Prof.
Omoigui M.1, Lawal O.A.2 & Alao R. A.3
1DepartmentElectrical and Electronic, Obafemi Awolowo University, Ile-Ife
2Department Electrical
and Electronic, University of Ibadan, Ibadan, Nigeria
3DepartmentElectrical and Electronic, University of Ilorin, Ilorin, Nigeria
Corresponding
Author: Lawal O.A
ABSTRACT
The Nigeria 330kV network has been
presented in this research work. The network just like many power systems in
the world suffer from voltage instability caused by the variation in the
reactive power requirement of the systems’ components. This has a resulting
effect on consumers’ loads designed to operate within a specific voltage range.
The system voltage goes high when there is excessive injection of reactive
power and goes low when there is excessive absorption of reactive power. Ten (10) generating station buses and
twenty-two (22) transmission line buses totalling thirty-two (32) buses were
considered. Load flow solution was performed on the buses using Newton-Raphson
method. This was programmed in matlab and the voltage magnitudes of all the
buses were determined. The steady state voltage stability was investigated and
the problem buses were identified. These were bus 16 (Yola), bus 23 (Alaoji), bus
26 (Gombe) and bus 30 (Ugwuaji). The voltage magnitude of bus 16 (Yola), bus 26
(Gombe) and bus 30 (Ugwuaji) are higher than what is specified in the Operating
Procedure of the National Control Centre while that of bus 23 (Alaoji) is lower
than the statutory limit specified. The Static VAr Compensation scheme deployed
did not allow a noticeable voltage drop or voltage increase beyond the
statutory limit. The scheme was used in this research to supply reactive power
to boost the power system voltage magnitude on any of the problem buses and
absorb reactive power to reduce the voltage on any of the buses. The
compensation scheme reduced the voltage magnitudes of bus 16 (Yola), bus 26
(Gombe) and bus 30 (Ugwuaji) from 1.137pu to 0.975pu, 1.131 to 0.986pu and
1.055pu to 0.987pu respectively. The reactive power compensation scheme was
also applied to bus 23 (Alaoji) to increase its voltage magnitude from 0.832pu
to 0.954pu. Other buses that were affected positively are bus 10 (Kaduna) from
1.049 pu to 1.000 pu, bus 13 (Kano) from 1.042 pu to 0.992 pu, bus 14 ( Jos)
from 1.052 pu to 0.993 pu, bus 15 (Makurdi) 1.051pu to 0.992pu, bus 18 (Benin)
from 1.026pu to 1.027pu, bus 19 (Onitsha) from 0.978 to 0.984, bus 22 (New
Haven) from 0.975pu to 0.981pu. The
transmission line active power losses in the network were also determined
before and after the compensation were applied. These two values were compared
to get the increase in transmission efficiency due to the compensation. The
compensation brought about a 17.48 percent increase in efficiency. The Static
VAr Compensation scheme in this research has been shown to be an efficient tool
in maintaining short and long term voltage stability so as to reduce overall
transmission losses in the Power System Network. In order to ensure a cost
effective optimal load flow, Genetic Algorithm was employed to reduce the cost
of electricity generation by the generating power stations. These allotted the
generating stations with appropriate capacity to meet the load demand while
reducing the cost. This further improved the voltage stability of the network.
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