Numerical analysis of transient regime on high temperature superconductors tapes and current limiting devices

• Grant number: 09/01202-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2009
• End date: March 31, 2010
• Field of knowledge: Engineering - Electrical Engineering - Electrical Materials
• Principal Investigator: Carlos Yujiro Shigue
• Grantee: Renata Pires Ferreira
• Host Institution: Escola de Engenharia de Lorena (EEL). Universidade de São Paulo (USP). Lorena , SP, Brazil

Abstract

Recently a novel generation of high-critical temperature superconductors (HTS) tapes based on the YBa2Cu3O7-d (YBCO) superconducting compound has been developed using a coating process in which texturing is produced during the deposition of the superconductor film on top of buffer layers. The so-called YBCO "coated conductor" (CC) can attain high electric current capacity in a film of 1 micrometer thick. The high performance YBCO CC is aiming at to be the first high scale electrical power commercial application of HTS materials. In spite of its great current-carrying capacity the YBCO CC is prone to degradation when the current is increased above the critical current, Ic due to formation of hot spot located inside the superconducting film. In most applications the possibility of current excursion above Ic has to be considered due to reliability and operational issues. The design of power devices must consider the thermal and electrical conditions wherein a current excursion can occur without damage of the conductor.The aim of this work is the analysis and simulation of electrical and superconducting behavior of tapes and power devices using the YBCO CC during the transition from the superconducting to the normal state induced by current or heat pulse applied in different electric current conditions. The analysis will be done using the finite element method. The coupled constitutive and equilibrium equations have to be considered in order to meet the requirements which describe the transient nonlinear behavior of HTS tapes.The analysis and modelling will be applied to the experimental results obtained from tests of HTS tapes short samples as well as from current-limiting devices under construction in our laboratory.