Optimal control strategies for water distribution systems.

摘要

The optimal operation of a water distribution system is an extremely complex problem which, when solved, offers the propensity for significant monetary savings and improved overall operations. In the context of this dissertation, the optimal operation of a water distribution system refers to the selection of a pumping policy which minimizes pump energy costs while maintaining system-wide pressures and storage tank water levels within acceptable limits. Fortunately, there are methodologies, in the form of optimal control models, which are capable of reducing the electrical consumption at water supply pumping stations. This dissertation details the development and application of several methodologies capable of providing optimal control.;Three modes of water distribution system operation are examined: (1) instantaneous operations, (2) incremental operations, and (3) extended period operations; and optimal control methodologies are developed for each mode. For instantaneous operations, a rank ordering approach is developed for the case where boundary and loading conditions remain fixed over time. For incremental operations, where loading conditions remain fixed and boundary conditions vary over a short time period, an innovative rank ordering approach is developed. The approach evaluates the hydraulic and economic performance of multiple pump groups which are capable of meeting a required pump station discharge. Finally for extended period operations, where both loading and boundary conditions vary over a daily operating horizon, two control methodologies are developed. The first approach integrates the rank ordering methodologies developed for the incremental operations within the framework of a multi-state Dynamic Program algorithm. The second technique employs the DFP variable metric optimization algorithm using pump operating time as the decision variable. All methodologies utilize an existing network simulation model to predict the state of the hydraulic system for various loading and boundary conditions. The control models are applied to actual water distribution systems to gauge their effectiveness in controlling electrical costs at water supply pumping stations.