International Journal of Engineering Research in Africa Vol. 48

Abstract: As it stands, in terms of environmental impact and efficiency, photovoltaic (PV) energy has appeared to be a potential renewable power source that notably contends with the traditional power generation schemes. More so, a noteworthy factor that contrariwise influences the PV module efficiency is the PV module temperature. Therefore, the more the PV module temperature increases, the lesser the PV module efficiency. More importantly, the impact of undesired spectrum wavelengths on the PV module temperature is further reduced by passive optical filters, nonetheless, active optical filters which is more superior to the passive type, based on the PV module temperature and output power during the day, dynamically change the cut-off wavelength. Consequently, the efficiency as well as the lifecycle is both enhanced by controlling the active optical filter so as to attain optimal output power. Therefore, in this paper, a wavelength-based thermo-electrical model of a PV module was designed and simulated, the essence of this model is mainly to predict the impact of each module wavelength on both the temperature and the output power of the PV module. In view of this, since the output power is affluence by the module temperature, it is expedient to design a controller that locates the optimal cut-off spectral wavelength to lessen the module temperature whereas getting the most out of the output power over a period of time. In this vein, we designed a Model Predictive Controller whose objective is to maximize the output power by simply controlling the input power through filtering the spectrum wavelength for a photovoltaic (PV) system. The design and simulation of the plant model as well as the MPC controller were carried-out on MATLAB/Simulink environment.

Abstract: The use of Substation Communication Networks (SCN) in power distribution centres of thermal power plants for protection, control and monitoring is increasing as industry’s confidence grows in the application of the IEC-61850 based Substation Automation Systems (SAS). IEC-61508, which is the standard for functional safety, addresses Electrical/Electronic/Programmable Electronic (E/E/PE) safety based technologies in so far as safety lifecycle as well as reliability and verification of safety related systems are concerned. It follows therefore, that Substation Communication Networks (SCN), as well as associated substation equipment that forms part of the overall safety system should satisfy the requirements of functional safety standard IEC-61508. In this paper, Substation Automation System standard (SAS) IEC-61850, Substation Communication Networks (SCNs) as well as dependability evaluation methods are reviewed and discussed.

Abstract: With the increasing penetration of the distributed generation driven by renewable energy in distribution systems, there is a need to analysis fault currents for the next generation utility and smart grid systems. The steady state fault current contribution from Type 4 wind turbines is not calculated accurately by traditional short circuit analysis techniques. A new formulation for calculating the short circuit current sharing from voltage source converter wind turbines is presented, and taken into consideration the real behaviour of the type 4 WT during three phase short circuit in the electric system. The results are compared with that obtained from the dynamic simulation results using Power World Simulator program, which has the generation of Western Electricity Coordinating Council (WECC) generic model. The percentage difference between the two results is about one percent that verify the effectiveness of the proposed formulation

Abstract: The present paper gives an accurate iterative methodology for optimal sizing of a hybrid photovoltaic/wind system with battery storage, using the concept of the loss of power supply probability and the total net present cost. In the first part, the optimum combinations that can meet the load demand while respecting the desired loss of power supply probability level are determinate, following two steps: First, all feasible solutions are determinate. Second, each feasible solution is optimized iteratively.In the second part, the optimal solution which has the lowest net present cost is selected based on an economical study. Lastly, the proposed and adopted methodology is verified and discussed with the meteorological data of the area of Hawaria (Tunisia) to prove its fast computation time and good convergence accuracy.

Abstract: In current scenario, all the manufacturing industries are placing constant efforts for their endurance in the current global volatile economy. Manufacturing industries are annoying to implement new and professional techniques in their regular production processes. Some of the recognized tools are applied and their awareness has been growing among the industries, especially in production sector. Last two decades have witnessed an explosion in the area of quality and productivity improvement initiatives in the manufacturing industries by different tools and techniques such as lean manufacturing, total quality management, total productive maintenance, six sigma implementation etc. The objective of this study is to enlighten the importance of lean techniques implementation in a medium scale belt manufacturing industry. This research study helps to exhibit the existing hidden potential in the selected industry as well as a selection of appropriate techniques for productivity improvements. Also, it aims to eradicate wastes and non-value added activities at every stage in order to enhance the overall productivity. From the results after implementation of appropriate lean techniques it was found that, the lead time was reduced about 1256 minutes and the overall production was increased by about 9%.