Surplus Power Factor as a Resilience Measure for Assessing Hydraulic Reliability in Water Transmission System Optimization

Abstract

The hydraulic reliability of a water distribution system (WDS) can be improved by increasing the resilience to failure conditions. In previous research, numerous measures have been developed to quantify network resilience, which has been consequently linked to the hydraulic reliability of WDSs. Often, the difference between the output pressure head and the minimum required pressure head is required in the calculation of these network resilience measures. Difficulties arise when these measures are applied to water transmission systems (WTSs). The reason for this is that in a WTS, water is often pumped into a storage tank or reservoir, in which case the difference between the output pressure head and the minimum required pressure head is always zero. To overcome this shortcoming, it is suggested that the surplus power factor can be used as a network resilience measure because calculation of this measure does not require the pressure value at the outlet of a WDS. In the research presented here, three case studies are used to assess the suitability of the surplus power factor as a network resilience measure for WDSs. A fourth case study is used to demonstrate the application of surplus power factor as a network resilience measure for WTSs, to which the other measures cannot be applied. The results show that the surplus power factor can be used as a network resilience measure to incorporate hydraulic reliability considerations into the optimization of WDSs and particularly WTSs. © 2011 American Society of Civil Engineers.