Short Circuit Analysis of a Nigerian 132/33 kV Injection Substation

Abstract

Every power system, in addition to meeting the present load demand
should also be flexible enough to meet, on a continuous basis, the
future demands. As a result of this continuous increase in demand,
there is the tendency of failures occurring in power systems. Hence
there is the need for adequate analyses like short circuit analysis, etc
to be carried out so as to have a good protection system. This study
is aimed at carrying out short circuit analysis in an injection
substation so as to enable adequate protective system to be
incorporated. The study was carried out in the 50 MVA 132/33 kV
Ado-Ekiti injection substation situated in Ado-Ekiti, Ekiti State,
Nigeria. The network was modeled in the ETAP 16.0 environment and
then load flow analysis was carried out using Newton-Raphson
iteration technique. The load flow analysis was carried out on the
original network before short circuit fault was then introduced
separately in one bus each in the 132 kV and 33 kV part of the network
with the load flow analysis repeated in each case. It was discovered
from the study that after the short circuit fault was introduced, the
voltages in the faulted buses reduced to 0 A in each case while the
currents flowing from the faulted buses increased drastically. The
highest current registered was 3138 A, which was flowing from bus
18 when the short circuit current was introduced in that bus as
against 722 A which was flowing from bus 1 when the fault was
introduced at bus 1. It was also observed that the fault at bus 18, from
which 3 feeders (Ado, Iworoko and Ilawe feeders) radiated had a
greater impact on the network and as such, efforts should be put in
place to avoid such a scenario.