outliers. However, the method is not limited in its application to water networks and could be applied to a wide range of measurement processing problems. Lastiy, a new topology based method for processing suspect data is proposed which can determine the likely causes using identifying templates. Thus a new approach to water network monitoring is proposed via an overall framework into which the various tasks of on-line operational control can be integrated. The exercise has resulted in the production of a core software package which could realistically be used in a control room to facilitate reliable operational control of water distribution systems.