Analysis of the Effects of Geopolitical Zone - Based Generator Outages on the Performance of the Nigerian 330 kV – 132 kV Transmission Network

Abstract

Power systems are very prone to disturbances and the effect of these
disturbances can be quite severe if the network is not secure. Having an
idea of the effect of some of these unforeseen disturbances will go a long
way in enhancing the system security by putting the necessary mechanisms
in place to avoid such occurrences. This study is therefore aimed at
determining how the line losses and the voltage profile of the Nigerian 330
kV-132 kV transmission system will be affected when the largest
generating stations in each geopolitical zone is knocked out of supply. The
transmission system was modeled in ETAP 19.0 software environment and
power flow analysis was carried out using Newton-Raphson iteration
technique. The generating stations were then divided into their various
geopolitical zones and the highest in each zone knocked off and the power
flow analysis carried out in each case. A comparison of the results
obtained with that of the original network showed that the highest value of
line losses increment of 25% was recorded when Jebba PS, representing
North-Central (NC) zone was knocked. For the voltage profile,
Dandikowa PS outage (representing North-East (NE) zone) led to 31.4%
of the buses violating the voltage limit, which happens to be the highest,
while Jebba PS (NC), Egbi PS (SW), Ihovbor PS/Azura PS (SS), and Alaoji
PS (SE) led to bus voltage violations of 30%, 30%, 14.5% and 13%
respectively as against the 11.8% recorded for the original network. Molai
TS and Yenagoa TS buses recorded the lowest and highest values of bus
voltages in all the cases.