Abstract:
The overall electricity access rate is still very low in most sub-Saharan African (SSA)
countries. The rate is even lower in rural areas where most of the population in these
countries live. One of the main obstacles to rural electri cation (RE) is the high cost
of laying the distribution infrastructure owing to the dispersed nature of loads and
low demand. Thus, electrifying the rural areas needs to be considered holistically
and not just on the nancial viability. To reduce cost, it is important that auxil-
iary service voltage transformer (ASVT), which are cheaper than the conventional
substation be explored. ASVT have been tried successfully in some parts of the
world like Congo and Mexico. However the literature review showed that no work
had so far been done with regard to determination of the penetration point and
maximum penetration level of these technologies on power transmission networks.
These ASVT sub-stations have the ability to tap power directly from high voltage
transmission lines of either 132kV or 220kV and step it down to 240V for single
phase distribution.
This research investigated the penetration point and maximum penetration level of
ASVT sub-stations in power transmission networks with regard to transmission line
voltage pro le.
The research was done by simulating ASVT sub-station models terminated in High
Voltage transmission lines using SIMULINK software. The realized voltage levels
were compared with the expected H.V transmission line voltage levels to determine
whether the voltage pro le had been violated. The ASVT loadability curves and the
constructed Surge Impedance Loading (SIL) curves were used to ascertain voltage
stability of the system. The research revealed that the rst ASVT sub-station can
be terminated at any point on the H.V transmission line without violating voltage
pro le.
The simulation further revealed that a maximum of nine ASVT sub-stations can
be terminated on a 440km, 132kV transmission line without violating the voltage
pro le of the transmission network.
