SIMPLE-MODEL FOR POST-FAULT MOTOR BEHAVIOR FOR RELIABILITY POWER QUALITY ASSESSMENT OF INDUSTRIAL-POWER SYSTEMS

Voltage sags are more and more being considered as a severe power qual ity problem. However, stochastic prediction tools for voltage sags are rare. The few methods that have been proposed assume a rectangular vo ltage sag. This assumption is no longer true in many industrial power systems with large induction motor loads. A simple induction motor mod el has been developed to describe the extra current taken by the motor during the re-acceleration after a short circuit. This model has been incorporated in the method for reliability/power quality analysis of power systems, as described in a paper. Simulations are presented to s how the influence of the post-fault voltage sag due to motor re-accele ration on the reliability/power quality of the supply. The simulations result in a table with the expected number of interruptions of plant operation for different load sensitivities.