Energy Consumption of Variable Speed Pumps Under Transient-State Condition in Water Distribution Networks

This article aims at drawing a comparison between the power consumption and cost incurred for variable speed pumps (VSPs) working under steady-state and transient-state conditions in a water distribution network. A 24-h variable water demand pattern was attached to a residential community water distribution network in EPANet 2.2 for simulation along with introducing a pipe leak at a critical node to assimilate the transient-state condition. It was observed that there was a significant difference in the energy consumption of VSPs working at lower and high speeds when compared with their nominal speed. The results show an energy cost cut of 40% at 15% lower speed and an energy cost hike of 50% at a 15% higher speed of VSP than its nominal speed. A mathematical relation is developed to estimate the energy cost difference at any speed of VSP working under the transient-state condition in a water distribution network.