Dissertação
Análise da tensão de restabelecimento transitória em disjuntor de alta tensão: estudo de caso em uma instalação elétrica industrial
Fecha
2021-06-29Autor
Oliveira, Cezar Augusto da Silva
Institución
Resumen
The electrical system is subject to several types of failure occurrences, short circuits and abnormal operating
conditions, thus producing transients in the network. For these reasons, it is essential that circuit breakers
play their role in ensuring the protection and integrity of electrical installations. Thus, they require special
attention in their dimensioning and studies of overcoming by Transient Recovery Voltages (TRVs). The most
common types of faults in electrical installations are short circuits, so the equivalent impedances in the
electrical system undergo changes. As a result, operational risks of circuit breakers already installed and
overrun by TRV increase. In view of all this, there are IEEE STD C37.011-2011 and IEEE STD C37.04b-
2008 standards that are technical guides for the analysis and specification of circuit breakers, establishing
maximum capacities to avoid overruns against TRV. These patterns helped in the understanding and
evaluation of the circuit breaker object of this case study. Thus, this study aims to evaluate the performance
with a focus on TRV of an SF6 gas insulated circuit breaker from a 69 kV substation located in an industrial
electrical installation. Different study scenarios are investigated such as, for example, complete circuit
representing the electrical installations of the substation and simplified electrical circuit of this substation. In
addition, for this TRV analysis, the actual intrinsic capacitance values of the equipment and values
recommended by the IEEE STD C37.011standard were used. Furthermore, changes were caused in the
equivalent impedances of the electrical network and in the voltage level, presupposing a change in
characteristics of the electrical system of the distributor agent. The simulations were performed using
EMTP/ATP and its ATPDraw graphics preprocessor. The results show the need to carry out a detailed TRV
analysis during the development of a substation project, to ensure the proper sizing of the circuit breaker for
a specific application. Another objective of this work was to analytically model the simplified electrical
circuit of the electrical installations of the substation. Therefore, with this mathematical equation a TRV
signal was reproduced, and this signal was compared with the results presented by the ATP/EMTP and PSIM
software. Thus, the work also contributes to the development of analytical modeling presented for TRV
analysis. The result of the TRV signal found through this proposed method was satisfactory and consistent,
thus becoming a tool for comparing the result in this case study.