Pressure and Energy Management in Water Distribution Networks through Optimal Use of Pump-As-Turbines along with Pressure-Reducing Valves
Milad Latifi, Kambiz Farahi Moghadam, Seyed Taghi Omid Naeeni
Abstract
Occurrence of high pressure in water distribution networks (WDNs) may generally result in leakage, bursting, and overconsumption. Temporal and spatial variations in pressure values cause dissatisfaction of consumers and distrust of WDNs. Pressure management is an operational strategy to improve the reliability of WDNs. This strategy should be considered as a cost-savings practice due to the fact that operating costs are a significant proportion of WDN costs. In the present study, the surplus pressure in a WDN, consumed by turbines, is used to generate energy and compensate for some of the costs. Due to the high cost and specialized construction of the turbines, the pumps working in reverse or pump-as-turbines (PATs) have been employed in the WDNs instead of turbines. This investigation aims to improve the network performance by installing PATs with the appropriate number, type, and time schedule in the right locations. In this regard, the optimal schedules for pumping and using pressure-reducing valves (PRVs) have been considered. A numerical model was developed to optimize consumers’ satisfaction and costs as objective functions. The efficiency of the proposed model was evaluated by selecting a case study with overpressure, and additionally, the objective functions were optimized by using two scenarios. The results associated with the first scenario indicated a reduction of network costs by up to 90% over its life cycle as well as an increase in network reliability. Through the second scenario, multiobjective optimization provided a trade-off diagram as the final solution for choosing various solutions with different cost levels and reliabilities.