An optimal control strategy based on virtual flow measuring for variable flow primary pumping

A virtual flow measuring is integrated with the best efficiency staging and the loop differential pressure (DP) reset method to unleash pump power saving potentials from a variable flow primary pump system. Based on the measured pump head, speed, and power, the virtual measuring determines the pump operation condition in an accurate and fast way. The pump operation parameters are then used to realize the best efficiency staging and the loop DP reset control, which calculate the optimal number of operating pumps and each pump's speed respectively. Simulation shows that this control strategy is most energy efficient, and it saves on pump energy consumption by 74.8% compared with a constant flow pumping system. The experiment from a retrofitted two-pump system also shows that the control strategy provided 64.5% pump energy saving over the original constant flow system. In addition, this control strategy requires a lower initial cost, simplifies the implementation process, makes system operation more reliable and stable, and reduces maintenance demands.