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The study assessed manufacturing system optimization using computer-based control kanban loops. The study assessed JIT's effect on average throughput-time, demand fill rate, net operating income for a certain product mix complexity and manufacturing overhead level. ARENA/SIMAN and WITNESS simulation tools were used to study implementation. The Drug Process Plant's JIT system reduced end buffer inventory, shortened customer lead time, and improved visual control. The mean response of the simulated new physical system in terms of NOI was 85.54 but gave a mean response of 85.30 when implemented on the shop floor. The mean response of the simulated new physical system in terms of cycle time was 617 but gave a mean response of 634 when implemented on the shop floor. Simulated new physical system in terms of DFR gave a mean response of 93.11 when implemented on the shop floor. Overwhelmingly, the new JIT system outperformed the old physical system. Bangladesh J. Sci. Ind. Res. 57(4), 221-228, 2022

The paper presented a hybrid micro-grid renewable energy of different energy sources to generate uninterrupted electricity for the Agu-Amede village using PV, diesel, biogas, and battery. The system optimization was performed to determine techno-economic analysis and energy generated using HOMER software. The energy generated by the hybrid system was able to meet the demand load of the village at all levels of biomass production with surplus electricity in each case when the production of the biogas system varied between 0.5 tons to 3 tons. At biomass production of 3 tons, the total energy generated demand is 480693 kWh with a surplus of 121762 kWh. Again, the hybrid PV and biogas system generate total energy of 98714 kWh (20.50%) and 381979 kWh (79.50%), respectively. The net present cost (NPC) and cost of energy (COE) of the base case architecture (diesel) measured are $1230000 and $0.267/kWh, respectively. Therefore, between 2.5 tons and 3.0 tons of biomass penetration, the energy production of biogas increased, and the diesel system was removed from the hybrid system setup. This is because the availability of biogas is almost sufficient to meet the load demand at a lower cost and solar PV architecture was added to the hybrid system to balance energy production.

The paper addresses the means of overcoming the challenge posed by voltage collapse to the stability of the Nigerian electric power system. The technique applied is based on time identification algorithm elaborating, at a given grid bus, the local phasor measurements at fast sampling rate. Elements such as adjustable shunt compensation devices, generator reactive generation, transformer tap settings are optimally adjusted at each operating point to reach the objective of minimizing the voltage stability index at each individual bus as well as minimizing the global voltage stability indicator. The control elements setting were optimized and the maximum possible MVA voltage stable loading has been achieved and a best voltage profile was obtained. Results of tests conducted on a 6-bus IEEE system and a typical 28-bus Nigerian power distribution network are presented and discussed. Keywords: Special protection systems, voltage stability analysis, voltage stability limit, voltage collapse mechanism, system security

A robust high-speed sliding mode control (SMC) of three phase permanent magnet synchronous motor (PMSM) is presented. The SMC served for inner speed control while a simplified hysteresis current control (HCC) scheme was used in the outer current control to generate gating signals for the inverter switches. The present research leverages on the ability of SMC to directly access system speed error which it attempts driving to zero by cancelling modelling uncertainties and disturbances. Performance comparison was done for the SMC model and an existing model having classical PI controller. With the initial positive speed command of 200 rpm at 5 Nm constant loading, rotor speed with SMC neatly settled to the reference speed at 0.085 seconds without overshoot while the rotor speed of the model with PI controller settled at 0.217 seconds after overshoot. This translates to 155.3% speed enhancement. Similar superior speed performance of the SMC was also observed during recovering from sudden speed reversal. While the SMC model recovered and settled to the reference speed of -200 rpm at 0.369 seconds, the model with PI controller settled at 0.482 seconds. From the results, it can be seen that SMC demonstared superiority over the conventioanl PI controller for complex drives systems.

[EN] An attempt has been made for the analysis on Circuit breakers (CBs) this paper. First, the types and arcing phenomenon of Oil and SF6 Circuit breakers were briefly discussed. However, various CBs were analyzed in terms of certain outage frequencies and reliability indices to ascertain the most reliable CB. This was possible using data collected from the 33kV Transmission Company of Nigeria (TCN) New Haven, Enugu. After the analysis, Emene Industrial CB had the highest value of availability of 0.9999 and the lowest tripping report while Ezillo had the highest failure rate of 0.1032., The authors are immensely grateful for the financial support from “African Centre of Excellence (ACE-SPED) University of Nigeria, Nsukka” to enable us to achieve the research (Muncho J. Mbunwe et al., 2019-2021).

A stand-alone roof-top solar-PV power supply is a viable and cost effective alternative to expensive and unreliable grid electricity to improve the quality of life by rural dwellers. This paper aims at highlighting the techno economic benefit of a stand-alone solar system as a viable option for production of electricity in South Eastern Nigeria. Emii is a village situated South Eastern Nigeria at Latitude 5.4511° N and longitude 7.1003° E and at an altitude of 106m. PVsyst software was used to carry out the economic analysis and it was found that the cost of energy of the stand-alone system was better than the unreliable grid supply having 0.098 $/kWh and 0.114$/kWh respectively. The Performance ration obtained from the sample was 0.653 and the solar fraction for the system is 98%. 30.802 tons of carbon emission was saved making the environment friendlier for inhabitants and payback period of 3.1years

With the ever-increasing complexity of disturbed Power Systems, the method of protection using electromagnetic relays may not be adequate to afford appropriate discrimination especially when the fault current flows in parallel paths. Because the electromagnetic relay has slow response time, and the fact that it is a mechanical device and has moving parts, over a period of time, these moving parts will wear out and the relay will fail. To overcome these drawbacks, a more reliable means of system protection was carried out using solid-state contactless devices. A modular technique using five blocks made up of power supply unit, current sensor unit, voltage sensor unit, switching unit and output unit were used in the study design. A 66 kV power network was used to test the reliability of the protection designed circuit. Result shows enhanced system security.

Electricity generation in Nigeria is based on thermal and hydro generation, and is largely dominated by two sources - non-renewable thermal (natural gas and coal) and renewable water or hydro. Coal and natural gas make up the largest portion of energy production in Nigeria. The fact that a reliable power station is one which would supply the required power within its installed capacity at any time within the specified voltage and frequency limits remains vital to our economic growth, personal well-being. Essential for this evaluation are the station’s installed capacity and available generation. As the gap between supply and demand on electric energy amplifies in Nigeria, it becomes necessary to carry out the optimal reliability performance of renewable energy powered turbine generators that control the electric power industry in Nigeria. The work focuses on the past data for performance of some power stations in Nigeria from 2006 to 2017 to determine their reliability and availability of energy within their installed capacities in line with energy global best practices. The combined installed capacity of these power plant is 37% of the twenty-one thermal power plants connected to the national power grid. A historical operational data of these selected plants over a period of twelve years was obtained and evaluated based on power plant performance indices analytical techniques. The relative index of equipment reliability obtained in this study, for Afam I–V, Afam VI, Delta and Egbin are (17.13, 78.57, 34.42, & 70.17) percent accordingly. It also shows that Afam VI and Egbin power stations have good workable preventive maintenance programmes whereas, Afam I–V and Delta power stations were always faced with corrective maintenance.

The provision of reliable electricity supply in both developed and developing nation is one of the primary needs for socio economic development of that nation. This paper turn’s to solve by way of introducing indigenous technology hybrid solar/Wind/Diesel Power system that will harness the natural renewable energies from the Sun and Wind to generate electricity. Renewable energy resources are a favourable alternative for rural energy supply. In order to handle the fluctuating nature, hybrid systems can be applied. The 2007–2016, 9 years solar radiation data, and the 2007–2016 data for wind speed for Potiskum in Yobe State of Nigeria, were collected. The two parameter Wielbull distribution was used to simulate power in watts per meter square densities for the 9 years period. Load estimates of a typical rural community and for rural ICT infrastructures were estimated. The step by step design of a 15 kW solar power supply system and a 10 kW wind power was done as a sample case. The results showed the average exploitable wind power density of 54.5 W/m2 average mean speed of 8.04 m/s. It was found that with the exception of monsoon months, August and September, solar energy can be utilized throughout the year for North-Eastern region of Nigeria. Therefore, the development of hybrid wind-solar system for off grid communities will go a long way to improve socio economy lives of people in that community.

The inability of power system to maintain a proper balance of reactive power is the major cause of voltage collapse. A system can be saved from voltage collapse by reducing the reactive power load or by adding additional reactive power into the system. The electric power system is afflicted with continuous load shedding due to inadequate generation and transmission capacities. To maximize the amount of real power that can be transferred over a network, reactive power flow must be minimized. Thus, sufficient reactive power should be provided locally in the system to keep bus voltages within stipulated ranges to satisfy customers’ equipment ratings. This paper presents an overview in reactive power compensation skills which remains as research challenges in this area. Newton-Raphson’s solution method was used to carry out the analysis because of its fast convergence, sparsity, and simplicity attributes when compared to other solution methods, with relevant data obtained from Power Holding Company of Nigeria (PHCN). MATLAB/SIMULINK was used to carry out the simulation analysis. It is observed that the application of compensation on the unified system jointly has effect on the other buses. This is confirmed by a step-by-step application of compensation at 5% intervals. The effects were noticed in Bus (20) where voltage decreased from 0.9568 to 0.9329 p.u. about 2.39%, bus (19) from 0.998 to 1.1035 p.u. and others. These results indicate undershoot and overshoot that will cause damage to the system, and may lead to system collapse if no contingency control is installed. It is also observed that compensation should be done on weak buses only for better results. The results indicate the enhancement in voltage profile in addition to reduction in the network losses and more balanced system. Active and reactive power control greatly influence the electricity grid, thus, need adequate attention with the recent advent of integration of renewable energy into the grid.

The aim of this research work is based on the design and development of a motorized yam pounder for pounding yam, this research was considered because of the importance of pounded yam in Africa particularly in Nigeria and because of the time and energy wasted using the traditional mortar and pestle method of yam pounding. The research work aimed at eliminating the labour involved in traditional method of pounding. Through this improvement the possibility of food contamination by sweating while pounding will be control. This project work sought to design a yam pounder that pounds yam right from the peeled cooked stage in a pounding bowl with the help of an electric motor that transmits power through rotary motion together with the help of shaft. The pounding blades functions as the pestle. The machine is to be operated by electricity and it consists of shaft, electric motor, yam beaters or pounding blades, bowl and the frame. Low cost materials were used so as to make the machine affordable for average Nigerian homes, thereby improving the standard of living. In order to avoid food contamination stainless material were also incorporated for smooth and clean pounding before consumption.