Observer design for state and parameter estimation in pressure boosting systems for water supply

Abstract

Model-based control strategies for pressure boosting systems in water supply for high-rise buildings require the knowledge of internal system states and parameters which are not directly accessible for measurements with reasonable effort in practical applications. For that reason, the observer design is investigated in this paper for finite-dimensional system models of the dynamics of water supply systems. The corresponding state equations are derived as generalized network models which represent the overall system dynamics. The generalized network model involves pump-motor units as power sources, hydraulic capacitances, and fluid inertia which are described by separate sets of ordinary differential equations. These sets of ordinary differential equations are coupled by algebraic constraints derived from suitable balance equations. The applicability of a model-based state observer for the reconstruction of the volume flow rates in the individual pipeline segments as well as the pressure distribution along the fluidic network is demonstrated by numeric simulations. Moreover, the identification of nonlinear volume flow-dependent characteristics for fluidic resistances is demonstrated on the basis of an online applicable disturbance observer. Both observer models contain basic assumptions on the fluidic resistances which are refined online with the help of the presented techniques.