| 摘要 |
PROBLEM TO BE SOLVED: To properly obtain a stage increase point and a stage decrease point, to exactly decide the number of operation units, and to decide the stage increase point and the stage decease point by taking into consideration actual operation states of pumps, when determining a stage increase and a stage decrease of the number of the pump operation units.SOLUTION: A control device 8B obtains the power consumption Wp of secondary pumps 6A to 6C from a formula (11), and decides, as an optimum operation unit number Nop, an operation unit number time including the fact that the pump power consumption Wp becomes minimum as a condition. In detail, the control device 8B obtains the pump power consumption Wp with respect to a present operation unit number time of each secondary pump 6A to 6B, a one-unit increase time increased by one unit from a present operation unit number, and a one-unit decrease time decreased by one unit from the present operation unit number, respectively, obtains a pump operation frequency fs from a formula (7), and decides, as the optimum operation unit number Nop, the operation unit number time which satisfies a condition 1: the pump operation frequency fs is equal to or lower than a pump maximum frequency fmax, and a condition 2: the pump power consumption Wp is minimum. |
