Verificação do efeito de cabos longos no acionamento de motores elétricos.

Abstract

This study addresses a widely debated issue in the oil eld nowadays. The control and drive of high power submersible centrifugal pumps is very complex and nowadays there are few experts researching in the area. That was the great incentive of choice of topic. The work is to verify the e ects on the alternating voltage signal generated by an inverter into the terminal of an engine when it goes a very long feeder. At the beginning we have a basic approach on inverters and their topologies as well as some techniques used to perform the switching of the same. We discuss some problems in using a simple inverter with three levels and what are the advantages of using a multilevel inverter in the problem at hand. Soon after we discussed the distortions caused by long cables. We have the skin e ect which actually is not the great agent of the results and in particular the e ect of re ection of traveling waves which represents much of the distortion of the transmitted signal. Then, we discuss a mathematical model of a long cable to allow the simulation of the system. As there is no model today for such a situation, we took part of the transmission lines theory that is very similar to the problem at hand. Finally, we have the full system simulation using matlab simulink tool. The system consists of a three-phase nine level PWM inverter connected to chosen long cable model that connects to a three-phase induction motor. After the simulation, several graphs were generated so that we can visualize and analyze the results. Keywords: submersible centrifugal pumps, inverters, multilevel inverters, PWM, skin e ect, wave re ection, long cable, induction motor.