Modeling Variable Speed Pumps for Optimal Pump Scheduling

Conference paper (2016)

Authors

Ruben Menke Imperial College London
E. Abraham Imperial College London
Ivan Stoianov Imperial College London
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Published Date

2016

Language

English

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Abstract

Increasingly more variable speed drive pumps are installed in water distribution systems worldwide. However, the modeling of variable speed drives in such networks remains difficult, especially in the context of mathematical optimization for pump scheduling. For the problem of energy usage minimization, formulated as a mixed integer program, we propose a new simplified convex relaxation of the hydraulic characteristics of a variable speed pump. By using different model approximations for the power curve, as a function of pump speed and volumetric flow rate, we study the trade-off in the computational complexity and quality of solutions obtained. We use two small benchmark networks and real pump data from three different pumps to calculate operating schedules. We show that these schedules, are computed in a time suitable for operational usage, enable operation with lower operating cost compared to fixed speed pumps, and their sub-optimality can be computed.