4 - Kuwait Oil Company

The simulation results of the scalar control – V/F open loop drive, are shown in the followingfigures:Figure.1: Load torqueFigure 2: Load speedFigure 3: V/F ratioThe above figures show the implementation of open-loopconstant V/Hz control of an induction machine.The open-loop constant V/Hz operation is simulated forFigure 4: Variable output load speed1.2s ramping up and down the speed command (as shownin figure No. 2 in 1.5, 3.5 & 4.5 seconds) and applying stepload torques (as shown in figure No. 2 in 8 & 10 seconds).Figure No. 3 shows the change in V/F ration when changingthe speed command while maintaining a constant ration toavoid flux saturation.Figure No. 4 shows the performance of motor speed whenchanging the required speed and time required to approachthe desired speed. We can notice that there is some delay.However, this delay & performance has been improved byimplementing other controller technologies such as Field-Oriented Control (FOC) and Direct Torque Control (DTC).At Kuwait Oil Company, variable speed drives will continueto be used widely in production, gas and export facilitiesto reduce power consumption and create better efficiencyand control over operations. In addition, as technologiesimprove, the Company will play a major role in adoptingnew and improved methods to help better create a moreefficient and productive environment.22October - December 2012