Avaliação da degradação de semicondutores de potência com o uso contínuo em compensadores estáticos

Abstract

Nowadays the Static VAr Compensators is a equipment essentially important for the electric power system. The rapid development technologic has offered the Static VAr Compensators (SVC) as solution to a number of problems encountered in electric power system. However, research in degradation of semiconductors applied in SVC is still developing. The objective of this dissertation is to introduce a methodology for diagnosing semiconductors degradation, applied in SVC type Thyristor Switched Capacitor (TSC) and Thyristor Controlled Reactor (TCR), resulting in the improvement of operational performance of SCV. It also presents the results of tests carried out in semiconductors during different stages of degradation, and how the junction temperature affects the semiconductor blocking capability. In Chapter 1, general comments are made on the importance of the SVC in electric power systems and the research development on semiconductors degradation, especially in the context of actual Brazilian Electric Model. In Chapter 2, there are some comments about the benefices of SVC´s application. Following this, in Chapter 3, the main types of SVC are presented, and the basic configuration of the SVC researched. Avaliação da Degradação de Semicondutores de Potência Com o Uso Contínuo em Compensadores Estáticos Universidade ederal de Itajubá x Next, in Chapter 4, a performance analysis of SVC in service in national grid of Brazil is done, emphasizing failure rates of semiconductors e availability rates of SVC. In Chapter 5, a brief review of semiconductors theory is provided, considering the electrical characteristics of thyristors and diodes. It Chapter 6, the failures of semiconductors are analyzed and classified according to the characteristics of damage. Following this, in Chapter 7, the concept of various levels of degradation (normal, defect and failure) is introduced. It is presented which parameters of semiconductors shall be analyzed to determinate the level of degradation. In Chapter 8, the results of tests carried out in semiconductors during different stages of degradation are discussed, highlighting the analysis of voltage-current characteristics, and the behavior of the leaking current when the maximum ratings of repetitive peak off-state voltage and repetitive peak reverse voltage are applied. The manner in which junction temperature affects the semiconductor blocking capability is also presented. Finally, in Chapter 9, conclusions are drawn. Some recommendations are given, including proposals for developing of new research projects.