Dynamic Analysis of Electromechanical Oscillations in Cascaded Induction Motors Driving Different Loads

This paper presents an investigation of the torsional oscillations occurring in an electromechanical system consisting of two cascaded induction motors connected through mechanical shaft sections to drive different load torques. Matlab Simulink was used as simulation platform to implement the electromechanical system. The electromechanical system equations were implemented in abc reference frame. The dynamic analysis is considering different types of load torques such as constant load torque, load torques increasing linearly with speed, load varying with the speed squared and high inertia load. Results indicate that the torsional stresses are minimized when the system is started against loads vary with the speed and the speed squared. The torsional stresses reaches hazardous values when the system is started against constant load torque condition. The scope of work presents an efficient elimination technique by using variable frequency drives to eliminate the torsional stresses when the system is started against constant load torque condition.