Method for controlling pumping of pump units in a wet well

Abstract

A method for controlling pumping of a plurality of pump units in a wet well is disclosed. The method uses a genetic algorithm to determine which of the pump units is to be started and its initial operating frequency when the liquid level in the wet well reaches a first predetermined level for pumping. During the pumping process, the pumping control method monitors the liquid level in the wet well in real time to obtain real-time state information and fine-adjusts the initial operating frequency of the pump unit to be started according to the real-time state information. Therefore, the present disclosure achieves optimum efficiency and energy saving.

What is claimed is: 
     
         1 . A method for controlling pumping of a plurality of pump units in a wet well, comprising the steps of:
 (1) monitoring inflow of the wet well;   (2) when a liquid level in the wet well reaches a first predetermined level for pumping, calculating an objective through an algorithm according to pumping performances of the pump units and the inflow so as to determine one of the pump units to be started and an initial operating frequency thereof and to generate an initial control signal;   (3) sending the initial control signal to the one of the pump units to be started, and setting the initial operating frequency to the one of the pump units to be started for pumping;   (4) monitoring the liquid level in the wet well in real time to obtain real-time state information;   (5) determining whether a fine adjustment condition is met according to the real-time state information, wherein when the fine adjustment condition is met, the initial operating frequency for the one of the pump units to be started is fine-adjusted and the step (4) is performed, and when the fine adjustment condition is not met, the step (6) is performed; and   (6) determining whether the liquid level in the wet well reaches a second predefined level for stopping pumping, wherein when the liquid level in the wet well reaches the second predefined level, the pump units are stopped, and when the liquid level in the wet well does not reach the second predefined level, the step (4) is performed.   
     
     
         2 . The method of  claim 1 , wherein the algorithm is a genetic algorithm. 
     
     
         3 . The method of  claim 2 , wherein the pumping performances of the pump units comprise pumping capacities and energy consumptions assessed through performance curves of the pump units and pipeline system curves of a pumping station, and the objective is a minimum total energy consumption of the pump units. 
     
     
         4 . The method of  claim 3 , wherein the genetic algorithm comprises an operation based on a condition that a total of the pumping capacities of the pump units is equal to the inflow of the wet well. 
     
     
         5 . The method of  claim 1 , wherein the real-time state information is a liquid level difference in a unit time. 
     
     
         6 . The method of  claim 5 , wherein when the liquid level difference in the unit time is less than a minimum allowable value, the fine adjustment condition is not met. 
     
     
         7 . The method of  claim 5 , wherein when the liquid level difference in the unit time is less than zero, the fine adjustment condition is met, and the initial operating frequency for the one of the pump units to be started is fine-adjusted downward but greater than or equal to a minimum safety frequency. 
     
     
         8 . The method of  claim 5 , wherein when the liquid level difference in the unit time is greater than a limit value, the fine adjustment condition is met, and the initial operating frequency for the one of the pump units to be started is fine-adjusted upward. 
     
     
         9 . The method of  claim 1 ., wherein the step (3) further comprises determining whether the one of the pump units to be started is already started, wherein when the one of the pump units to be started is already started, the initial operating frequency for the one of the pump units is set to the one of the pump units to be started, and when the one of the pump units to be started is not started, the one of the pump units to be started is started first and then the operating frequency is set to the one of the pump units to be started.