International Journal of Engineering Research in Africa Vol. 44

Abstract: The presence of adequate renewable energy resources and the rapid development of wind projects in South Africa have led to mapping out of the country’s wind capability. In view of this, the economic prospects of utilizing wind energy as a potential energy alternative in South Africa are examined and discussed from the perspectives of green energy strategies for sustainable energy development. This research work is designed to investigate the economic effects of using the wind turbine (WT) in ten locations in South Africa based on the grid planning and power sector reform. The HOMER application software is utilized in this study to assess the wind resources on provincial and national scales, along with estimating the annual energy generation of the selected locations. The wind energy potential of South Africa is analysed by utilizing the capacity factor (CF), wind penetration and mean output of the WT for various locations in South Africa. The results obtained from the study indicate that the selected sites fall within the range of Class 1V of IEC wind classifications with the annual average wind speed of 4.04 m/s for Pretoria and 6.39 m/s for Cape Town at 50m hub heights. The economic assessment of the WT for electric power generation is carried out by using some key performance indicators (KPIs) such as net energy purchased, energy sold, revenue, grid energy purchased, annual utility bill savings, net present cost (NPC) and cost of energy (COE). It is established from the study that Cape Town is the most suitable location for installation of the WT by utilizing the same load profile and system configuration. The output of this research work can be used by the renewable energy development agencies as inputs to harness the potential of wind resources for strategic planning of the power sector reform and industrial development.

Abstract: Development of small hydropower plants depends on its economic and financial feasibility, which must be evaluated by cost estimates before construction. Cost of electromechanical (EM) equipment represents the major portion of the total plant budget. The paper presents new cost estimation approach for EM equipment of hydropower plants. Compared to the literature approaches, the proposed cost correlation is elaborated basing on dataset of hydropower plants located in different continents. Furthermore, the transport cost has been considered of continental factors. Mono-and multi-objective genetic algorithm (GA) optimization have been both applied and compared to determine the best cost correlation. The accuracy of this best cost correlation is validated by using statistical analysis tools to compare it with the equation deduced from the best model reviewed in the literature. The results have shown that the bivariate correlation, viz., the Pearson Product Moment Correlation Coefficient (PPMCC), is slightly improved from 98 % to 99 %. The Mean Square Relative Error (MSRE) is substantially improved from 4.47 % to 1.82 %, and the Utmost Square Relative Error (USRE) from 45.2 % to 11.4 %. Indeed, the proposed cost correlation gives a more accurate estimate of EM equipment cost of hydropower plants in different continents.

Abstract: Inverter based Distributed Energy Resources lack the inertia and damping features of synchronous generators dominated traditional power system. The growing penetration of renewable energy technologies coupled with their inherent intermittency also constitute grid instability challenge due to insignificant inertia and damping. The virtual inertia machine methods for the control of inverter based Distributed Energy Resources present the required inertia support that mimics the dynamic performance of a typical synchronous generator. These control methods provide excellent improvement in the stability of the grid. Several studies and implementations have been carried out on providing virtual inertia support for inverters in steady-state and under balanced grid voltage, however there is a need to investigate the dynamic performances during voltage sags occasioned by faults and other grid transients. Due to the low overvoltage and overcurrent tolerance capabilities of inverters, this investigation is important to observe the inverter transient behavior while ensuring the protection of constituent power electronic switches. Consequently, this work carried out an investigation to assess the two methods of Virtual Inertia Machine in ensuring the inverter sustained grid connection in compliance with grid codes, fault current limitation and fault recovery.

Abstract: Optimal Power Flow (OPF) problem is one of the most important and widely studied nonlinear optimization problems in power system operation. This study presents the implementation of a new technology based on the hybrid Firefly and krill herd method (FKH), which has been provided and used for OPF problems in power systems. In FKH, an improved formulation of the attractiveness and adjustment of light intensity operator initially employed in FA, named attractiveness and light intensity the update operator (ALIU), is inserted into the KH approach as a local search perform. The FKH is prove with the solving of the OPF problem for various types of single-objective and multi-objective functions such as generation cost, reduced emission, active power losses and voltage deviation which are optimized simultaneously on exam system, viz the IEEE-30 Bus test system, which is used to test and confirm the efficiency of the proposed FKH technique. By comparing with several optimization techniques, the results produced by using the recommended FKH technique are provided in detail. The results obtained in this study appear that the FKH technique can be efficiency used to solve the non-linear and non-convex problems and high performance compared with other optimization methods in the literature. This study can achieve a minimum objective by finding the optimum setting for system control variables.

Abstract: In recent engineering practices, the manufacturing industries are more technically able to produce product with high quality to desire the customer needs. For accomplishing customer needs many lean tools are used to improve the methods of manufacturing practices in industries. The aim of this research work is enhance the productivity of spool casing assembly used in horn armature core per shift by using method study, time study and VSM. Cycle time for each operation of the product is determined by time study and the value added, non-value-added activities and transportation wastes occurred in the current state process identified and plotted in the current state VSM. The future state VSM was developed to reduce unnecessary wastes such as transportation, inventory, waiting which occurred in the current state VSM. Both current and future state time study are simulated using Flexsim simulation software. From the observed results it was found that, P3 and P5 model productivity was improved by about 5.5% and 6.5% respectively after implementation of appropriate lean tools.