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This work investigates the technical, economic and environmental feasibility of four solar – wind off grid hybrid renewable energy system (HRES) models to provide electrification for Okorobo-Ile town in Andoni Local Government Area of River State, Nigeria using the Hybrid Optimization of Multiple Electric Renewables (HOMER) software. In particular, investigation of the possible inclusion of a fuel cell (FC) system is performed. The four considered models are: pv/wind/battery (PWB); pv/wind/battery/gen-set (PWBG), pv/wind/fuel-cell (PWF) and pv/wind/battery/fuel-cell (PWBF). The best cost-effective configuration among the set of systems were examined for the electricity requirement of 677.75 kWh/day primary load with 99.1 kW peak load. Results obtained showed that the net present cost (NPC) are $615,664.95, $679,348.17, $778,834.22 and $3,534,850.54 respectively for the PWB, PWBG, PWBF and PWF. The cost of energy (COE) was lowest for the PWB with a value of $$0.158 and highest for the PWF with a value of $0.964. The renewable options—PWBF and PWF have higher long-term costs but offer cleaner emissions. In contrast, options with the Diesel-Powered Generator is cost-effective but has a high environmental impact in terms of greenhouse gas emissions and noise pollution. These emissions include 3,758 kg/yr CO2, 23.7 kg/yr CO and a total of 32.67 kg/yr of unburned hydrocarbons, sulfur dioxide, particulate matter and nitrogen oxides. Based on the results, a stand - alone HRES that consist of 166 kW PV panels, 3 wind turbines 29 batteries and 123 kW converter is found to be the best configuration for the village, as it leads to minimum net present cost (NPC) and COE. The PWB system offers the best choice for the community by balancing financial considerations with sustainability which is crucial when making energy system choices. Results also show that while hydrogen, FC system and the electrolyzer can be used together with or without batteries, inclusion of the FC system resulted in the high NPC due to their high cost of investment.

The torque profile of a double-stator permanent magnet (PM) synchronous machine of 90 mm stator diameter having different rotor pole numbers as well as dual excitation is investigated in this paper. The analysis includes a comparative study of the machine’s torque and power-speed curves, static torque and inductance characteristics, losses and unbalanced magnetic force. The most promising flux-weakening potential is revealed in 13- and 7-rotor pole machines. Moreover, the machines having different rotor/stator (Nr/Ns) pole combinations of the form Nr = Ns ± 1 have balanced and symmetric static torque waveforms variation with the rotor position in contrast to the machines having Nr = Ns ± 2. Further, the inductance results of the analyzed machines reveal that the machines with odd rotor pole numbers have better fault-tolerant capability than their even rotor pole equivalents. A prototype of the developed double-stator machine having a 13-pole rotor is manufactured and tested for verification.

The analysis of cogging torque, torque ripple and total harmonic distortion of a permanent magnet (PM) flux-switching machine having separate excitation stators is presented in this study. Further, the effect of unbalanced magnetic force (UMF) on the rotor of this machine is also investigated. A comparison of the analysed machine having different rotor pole configurations is also given. The analysis shows that the largest cogging torque, torque ripple as well as total harmonic distortion (THD) are obtained in the four-rotor-pole machine while the least of THD and torque ripple effects is seen in the thirteen-rotor-pole machine. Furthermore, the evaluation of the radial magnetic force of the machines having an odd number of rotor poles shows that the investigated machine having a five-rotor-pole number exhibits the highest value of UMF, while the smallest amount of UMF is obtained in an eleven-rotor-pole machine. Similarly, it is observed that the machines having an even number of rotor poles exhibit a negligible amount of UMF compared to the ones of the odd number of rotor poles. [ABSTRACT FROM AUTHOR]

Comparison of the electromagnetic performance of a flux-switching permanent magnet (PM) machine having two separate stators as well as different winding topologies is investigated in this paper. Different stator and rotor pole combinations of these machines are also considered. The analysis includes the open-circuit and on-load characteristics of the analyzed machines. It is observed that, the largest fundamental values of electromagnetic torque, for each winding topology, is seen in the 11-rotor-pole and 10-rotor-pole machines having alternate- and all-pole-wound configurations, respectively. Moreover, significant ripple is observed in the waveforms of the even-number rotor pole machines compared to their corresponding odd-number rotor pole counterparts. Overall, the alternate-pole-wound machines essentially have larger torque-density than their equivalent all-pole-wound ones. The investigated machine is also tested for validation. [ABSTRACT FROM AUTHOR]