Wind energy potentials of some selected high altitude and coastal areas in Nigeria are assessed for possible utilization for the generation of electricity. The main aim is to provide pragmatic insight that will enhance the investment in wind energy conversion systems in an optimal manner. The data used in this present study were obtained from the Nigeria Meteorological Agency, which includes average wind speeds per day of four locations across the country, measured at the anemometer height of 10 m over a period of 11 years. With the sites classified based on their wind power densities, the capacity factor estimation value was used to select the most suitable turbine for the selected sites, and the present value cost method was employed to estimate the unit cost of energy of the turbine at various hub-heights. The results obtained from this study reveal that Jos, Kano and Ikeja are economically viable as well as having excellent wind resources integration into the grid, while P/H is viable for a standalone application. The outcome of the study provides useful information that will aid renewable energy policymakers in Nigeria for wind energy development.
Power quality problem such as unbalanced voltage have adverse effects on the satisfactory performance of three phase induction motors which are the main work horses in many industrial, commercial and residential applications. The new models of three phase induction motor and adjustable speed drives are highly susceptible to unbalance voltage. Detecting whether the supplied voltage to these machine is balanced or unbalance is very vital, if the service life and motor efficiency will be maintained for a reasonably numbers of years. This paper applied Artificial Neutral Network for detection of voltage unbalance. ANN was satisfactorily trained with 100 samples of real-time voltage readings supplied to three phase induction motors. The collected data were the fed to the trained ANN for classification. The results of the analysis showed that 26.25% were detected to be balanced voltage while 73.75% were tagged unbalanced. It was observed that Mean Squared Error (MSE) was found to be 0.084321, Root Mean Squared Error (RMSE) was found to be 0.781885 and percentage accuracy was 100% for balanced and unbalanced voltage.
Reactive power compensation on radial distribution systems is a challenging issue. Electric power distribution systems are being bedeviled by high active power loss and severe voltage violation especially on the buses that are far from distribution substations. This article presents a two-stage approach for sizing shunt capacitors and identifying the locations where their placement would be most beneficial within radial distribution systems. A multiobjective function capturing real power loss minimization and bus voltage profile enhancement was formulated and weighted approach was engaged to transform the function into single objective one. While backward forward sweep approach was used for the load flow analysis, loss sensitivity factor was employed to predetermine suitable sites for capacitor installation, with the optimal sites and sizes determined using cuckoo search algorithm. This approach was implemented on IEEE 15-bus and Yale 17-bus/11 kV feeder.Results obtained using the method was thereafter compared with those obtained through other methods as obtained from literature and the comparison shows that cuckoo search algorithm outsmarts others. Significant reduction in real power loss, coupled with appreciable enhancement in voltage profile, is achieved on the Yale 17-bus/11 kV feeder. The approach is therefore viable for addressing reactive power compensation problems confronting practical radial distribution systems.
K E Y W O R D Sbackward forward sweep, cuckoo search algorithm, loss sensitivity factor, radial distribution system, shunt capacitor
Investigated in this study is harnessing the heat energy absorbed by photovoltaic (PV) solar cells for electricity generation, in order to boost the electric power output of rooftop PV power system, without expending on cooling the energy conversion devices. An experiment was carried out in which a metallic plate was attached to the back of a low rate rooftop PV installation to capture the waste heat of the PV array and evenly distribute the heat to the conversion devices. Four commercial thermoelectric generator (TEG) modules were attached to the plate for the conversion of the heat to electricity. The modules were passively cooled and connected in parallel. Outputs of the PV array and the TEG bundle were obtained on a data logger while the experiment lasted for 11 weeks during a sunny season in Nigeria. Voltage and current up to 2.5 V and 4 A, respectively, were obtained from the harvested heat, while the PV-TEG combination operated at higher efficiency than that of the PV alone. Potential of rooftop PV system in hot climates is thus maximized by the passive cooling. The approach could be improved further using metal plate with higher conductivity.
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