08-16-2017, 08:48 PM
Increases in the installed capacity and the interconnection of the transmission networks lead to possibility of
fault currents. Fault currents results from various kinds of high voltage stresses caused by lighting and short circuits
or other system disturbances, which send a surge power through the grid.
One of the usages of superconductors is protecting electronic devices and systems from short circuit [1].
There are three types of superconductors fault current limiters (SFCL): resistive, inductive and hybrid. Protection of
scheme from current overload by resistive SFCL is based on nonlinear current-voltage characteristic of the
superconductor. When current density exceeds some critical value, superconductor come to normal state and its
electrical resistance rapidly increases.
In order to design SFCL for practical applications, knowledge of SFCL parameters such as maximum load,
response time and thermal recovery time is essential [2]. On the other hand, the electromagnetic and thermal
response of a SFCL to a fault involves very high voltages and currents at very short times, and therefore there is a
formidable challenge for experiments. Computer simulations are obviously helpful, since they allow to research on
arbitrary time scales and power levels. Modelling and analysis of superconducting fault current limiter include
simulation of thermo- and electrical behaviour. Thermal properties deal with resistive heating caused by current
losses, increasing resistance etc. Electrical conductivity nonlinearly depends on temperature and current density.
Thus, simulation of SFCL is complicated due to interdependence of thermal and electrical properties, and nonlinear
dependence of electrical characteristics from temperature and current density. Many models of superconductor fault
current limiter were implemented and evaluated [ 3, 4, 5]. But there are still unsolved problem of integration these
models to existing CAD systems.
In this paper we present a simulation of the resistive SFCL behaviour with Matlab/Femlab/Simulink
environment. Mathematical model built in Femlab can be easily integrated with existing designing systems built
with Matlab/Simulink.