Selection optimization of variable speed pump as turbine (PAT) for energy recovery and pressure management

Abstract

Renewable energy technologies around the world have become a priority today and among them, hydropower plants have the largest share. The most significant problem with small hydropower plants is the high cost of commercial turbines. The most economical way to generate small-scale energy is to use a pump as turbine (PAT) due to the cheapness and availability of the pump. In water distribution networks (WDNs), the PATs can be used instead of pressure reducing valves (PRVs) for both pressure reduction and energy production. The installed PAT must be capable of operating under different discharges due to fluctuations in rate of water consumption, which makes it challenging to select the appropriate pump. In this study, the process of PATs selection for PRVs replacement is optimized using particle swarm optimization (PSO) algorithm. Three different scenarios are performed for the optimization process, considering constant and variable speed PATs. It is worth mentioning that the wasted energy in the selected case study is about 494 kWh/day using PRVs. The results show, in scenario no. 3 (variable speed PATs), the total amount of produced energy is 182.15 kWh/day. Also, the penalty function is decreased by about 62% in comparison to other scenarios and as a result, the pressure of the critical nodes has better agreement to those values of PRVs utilization.