Research On The Appliication Of Converter Technique In Water Intake Pump Station With Water Level Variation

The water level in some water intake engineering fluctuates with the seasons,or the water level rises by a large extent within a period of abundant rainfall,pumping stations choose the most unfavorable conditions as design basis. However,the pumping station run in little time of the most unfavorable conditions in a year,so the redundant output power of pump waste in valves. To improve the energyefficiency and to prolong the life of the working unit of the pumping stations,variable frequency operation mode should be used, so the characteristics of thevariable frequency pump unit and the characteristics of water intake systems withthe water level fluctuations is necessary to be studied further, and take appropriatecontrol mode.In this paper, the basic characteristics of the water pump and its basiccharacteristics under variable speed operation is studied, with the use ofmathematical fitting method, the basic characteristic curve of the water pump isfitted, and derived the performance curves equations of water pump invariable-speed operation, analyzed the efficiency curve and the high efficiencyinterval. Studied the rules of the efficiency of electric motor and inverter unit withthe variation of frequency, and studied its influence to the total energy consumptionof the water intake system.Due to the practical application need more water pumps work in parallelgenerally, so this paper deduced the performance curve equations of pump inparallel with variable speed operations, and analyzed its operating characteristics. Amathematical calculation model of theoretical energy-saving ratio is established,with the introduction of inverter efficiency and motor efficiency, a comprehensiveenergy-saving ratio calculation mathematical model is established. A case study isfollowed in each model.The actual situation of water intake engineering differ in thousands of ways,the water level ranged variously, the water pumping stations with a small waterlevel range but use variable frequency operation may not have the energy-savingeffect, so this paper discussed the conditions of the use of energy-saving operations, and gives a formula for judging. Finally, according to the requirements ofenergy-saving, an energy-saving control mode is given, by the amplitude of waterlevel variation determines whether the variable speed operation use or not, andgives a control strategy.