Study of operational modes of an "electric drive–turbomachinery–pipeline" technological complex

Abstract

A developed mathematical model of an asynchronous motor – turbomachinery pipeline technological complex is presented. An analysis of starting conditions is carried out by a nonlinear differential calculus and graphic analytical method. The calculations for the model were performed using the MATLAB software package. The flow, head, efficiency of the pump mechanism and entire pump unit, stator current, angular frequency and torque of the asynchronous motor were calculated at pump start-up and with an increase of pipeline resistance coefficient by 2, 5, 10, and 1000 times. At an increase in the pipeline resistance coefficient by 10 times, the pump efficiency is shown to be reduced by 2.8 times, while the head is increased by 1.28 times; meanwhile, the torque, stator current, and rotational speed of the asynchronous motor change insignificantly. The torque and current decrease by 1.167 and 1.034 times, respectively, while the speed increases by 1.0046 times; the efficiency of the pump mechanism and pump assembly (including motor) decreases by 1.78 and 1.89 times, respectively. The start-up time of the pump motor equals 0.5 s; the maximum stator current at start-up exceeds the nominal value by 4.39 times; the steady-state stator current comprises no more than 59.3 % of the nominal value. The developed mathematical model of the asynchronous motor – turbomachinery – pipeline technological complex is established to allow the operational and energy parameters of the unit to be quantitatively estimated at start-up, while the pump capacity is capable of being controlled by throttling.