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Since independence, Nigeria has never known constant power supply and smooth distribution of power. Power demand is of paramount interest to the electrical engineer concerned with the generation, transmission, and economic implications of electric energy. This situation is so due to the technical and economic implications of electric energy production/consumption. Benin City as one of the load infested areas in Nigeria could provide a solution to the problem of stabilizing power supply in Nigeria if carefully studied. This study reveals that the power demand in Benin Cit y has been on the increase. This is an eye opener to the PHCN (Power Holding Company of Nigeria), which must take appropriate measures necessary to accommodate this increasing power demand. The study further reveals that the Brewery factory in Guinness injection substation has the highest load density with a
value of 102.0 VA/m2 this is due to the running of motors for 24/7 hours. The lowest
load density is that from the Dam feeder in Ikpoba Dam., with a value of 0.3VA/m2.
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Electrical energy demand in Nigeria is on the increase due to the ever increasing population and the attendant increase in commercial and industrial activities. This is even worse in urban centres where the population is concentrated due to rural to urban drift in populations. [Michael, 1972]
As power demand grows with population growth the generation, transmission and distribution networks must be strengthened to cope with the consequent technical and economic shortfalls. With increasing power demand, the loading of the generators, transformer, transmission lines and all the associated switchgear also increase. Hence, concerted efforts must be made to monitor the pattern of this power demand so that appropriate financial and technical measures can be taken to enhance the status of the power distribution/transmission network equipment..
A load survey of this nature is necessary because, with increasing demand for power all the distribution network equipment will have to handle larger normal and fault current levels, hence complexity and cost of protective gear required will also increase. [Theraja, 1995]
This study will help the power utility engineers to plan for and forecast future trends in power demand, and thus be able to take appropriate techno-economic measures necessary to forestall power outages. This will make for a stable power supply and improve the standard of living of the citizenry (consumers). A network diagram for Benin City is shown in Fig 1.0
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This study being rather a load survey is a statistical problem. In this case injection sub-stations in Benin Cit y with their distribution transformers were surveyed, in order to achieve a good estimate of power demand, the KVA rating and KVA readings for every one hour for one week were taken and recorded. Some consumer loads were also measured and recorded.
Certain performance factors such as average demand, maximum demand
factor, diversity factor, load factor, load density and coverage area, were investigated
in this study, where Average Load | = | Kwh consumed during the period considered |
Hours in the period considered | ||
Demand Factor | = | Maximum demand (usually < 1) Total Connected Load |
Diversity Factor | = | sum of individual maximum demand Maximum demand of the entire load |
Load Factor | = | Average power per year (or per month or per day |
Maximum demand
Load Density = Capacity of transformer in KvA Area Covered by transformer in m2
= Load
Area Covered by Load
The various classes of consumers surveyed include the residential consumers, commercial and industrial consumers. The seven injection substations selected for the purpose of this study are Etete, Nekpenekpen, Ugbowo, Ikpoba dam, Guinness, Siluko and GRA injection substation, the rated powered and voltage ratios of transformers, and load reading were taken
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s/no | Name of Injection substation | Rated Power | Rated Voltage Ratio of Transformer |
1 | Etete | 20.5MW | 33/11KV |
2 | Nekpenekpen | 13.5MW | 33/6.6KV |
3 | Ugbowo | 13.5MW | 33/6.6KV |
4 | Ikpoba Dam | 6.6MW | 33/11KV |
5 | Guinness | 12.3MW | 33/11KV |
6 | Siluko | 20.5MW | 33/11KV |
7 | GRA | 13.5MW | 33/11KV |
S/no | Name of Injection Substation | Rated Capacity |
1 | Etete | 22.5MVA |
2 | Nekpenekpen | 15MVA |
3 | Ugbowo | 15MVA |
4 | Ikpoba Dam | 7.5MVA |
5 | Guinness | 15MVA |
6 | Siluko | 22.5MVA |
7 | GRA | 15MVA |
Name of Injection Substation | Names of Feeders |
Etete A | Sapele road A1, Ihama Road A2, Ugbor A3 Dumez Road A4 |
Nekpenekpen B | Feeder 1, B1, Feeder 2, B2, Feeder 3, B3, Feeder 4, B4 |
Ugbowo C | Federal Girls Road, C1 Uselu Road, c2 Edaike C3 Ugbowo, c4 |
Ikpoba Dam D | Okoro Road, D1, Uselu Road D2, Edaike D3, Dam D4 |
Guinness E | Brewery E1, New Benin E2, Auchi Road E3 Asaba Road E4 |
Siluko F | Uwelu Road F1, Edo Textile F2, Oliha F3, Upper Siloko Road F4 |
GRA G | Palace G1, Sapele Road G2, GRA G3, Reservation G4 |
The total individual load in KVA and the coverage area in m2 of each injection substation were estimated and tabulated as shown in table 4, the coverage area being
the space of land inhabited by consumers.
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s/no | Injection substation | Feeders | Load (KVA) | Area (m2) (space of land covered by consumers | Total load | Total Area (m2) |
1 | Etete | Sapele road Ihama road Ugbor road dumez road | 7300 13315 700 1200 | 86180 453440 578730 62500 | 38.815 | 1180850 |
2 | Nekpenekpen | Feeder 1 Feeder 2 Feeder 3 Feeder 4 | 5400 7900 9750 3600 | 2654060 9433610 6823410 28887080 | 26.650 | 51279040 |
3 | Ugbowo | Okhoro road Upper lawani Dam | 2300 2300 900 | 73540 10506320 38899780 1708940 | 13.600 | 42454100 |
4 | Guinness | Brewery New Benin Auchi Road Asaba road | 7500 57600 2650 7115 | 459900 1046710 1551690 358780 | 23.025 | 161178580 |
5 | Siluko | Uwelu road Edo textile Upper Siluko Oliha | 1900 7000 4100 7900 | 1667370 231000 5888610 3477900 | 20.900 | 6646140 |
6 | Gra | Palace Sapele GRA Reservation | 7650 800 9000 7400 | 24.850 | 11265080 |
From table 4, the individual load density can be determined for each feeder. Considering, for example the Sapele Road feeder in Etete injection substation, we have:
Total load = 7300 KVA Total area = 86180m2
Therefore load density = load/Area Covered by load = 7300 KVA/86180m2 = 0.0847
KVA/m2 = 84.7VA/m2
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Repeating the above procedure for all the feeders in table 4 result in table 5 shown blows with an additional column for load density in KVA/m2
Injection substation | Feeder | Total Load (KVA) | Coverage Area (m2) | Load Density (KVA/m2) |
Etete | Sapele Road Ihama Road Ugbor Road Dumez Road | 7300 13313 6700 1200 | 86180 453440 578730 62500 | 0.0847 0.0294 0.0168 0.0192 |
Nekpenekpe | Feeder 1 Feeder 2 Feeder 3 Feeder 4 | 5400 7800 9750 3600 | 6254060 6326670 40359200 1939110 | 0.0020 0.00012 0.0002 0.00019 |
Ugbowo | Federal Girl Road Uselu Road Egua Edaken Ugbowo | 2900 5400 2500 8400 | 4469060 6326670 40359200 1939110 | 0.0006 0.0007 0.00016 0.0004 |
Ikpoba Dam | Okhoro Road Upper Lawani Dam | 2300 2300 9000 | 6743610 6823410 28887080 | 0.0003 0.0007 0.0003 |
Guinness | Brewery New Benin Auchi Road Asaba Road | 7500 5760 2650 7115 | 73540 10506320 3889780 1150450 | 0.1020 0.0005 0.0007 0.00062 |
Siluko | Uwelu Road Edo Textile Upper Siluko Road Oliha | 1900 7000 4100 7900 | 459900 104710 1488690 358754 | 0.00041 0.0067 0.0022 0.0028 |
GRA | Palace Sapele GRA Reservation | 7600 800 9000 7400 | 1687570 231060 5888610 3477900 | 0.0045 0.0035 0.0015 0.0021 |
Daily Observation of maximum KVA Power demand was carried for 21 Consecutive days at each of the injection substations and the result were recorded as shown in
table 6
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From table 6, the load and demand factors can be calculated for each injection substation as follows:
For Etete injection substation: Day 1
Total KVA m. d = 9248 KVA
Average demand = 9248/42 = 389.5 KVA Maximum demand per 30 minutes = 510 KVA Total connected load = 38815 KVA
Load factor = Average demand/Maximum demand = 38915 / 510 = 0.7637 = 76.4% Demand factor = Maximum demand / Total connected load = 510 / 38815 = 0.01321
= 1.31%
The same procedure is repeated for other injection substations.
The Brewery injection substation feeder has the highest load density of 0.102
KVA/m2 and the dam feeder at Ikpoba dam injection substation, the lowest at
0.003 KVA/m2. The heavy industrial and commercial activities around the brewery area could have motivated PHCN to supply more of its available power to this area, considering the enormous financial returns on invested capital.
(a) There should be a map showing the connectivity of the houses in the various substations in Benin metropolis
(b) Any new house connected to the grid should be recorded for effective tariffs
(c) Records of Updated appliance in use by consumers should be sent to PHCN to enable them upgrade the various substations.
(d) To enable corrective repairs, all tariffs should be paid promptly
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(e) Proper computerization should be encouraged.
Cogdell J.R. (1990) Foundation of Electrical engineering; Prentice Hall, Inc Michael N. (1972) Electrical Installation Technology, 1st edition McGraw Hill Publishers New York.
Paddlock J. O. And Garvin R. A. (1982) Electrical Installation Technology and
Practice 13th edition Macmillan Ltd; London
Theraja B. J. ; (1995) Electrical Technology, 2Nd edition, schad and co. New Delhi
Pp1002 – 1015
Uppal S. L. (1998) Electrical Power, 13th edition Khanna Publishers New Delhi
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S/N | Injection Substation | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 | Day 8 | Day 9 | Day 10 | Day 11 | Day 12 | Day 13 | Day 14 | Day 15 | Day 16 | Day 17 | Day 18 | Day 19 | Day 20 | Day 21 |
1. | ETETE | 510 | 480 | 520 | 516 | 576 | 560 | 540 | 520 | 514 | 490 | 510 | 550 | 520 | 522 | 515 | 510 | 485 | 520 | 550 | 510 | 515 |
2. | NEKPENEKPEN | 400 | 390 | 400 | 410 | 450 | 440 | 440 | 420 | 400 | 410 | 420 | 452 | 420 | 405 | 450 | 410 | 440 | 425 | 440 | 450 | 440 |
3. | UGBOWO | 410 | 410 | 410 | 420 | 440 | 430 | 420 | 410 | 420 | 410 | 410 | 430 | 430 | 440 | 420 | 420 | 410 | 420 | 440 | 430 | 420 |
4 | IKPOBA DAM | 550 | 460 | 500 | 492 | 504 | 570 | 480 | 500 | 460 | 480 | 520 | 520 | 500 | 500 | 480 | 550 | 560 | 490 | 504 | 500 | 480 |
5. | GUINESS | 440 | 464 | 480 | 480 | 540 | 520 | 520 | 520 | 510 | 480 | 480 | 540 | 430 | 440 | 460 | 480 | 520 | 510 | 500 | 540 | 500 |
6. | SILUKO | 530 | 510 | 540 | 540 | 560 | 570 | 570 | 520 | 530 | 530 | 520 | 510 | 540 | 540 | 540 | 510 | 510 | 560 | 560 | 560 | 570 |
7. | GRA | 270 | 336 | 300 | 300 | 312 | 330 | 330 | 280 | 285 | 280 | 300 | 310 | 320 | 330 | 328 | 300 | 270 | 300 | 330 | 330 | 335 |
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h tto:llwww.'lser .org
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132/33 KV
33KV
33/11 KV
33/11 kv 33/6.6 KV
33/11 kv
33/11 kv
33/ 11
Kv
33/ 11
Kv
ETETE
GRA
NEKPENEKPEN
UGBOWO
IKPOBA
GUINNESS SILUKO
Fig. 1.0 Network diagram for Benin City
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