Selection of Pumps as Turbines Substituting Pressure Reducing Valves

Technical standards define operational limits for hydraulic parameters such as velocity or pressure. On this way, pressure control is a fundamental component for safe operation at water supply systems, mainly to reduce leakage, risk of disruptions and maintenance costs. The system topology and topography can define some high pressure zones and in this case the use of Pressure Reducing Valves - PRV - to maintain standards pressures on the sector is common. However, all the energy available on the fluid is dissipated trough headloss. A turbine could be used instead of the PRV to produce electrical energy and to control pressure. In general, the power available in these sites is under 100 kW, so the use of Pumps as Turbines - PAT - is recommended to reduce the investment. Due of the dynamic operation trough a day, the PAT will operate under different conditions of flow and head. This variation will affect its efficiency and head loss, which difficult the selection trough conventional methods. Therefore, this paper proposes a method for PAT selection to operate instead a PRV. The method is based in the maximization of the energy produced, constrained to the pressure limits on each node of the network. To solve this problem, the optimization technique PSO is used and the available curves in literature, on the Suter plane, are used to simulate the PAT. The method is applied on a network and the results are compared with the PRV operation.