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Optimal control of pump rotational speed in filling and emptying a reservoir: minimum energy consumption with fixed time

Research output: Contribution to journalArticleScientificpeer-review


Original languageEnglish
Pages (from-to)1461–1474
Number of pages14
JournalEnergy Efficiency
Issue number6
Early online date12 Mar 2016
Publication statusPublished - Dec 2016
Publication typeA1 Journal article-refereed


An effective way to save energy in pumping systems with low static head is to control the pump’s rotational speed with a variable-speed drive (VSD), which allows changing of the rotational speed when necessary. VSDs can be utilized to control batch transfer systems, for example, in filling or emptying a tank or a reservoir. In the literature, such processes have been optimized only with respect to energy consumption, but the time limit has been ignored. This means that pumping time can be very long. Our paper deals with this optimization problem and considers both pumping time and energy demand, which are often conflicting criteria. We derived a general optimal control law for rotational speed, which can easily be implemented in existing VSDs in the market. Minimum energy and minimum time schemes are special cases of this general new scheme. A constant flow rate scheme, suggested in the literature, is verified to give an optimum solution if the efficiency of the pump remains constant during operation. In addition to energy consumption, rotational speed control can have a favorable effect on the pump’s lifetime, as pointed out in the paper.

ASJC Scopus subject areas


  • Energy efficiency, Process control, Pumps, Variable-speed drives

Publication forum classification

Field of science, Statistics Finland