Fuzzy Method Applied at Energetic and Economic Rehabilitation of Pumping Station

Many pumping stations require an urgent rehabilitation from hydraulic, energetic, and economic point of view, being older than 30 years. Some urban stations for the water supply are nowadays under-dimensioned compared with the necessary consumption. Such an example is the pumping station of the Buzau City, realized in 1986. Its population has grown in the last decades by about 30% due to industrial development and its water pumping station from the treatment plant is currently totally insufficient. The hydraulic losses through the control discharge valve have become too high. This pumping station ensures the water supply for the south and east part of the city. Firstly, some characteristics of the pumping station equipped with pumps 12NDS- Normal-Double spiral casing-Single-layer of 160kW and 18NDS of 400kW and 500 kW, all from domestic production, are presented. Modernization of the pumping station has started few years ago and being realized in steps, so as not interrupt the city’s water supply. To establish the optimal operating point some algorithms are presented, developed based on the experimental data and using functions with one or two independent variables. Firstly, the interpolation function is determined, followed by its numerical calculation. To establish the characteristics’ equations H = f(Q), P = f(Q), and η = f(Q) starting from experimental results obtained by direct measurements, a polynomial approximation was chosen by the method of the least squares, using the polynomials Lagrange and Bezier. For optimization, the fuzzy technique is adopted regarding the flow fusing, intervals between start and stop following some policies concerning the aggregates’ starting. For a year, the energy saved between these intervals was calculated. Finally, the obtained yields of about 90% proved that the pumps modernization adopting new functioning techniques is more advantageous in some situations than the purchase of new equipment.