Electrical Engineering

Saw Dust Ash (SDA) is an industrial waste that has been used by many researchers in concrete to achieve economic and environmental sustainability. In this study, 5% of sand was replaced with SDA to produce concrete with different mix ratios. Scheffe's simplex theory was used for five mix ratios in a {5,2} experimental design which resulted in additional ten mix ratios. Additional fifteen mix ratios were generated from the initial fifteen, for verification and testing. Concrete cubes of 150mmX150mmX150mm were formed using the thirty concrete mix ratios generated, and soaked in water for 24hours. The water absorptions of cubes from each mix ratio were determined with the standard procedure. The results of the first fifteen water absorption values were used for the calibration of the model constant coefficients, while those from the second fifteen were used for the model verification using Scheffe's simplex lattice design. A mathematical regression model was formulated from the results, with which the water absorptions were predicted. The model was then subjected to a two-tailed t-test with 5% significance, which ascertained the model to be adequate and fit with an R2 value of 0.8244. The study also revealed that SDA can replace 5% of sand and promote environmental sustainability without significantly changing the water absorption.

The effect of curing conditions on the compressive strength, surface absorption and permeability of concrete containing admixtures was investigated. Five mixes were designed: a control mix and four admixtures; waterproofer, chloride free accelerator, two superplasticizersPolycarboxylate Ether (PCE) and Sulphonated Naphthalene Formaldehyde condensates (SNF) were used. M30 concrete of 0.55 water cement ratio (w/c) and 150180mm slump was designed as the control mix. Appropriate water reduction was made for mixes with admixtures to obtain the design slump. The concrete samples were separated into two; water and air cured samples. Compressive strength was tested at 3, 7 and 28 days; whereas Initial Surface Absorption Test ISAT and High Pressure Permeability Tests HPPT, were done at 28days. Results reveal that adequate curing is essential for optimum concrete performance even in mixes containing admixtures. In addition, the effects of improper curing is more manifested on durability param...

In this paper, a novel approach to voltage collapse analysis using a probabilistic predictor-detector that relies on a conditioned probabilistic Quadratic Line Voltage Stability Index coined the q-LVSI and a moving average filter coined pq-LVSI for deductive analysis of power system network state. The proposed technique uses simple rules for logical analysis such as ratio-sum-of-thresholds, mean-value analysis and confidence conditioning to detect and estimate the presence of a collapsing signal from a sequence of several qLVSI estimates and for several simulation runs. A moving average filter consisting of long-term and short-term predictions is used to filter and enhance the predictions from the resulting q-LVSI values prior to probabilistic logical analysis. The technique is applied to some interconnected buses of the Nigeria power system network in order to determine the interconnected bus sequence(s) that are most likely to collapse. Simulations are performed in the MATLAB lang...

The study assessed the performance improvement of New-Road-Okilton by Ada-George electric power
distribution system consisting of twenty-three (23) distribution transformers. The network was modelled
in Electrical Transient Simulation software (ETAP12.6) and load flow performed using Newton-Raphson
technique. The result obtained from the pre-upgrade network shows that buses [17(0.949pu),
18(0.948pu), 19(0.947pu), 20 (0.947pu), 21(0.946pu), 22(0.946pu) and 23(0.945pu)]violates thebus
voltage statutory limit conditions 0.95-1.01pu. Also, the transformers that are loaded above 80% are as
follows:- [4(107.67%), 5(118.33%), 6(113.67%), 11(106.33%) and 21(107.67%)]. Real and reactive
power losses on the line are 130.978KW and 161.086kvar. However, tap setting the transformer LTC,
upgrading overloaded transformers and placement of capacitor bank improved the voltage profile of the
buses [17(0.982pu), 18(0.981pu), 19(0.981pu), 20(0.980pu), 21(0.980pu), 22(0.980pu) and 23(0.980pu)],
also improved the load profile of the transformers [T4(64.6%), T5(69.0%), T6(68.2%), T11(63.8%) and
T21(64.6%)]and the real and reactive power losses in the line have been reduced to 81.94KW and
94.359kvar. It is thereby concluded that the proposed optimization techniques impacted significantly in
the improvement of the distribution network.
Key word:Buses, Capacitor bank,Distribution network, Losses, Substation, Voltage profile,
Transformer LTC setting

Abstract:This paper presents an analysis of reliability assessment for some area of electrical energy
distribution system in Port Harcourt using analytical approach being supported by Electrical transient analyzer
tool (ETAP) in order to run simulation on reliability assessment of the system. The investigation considered
station-road, Amadi-North, floor-mail and Borikiri substation for purpose of analysis and verification. From the
simulation results from system indices of ASAI: 0.9986pu, SAIFI: 0.7840 f/customer.yr, SAIDI:
12.66440hr/customer.yer, CAIDI: 16.128 hr/customer interruption in 2016 and ASAI: 0.9990pu, SAIFI:
0.78208/customer, yr. SAIDI:12.7740 hr/customer.yr, CAIDI: 16.108hr/customer interrupting in 2017. The
reliability indices of the substations under study as obtained from the anlaysis, revealed that the reliability of
the distribution system is below the set standard. Evidently improvement technique will be recommended in
order to strengthen the activity of the system.
Keywords: reliability, distribution network, power supply, meantime to repair (MTTR), outage duration,
meantime to between failure (MTBF)

This paper presents an analysis of reliability assessment for some area of electrical energy
distribution system in Port Harcourt using analytical approach being supported by Electrical transient analyzer
tool (ETAP) in order to run simulation on reliability assessment of the system. The investigation considered
station-road, Amadi-North, floor-mail and Borikiri substation for purpose of analysis and verification. From the
simulation results from system indices of ASAI: 0.9986pu, SAIFI: 0.7840 f/customer.yr, SAIDI:
12.66440hr/customer.yer, CAIDI: 16.128 hr/customer interruption in 2016 and ASAI: 0.9990pu, SAIFI:
0.78208/customer, yr. SAIDI:12.7740 hr/customer.yr, CAIDI: 16.108hr/customer interrupting in 2017. The
reliability indices of the substations under study as obtained from the anlaysis, revealed that the reliability of
the distribution system is below the set standard. Evidently improvement technique will be recommended in
order to strengthen the activity of the system.

This research work express how fuzzy logic controller was developed to detect on a single line to ground fault, double line to ground fault, line to line fault and three phase fault are detected on Notore fertilizer plant 11KV distribution. Line and Substations in Onne, Rivers State, Nigeria was used as case study. The proposed fuzzy logic controller takes neutral, phase currents, current in the Red phase (IR), current in the Yellow phase (IY), current in Blue phase (IB) and current in the Neutral phase (IN) and phase voltages. Voltage in the Red phase (VR), voltage in the Yellow phase (VY) and voltage in the Blue phase (VB) as inputs. The inputs are assigned three linguistic variables (Low (L) Normal (N) and High (H)) with some degrees in triangular membership function. Also a single output (Fault) was assigned to the controller with ten linguistic variables [Red phase to ground fault (RG), Yellow phase to ground fault (Y-G), Blue phase to ground fault (BG), Red to Yellow phase fault (R-Y), Red to Blue phase fault (R-B), Yellow to Blue phase fault (YB), Red and Yellow phase to ground fault (RY-G), Red and Blue phase to ground fault (RB-G), Yellow and Blue phase to ground fault (YB-G), and Three phase fault (3-Ø) with varying degree of triangular membership function. Next, the Mamdani expert system were used for the implementation while the outputs of the ten rules were aggregated to form a defuzzified output with the help of Centre of gravity method. The results were displayed on a scope at every instant of fault occurrence on the network.

The idea to generate electricity at minimum cost for purpose of economic dispatch is a strong consideration for generating power operation and system planners in the power industry and utilities. The major cost of running generating power plants, is the fuel cost while other cost may be added to the fuel cost, the fuel cost ($/h) or (N/h) which is a function of the power generation in (MW). The fuel cost curve required in this analysis is the parabolic curve function. The derivation of the cost-function evidently shows that the incremental fuel-cost curve, analysis of the slope of the fuel cost curve need to be minimized. The incremental fuel-cost curve indicates how expensive it will be to generate the next increment of power (MW). Therefore, simple operating cost for economic dispatch and coordination equation techniques were used and validated with Matlab application which shows the individual cost of operations for increment cost of each generating capacity (MW).

This paper proposed two scenario, the 1 st scenario look at the analysis of transient stability study of 330KV super-grid voltage level of Nigerian power system network. Considering Alaoja (load-bus), Onitsha (load-bus) and Afam power station (generating-bus) referred as study case, from the Nigerian 330KV transmission grid (network) for purpose of investigation and findings. The analysis is based on swing-equation model approach and power transfer capability conditions. The activities of fault initiated were recorded as "sustained fault" classified with respect to time setting of the protective relay and circuit breaker operations from Afam power generating station (GS) to the 330KV network in order to measure the behaviour of the turbine rotor-angle with the clearing time setting of the relay. The collected data were simulated via Matlab platform, with the clearing time setting of (t = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50) corresponding to the respective deviation of the rotor swinging angles of (rf1, rf2, rf3 and rf4). Where rf1 defined the deviation of the rotor-angle of the turbine power plant due to sustained fault condition with time, t. while rf2, rf3, and rf4; defined the restoration ability of the deviated rotor-angle (rf1) from instability to gradual progressive stability condition, with fault cleared at 2.5cycle (rf2), 6.5 cycle (rf3) and 8.25cycle (rf4) respectively. The 2 nd scenario also look at the analysis of three (3) phase short-circuit faults including: (phase A, phase B; phase C respectively) in a Matlab coded environment. The results of the simulated fault condition shows that, there is strong need for short-circuit fault-clearing time which should be quick for relay and circuit breaker responses (sensitivity and selectivity-based). The revelation of the finding also shows that system instability will be restored for improvement at fault clearing time before 0.05s. Evidently, further work will look at the investigation of incremental loading condition of the turbine power plant.

Relay coordination is a means by which a relay closest the point of fault operates, but in the event of failure the backup relay operates in sequence to provide backup protection. This research was a detailed improved relay coordination in Port Harcourt Distribution Network using RSU 2 X 15MVA, 33/11kv Injection Substation as a case study. This work is of high practical importance to the society and country in general. The research methodology included the collection of relevant data from Port Harcourt Distribution Company and Transmission Company of Nigeria and provision of appropriate parameters using appropriate equations required for the short circuit analysis. The Electrical Network was modelled in Electrical Transient Analyzer Program 12.6 Software. The short circuit was embedded in ETAP 12.6 software to determine the sequence of operation of relays for the existing network (Existing Case). The sequence of operation event report showed that tripping sequence violation occurred in 2 (two) relays with each tripping the associated CB at 12.3ms for fault on Ojoto 11kv feeder or RSU 11kv feeder and 12.1ms for fault on Federal 11kv feeder or Wokoma 11kv feeder while the successive relays tripped theirs first at 10.2ms and 10.1ms respectively. The sequence was in the order of 1, 3, 2 and 4. Tripping sequence violation was eliminated in the New Case in the order of 1, 2, 3 and 4. The New Case showed improved relay coordination.

The power flow investigation of Agip Estate  Mile 4, 33kv Distribution Network was analysed using Newton-Raphson method was used for the  power flow equation while Microsoft Excel was used  to justify the current and Electrical Transient  analyzer program (ETAP) software was used for the  Pre-Upgrade and the Post-Upgrade simulation. The  result shows that the power factor, frequency on each Transformers, transformer percentage loading,  transformer current, active power, reactive power  and apparent power, respectively were determined. The Pre-Upgrade current from Bus to Bus, the  nominal voltage of the feeders, respectively was also  considered. The post-upgrade of the system was  actualized using transformer load tap changer  optimization techniques. We concluded that the  power system future planners should plan with best  operating condition by up-grading the distribution  transformers, using transformer load tap changer while feeder bifurcation were found to be effective in improving voltage profile of the weak buses, reduce losses and eliminate over loading from the system.  Indexed Terms- Electrical Transient Analyzer  Program (ETAP) Software, Feeder Bifurcation, Transformer Load Tap Changer Optimization Techniques, Pre-Upgrade and Post-Upgrade.

This paper formulated the framework of
optimization of electric power generation for expansion
planning and cost saving. The inability of the power systems
in developing countries to generate enough electric power
has led to extra-ordinary power losses on the line due to the
over load dependence thereby making the power system
planning and running cost outrageous. This paper
considered the application of decomposition techniques for
an optimization search in order to break-down the capacity
allocation (that is, the forecasted load or energy demand for
twenty (20yrs) projection was determined, which served as
the input data for the capacity allocation to the generating
stations especially in a developing country like Nigeria,
include the following capacities of generating
stations:2250MW Afam power, 2350MW Sapele power and
3000MW to Egbin power as expected power to be generated
from these stations).  The paper examined the existing
capacity of the generating stations and considered a
capacity-mix combination as: (200MW, 250MW and
300MW) which served as the input data: row-element
matrix while the column-element matrix need to be
determined or factor-out into different number of unit
combination arrangement to achieve different options for the
best selection. Five optimization plans was developed with
respect to five different number of unit-combination
arrangement  in order to have a total respective operational
cost of the following: N
8,176,503,40,800,
N7,654,267,24,800, N7,499,530,60,800, N7,460,846,44,800
and N5,206,095,83,900. The research paper strongly
identified the functional relationship between capacity and
cost this shows that as capacity of  the generating plant
increases, the operational running cost of the power plant
also increases this is being validated with two-tail test and
spearman’s rank correlation coefficient with (
R
: 0.99375)
approximately +1 which shows that there is a correlation
k
that exist between capacity and cost

An analysis was performed for the improvement of electrical power supply to Trans-Amadi Industrial Layout, Port
Harcourt, which consists of ten feeders operating at 33KV level. Transmission and distribution transformer voltage ratings from
supply station to the study case was used. Network layout from the supply to the study case with transmission and distribution
feeders data were also considered. Electrical Transient Analyser Program (ETAP) was not left out. The ETAP was employed for
modelling and simulation of the network. Analysis using voltage drop equations was carried out, determination of transformer
loading level on different feeder and buses was also done. Also adequate design was done for the proper size (rating) of the
capacity bank to be placed in the network for improvement. It was found out that the buses were operating within acceptable
voltage limits. The airport and Rumuodomaya transformers with loading level of 127 and 74.76 percent  respectively were
overloaded. The Akani, Rainbow and Trans-Amadi transformers with 5.377, 6.49 and 1.821percent loading conditions respectively
were critically underloaded. It was concluded that the system needed improvement. Therefore, it was suggested that additional
transformer should be added to the overloaded feeders or buses, the existing 300KVA capacity transformers on the network should
be upgraded to 500KVA. It was also recommended that critically underloaded 500KVA capacity transformer should be replaced by
300KVA capacity and that the power factor of the network be improved by placement of capacitor bank.

This paper considered a long term electric power load forecast for twenty years (20 years) projection, in Nigeria power system using least-square regression and exponential regression model. The model is implemented in Matlab platform with a plot in residential load demand, commercial load demand and industrial load demand in (MW). In the quest for analysis and predicting the energy (power) demand (MW) requirement for a projection period of (2013-2032), data are collected between (2000-2012), from the Central Bank of Nigeria (CBN), and National Bureau of statistics (NBS). The results obtained shows that energy generated from the respective generating station including Egbin thermal power station Lagos, Sapele thermal power station etc. are grossly inadequate. This mismatch is a major problem in power system planning and operation. The result also shows that there is deviation between predicted energy demand (MW) and available power (or capacity allocated). The predicted energy demand into the projected future of 20years is 45 5,870.2MW. The paper work also extended the prediction form into: leastsquare, exponential regression model. Evidently, the comparism plot for linear and exponential model which shows similar predicting pattern: particularly least-square exhibit linear behavior, while exponential shows non-linear behaviour, the linear model gives more accurate result as compared to the exponential.

Electrical generator are device that convert mechanical power to electrical power. The conversion depends on types of generator and its parameters.it stability depends on the loads connected and the frequency of the system. When a system excited, some amount of energy is being generated thereby causing the rotation on the system. The excitations on this machine is examine in this work. The Matlab Simulink has been use to ascertain the effect of excitation on the machine. The excitation affect the system depending on its types. The analysis on this paper has been done for the different types of excitation mode such as normal, under, over and critical excitation and their effects on the machine. This effect causing the system in stability especially on critically excited mode which causes the system to stabilized at a higher time than every others. This in stability effect can causes a damage to the system and the loads on which it is feeding. The results from the simulations revealed that the critical excitation can affect both the machine and the loads connected to it.

Adaptive filtering constitutes one of the core technologies in digital signal processing and has numerous application
areas in science as well as in the industries. Adaptive filtering techniques are used in a wide range of applications,
including echo cancellation, adaptive equalization, adaptive noise cancellation, and adaptive beam forming.
Acoustic echo cancellation is a common occurrence in today’s telecommunication systems. The signal interference
caused by acoustic echo is distraction to users and causes a reduction in the quality of the communication. The
method used in carrying this research work is known as the normalized least mean square. This focuses on the use
of the combination of Finite impulse response digital filter and Normalized least mean square algorithms to reduce
this unwanted echo, thus increasing communication quality. This research work further did some comparative
analysis of Finite impulse response digital filter, Least mean square, Normalized least mean square. But the
improved Normalized least mean square adaptive filter response obtained in this research work turns out to be a
positive result, with the highest signal to noise ratio and lower mean square error at 0.2 steps and 25 filter size. We
are also recommending this method to be used in noise elimination in hearing aids, electrocardiograph systems,
communication industries and any area that requires noise cancellation.

This study analysed the effects of
conductor transposition on the 132kv Alaoji-Port
Harcourt transmission lines. This study was
motivated on the grounds that the inductance and
capacitance of conductors will not be equal if they
are not transposed at regular intervals. When
parallel conductors, such as power lines, are run in
parallel with transmission lines, excessive voltages
can be induced in the lines. As a result, acoustic
shock or noise may occur. This unfavourable
phenomenon is considerably reduced by
transposition. Also, the Spacing between conductors
in a transmission line is not same in practice which
also causes limitation in the transmission of energy.

The analysis of transmission lines under fault condition represents one of the most important and complex task in Power Engineering.
The studies and detection of these faults is necessary to ensure that the reliability and stability of the power system do not suffer a
decrement as a result of a critical event such a fault. This project conduct a research, analyse and evaluate the behaviour of a transmission
lines under fault conditions and evaluate different scenarios of faults.  This was done using ETAP 16. Fault is an abnormal condition
that involves an electrical failure of power system equipment operating at one of primary voltage within the system. It was revealed that
three-phase fault, the voltages at faulted buses phases dropped to zero, voltage at Phase A is equal to zero in single line-to-ground fault
double line-to-ground fault, Phase B and C voltages are equal to zero and this type of fault is the most sever fault on the system. Positive
sequence bus 1, has the lowest resistance of 2.80435 Ω and impedance of 12.003 Ω, bus 57 has the highest resistance of 63.5967 Ω,
with the highest reactance of 59.4 Ω in bus 57 and bus 2 has the lowest reactance of 11.296 Ω and the highest impedance of 86 .99 in
bus 57. Negative sequence, bus 1 has the lowest resistance of 3.24 Ω, lowest reactance of 11.161 Ω and lowest impedance of 11.622
and bus 57 has the highest resistance of 63.95 Ω, highest reactance and impedance of 57.4 Ω and 85.92 Ω respectively.
For zero sequence impedance, the lowest resistance is in bus 1 with the value of 1.076 Ω, the lowest reactance of 3.41 Ω and the lowest
impedance of 3.541 Ω. The highest resistance is bus 3 with the values of 117.65 Ω, the highest reactance is bus 57 with the v alue of
85.89 Ω and the highest impedance in bus 3 with the value of 122.16 Ω.

The short circuit analysis study is a research conducted for Forcados Shell Petroleum Development Company (SPDC), Nigeriapowerdistribution network. Itisnecessaryforplanning, operation, futureexpansionas fault current level increases in electrical power systems due to increase in load demand, introduction of Distributed Generations (DGs) and increase in network interconnections.Theanalysiswascarried outfor appropriate selection of protection devices such as Circuit Breaker (CB), Fuse, Superconducting Fault Current Limiter (SFCL) tosolvetheproblemoffrequentpower outagescharacterized with massive resultant current and fall in voltage and frequency.Adetailed survey wascarried outontheNetworkandthePer-unit Impedance (P.I) method was used to determine the system short circuit currentand theElectrical Transient Analyzer Program (ETAP) wasalso usedtomodelthenetworkandcarryoutsimulationtocomparetheresults.Itwasobservedthat, bothresults obtainedweresimilar.The resultant short circuit current at the downstream bus-3 is 3.328KA and the upstream bus-1 20.462KA.Theresults gottenoneachbuswill aidthe protectionengineerduring protection scheme,operationandfutureexpansionofthenetworkunderconsideration.