Extended-Period Analysis with a Transient Model

To design and operate a distribution system, one must understand how it will perform when subjected to external hydraulic loads and demands. This paper presents a hybrid model that efficiently tracks the full range of hydraulic conditions, from steady state to waterhammer, in a system over an extended period by coupling a transient simulator with a reservoir routing scheme. The modelʹs procedure consists of running waterhammer simulations at the start and end of an extended time step to track the rate of filling of a systemʹs reservoirs and then using this information to update reservoir levels at the end of the time step. Beyond conventional level-of-service and capacity-assessment applications, the hybrid model can help the engineer link system unsteadiness to its associated costs in terms of design and operation. Extended period and worst-case simulations presented in a case study suggest that the hybrid model has a high routing accuracy and can be used effectively to identify the critical state which will produce the most severe transients in a system.