Energy Efficient Operation of Variable Speed Submersible Pumps: Simulation of a Ground Water Well Field

Due to their lower energy consumption, permanent magnet synchronous motor (PMSM) submersible pumps have been introduced in ground water well field operation. Besides direct savings of energy, the introduction of PMSM pumps together with the required variable frequency converters offers new operational scenarios to meet the seasonally varying water demand. In this work, potential energy savings of variable speed submersible pumps were investigated. A ground water well field consisting of 13 wells and their transport pipes was modeled in the hydraulic modeling software EPANET 2.0. Using MS visual basic for applications, EPANET was coupled with MS Excel and a genetic algorithm to identify the most energy efficient combination of pump speeds. For the simulated well field, the total specific energy demand required for pumping was significantly lower in partial load operation as compared to nominal pump speed operation. For low and moderate flow scenarios, energy savings in the range of 20% compared to nominal speed operation can be achieved. These findings were confirmed by a monitoring campaign in the well field. Combining hydraulic simulation and optimization using genetic algorithms, the best efficiency scenario for operation of ground water well fields can be found.