Speed optimization control of parallel-connected variable speed pumps

Regarding the problem of speed optimization control of parallel-connected variable speed pumps (VSPs) in close loop water circulating system, develops a characteristic model of the VSPs. It is proved that the similarity of working condition (SWC) of each pump would not change when the speed of the parallel-connected VSPs is adjusted proportionally. Derives the analytical expression of the characteristic value for the working condition of pumps, which implies that the overall efficiency of parallel-connected VSPs is the highest when all the parallel-connected VSPs keep the same characteristic value of working condition during the regulating process. Based on this, derives the analytical expression for the optimal speed ratio of parallel-connected VSPs. Summarizes three criteria for speed optimization control of parallel-connected variable speed pumps.