Design and Modeling of Superconducting Fault Current Limiter for a High Voltage Substation A Case study: AkAki substation II (400KV to 230KV)
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Date
2017-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Modern electric power systems are becoming more complex in order to meet high load
demand with good quality. So, the increasing amount of on-site generation should be
integrated into the power grid. This translates to more sophisticated electric network with
intrinsically high short circuit current capacity.
A superconducting fault current limiter (SFCL) is proposed as a solution in order to increase
safety margin of circuit breakers (CBs) by reducing the maximum short-circuit current below
the breaking capacity of the substation. SFCL is a device with negligible impedance under
normal operating conditions that immediately switches to a high impedance state in case of
over-current. This advantage makes SFCL a key component in this regard.
At AkAki II substation, 230 kV bus-bar, a hybrid-resistive SFCL is designed. The design
procedure encompasses collection of the substation data, short-circuit analysis of the
substation and designing of all parts of the SFCL. The short-circuit analysis is done using ETAP
simulation software. Then, a hybrid-resistive SFCL is designed to have a current-limitingresistor
with
143.2
MW
rating
at
4.111
kA
and
8.476
Ω,
5.832
cm
width
and
721.76
m
length
of
selected
(Yttrium, bismuth, strontium, copper and oxygen)YBCO coated-conductor, fastswitch
interrupting
9.35
kA
within
48
ms,
and
a
cooling
requiring
80
liters
of
liquid
nitrogen
and
256
kW
condenser.
This designed SFCL is modeled using Matlab/Simulink and the result showed that the SFCL can
minimize the maximum short-circuit current from 44 kA to 35 kA and enables the substation
to clear the fault without problem. This means that the substation can be integrated to
additional power coming from a generation having short-circuit rating of 3585 MVA with the
previous safety margin still.
To implement the SFCL system, the whole system components cost $320,000/phase and
require 10m × 20m area by 1.8m height space of the substation.
Description
Keywords
SFCL design, SFCL model using Matlab, short-circuit analysis using ETAP, AkAki II substation, fault current limiter