Towards realizing the United Nations sustainable development goals, access to clean, cheap and reliable energy, especially electricity, has been considered as one of the vital indices in any community. Hence, this paper presents the design analysis of both a grid-connected and an offgrid photovoltaic (PV) systems for household users in the highly residential city of Ogbomoso in Nigeria using PVGIS software. For the off-grid design, it is estimated that, given a total daily load of 9.57 kWh, a 3.5 kWp PV array size and a battery capacity of 86 kWh are enough to power the load  with 5 days of autonomy and 70% depth of battery discharge. For the grid-connected PV system, the annual energy output for a building-integrated PV system is found to be around 4006 kWh; and a total of eight PV modules (each rated 250 Wp, 30.93 V) are stringed to arrive at the desired capacity of 2 kWp. In terms of performance, the performance ratio (PR) of a building integrated grid-tied PV system at the study location was found to be 71.2% while for a free-standing PV system, the PR was 75%.

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Energy demand has constantly been on the rise due to aggressive industrialization and civilization. This rise in energy demand results in the massive penetration of distributed generation (DG) in the distribution network (DN) which has been a holistic approach to enhance the capacity of distribution networks. However, this has led to a number of issues in the low voltage network, one of which is the voltage rise problem. This happens when generation exceeds demand thereby causing reverse power flow and consequently leading to overvoltage. A number of methods have been discussed in the literature to overcome this challenge ranging from network augmentation to active management of the distribution networks. This paper discusses the issue of voltage rise problem and its impact on distribution networks with high amounts of distributed energy resources (DERs). It presents different DG technologies such as those based on conventional and unconventional resources and other DERs such as battery storage systems and fuel cells. The study provides a comprehensive overview of approaches employed to curtail the issue of voltage increase at the point of common coupling (PCC), which includes strategies based on the network reinforcement methodology and the active distribution network management. A technoeconomic comparison is then introduced in the paper to ascertain the similarities and dissimilarities of different mitigation approaches based on the technology involved, ease of deployment, cost implication, and their pros and cons. The paper provides insights into directions for future research in mitigating the impact of voltage rise presented by grid-connected DGs without limiting their increased penetration in the existing power grid.

Distribution transformer being major equipment in utility companies deserves to be routinely scrutinized for its performance with a view to ensure continuous supply of energy to end-users as well as to sustain improved revenue collection by the utility company. Presented in this paper is the real time assessment of 500-kVA, 11/0.415 kV distribution transformer situated at Bells University of Technology, Ota, Ogun State using power quality and energy analyzer equipment. The parameters measured on real time include phase to neutral voltage, phase to phase voltage, root mean square and peak current, frequency, active power, reactive and apparent power and line power factor. The assessment revealed wide variation of system voltages far from the standard, however, the line power factor and as well as frequency of operation was observed to be within the standard. Based on this analysis, several findings and appropriate recommendations were suggested to improve the supply of energy in the study area. It is hope that the findings of this research will be of immense benefit to distribution engineers at the Department of works in Bells University of Technology, Ota for field compliance.

Induction motors (IMs) are the most widely employed electrical motors due to their robust construction and adaptability. Due to their versatility and wide range of applications, it is crucial to examine the performance of these motors using a simple but thorough simulation model. In this study, we present the simulation models to conduct the DC test, the no-load test, and the locked rotor test on a three-phase induction motor using MATLAB/Simulink. These three tests are fundamental to determining the characteristics of a three-phase induction motor equivalent circuit. Furthermore, the authors extend the model to determine the starting current, starting torque, and breakdown torque of the motors under inquiry. The research further employs the right code in the MATLAB environment to ascertain the motors' torque-speed and current-speed properties. The results of the simulations are found to closely match the values achieved in real trials. Hence, this model can be employed to enhance teaching and research in the field of electrical machinery. Article Highlights This paper explains a computerized procedure employing MATLAB software to carry out vital tests on induction motors. The research shows that using the methods described in this paper, induction motors can be safely tested for their operating characteristics. The benefit of the computerized methodology described in this paper is that it provides a modelling tool and methodology to expand research on induction motors with high accuracy and reliability. The numerical method developed in this article is a suitable tool in teaching and education. Beyond the three common tests (dc test, no-load test and locked rotor test) to determine the equivalent circuit of induction motors, this paper further extends the research to use the simulation models to determine the starting current, starting torque and the breakdown torque of an induction motor as well as its torque-speed and current-speed characteristics.