Um estudo de modelos de máquinas elétricas submetidas a surtos de tensão

• Ano de defesa: 2010
• Autor(a) principal: Alvaro Batista Cancado
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Engenharia Elétrica; Engenharia elétrica
• Link de acesso: http://hdl.handle.net/1843/HPAA-8BGP59

The insulation systems used in the stator windings of electrical machines are not designed, for reasons of space, performance and economics, to withstand high voltage surges resulting from lightning, switching or faults in the power system. Specific standards are used to define the capability of the machines to withstand power surges.Due to its construction relevant differences, multitums coils type windings has a different behavior and supportability of the singleturns bars type windings when they are subjected to high frequency transients. The definition of a standardized modeling that will best represent the behavior of the machine during the high frequency transient phenomena is a complicated task due to the machine constructive complexity. Itswinding distribution is not uniform, with consequent variations in its electrical parameters and therefore its impedance. In this work, some of the high frequency machines models proposed in the literature arepresented and discussed. Field measurements were performed by applying a voltage step at the terminals of the winding of a large hydroelectric synchronous generator, in different configurations. The results are compared with some of the models presented inliterature by means of computer simulations carried out in the ATP program. It was also evaluated some representative models of the machines surge impedances by comparing the values obtained between them to three real machines. It was also conducted laboratory tests and computer simulations to investigate the influence of the physicallocation of protection at the resultant voltage in the machine. It is observed that, depending on the characteristics of the machines and their supply lines, the best positioning of protection with respect to the machine can vary, for a better insulation coordination. We can conclude that some of the models available in the literature represent with goodaccuracy the machines behavior. However, some available models for very fast transients do not offer good accuracy to each other, and require further research to get more accurate results.