Microgrid, Its Control and Stability: The State of The Art

Some of the challenges facing the power industries globally include power quality and stability, diminishing fossil fuel, climate change amongst others. The use of distributed generators however is growing at a steady pace to address these challenges. When interconnected and integrated with storage devices and controllable load, these generators operate together in a grid, which has incidental stability and control issues. The focus of this paper, therefore, is on the review and discussion of the different control approaches and the hierarchical control on a microgrid, the current practice in the literature concerning stability and the control techniques deployed for microgrid control; the weakness and strength of the different control strategies were discussed in this work and some of the areas that require further research are highlighted

A Rough Set Approach to Dimensionality Reduction for Performance Enhancement in Machine Learning

Machine learning uses complex mathematical algorithms to turn data set into a model for a problem domain. Analysing high dimensional data in their raw form usually causes computational overhead because the higher the size of the data, the higher the time it takes to process it. Therefore, there is a need for a more robust dimensionality reduction approach, among other existing methods, for feature projection (extraction) and selection from data set, which can be passed to a machine learning algorithm for optimal performance. This paper presents a generic mathematical approach for transforming data from a high dimensional space to low dimensional space in such a manner that the intrinsic dimension of the original data is preserved using the concept of indiscernibility, reducts, and the core of the rough set theory. The flue detection dataset available on the Kaggle website was used in this research for demonstration purposes. The original and reduced datasets were tested using a logistic regression machine learning algorithm yielding the same accuracy of 97% with a training time of 25 min and 11 min respectively

The Effects of Plastic Waste Materials on the Physical and Strength Properties of Floor Tiles

Human activities often generate solid waste, such as plastics. The disposal of this waste is usually a setback. This paper aimed to examine the viability of using plastic waste and white cement to produce floor tiles. Waste was collected from waste disposal facilities within Benson Idahosa University. The materials were cleaned and dried, and plastics were shredded. Waste materials were then mixed with white cement in different ratios. Compressive strength tests were performed to verify the suitability of utilising these solid wastes to make floor tiles. Shred plastics that were passed through a sieve with an average diameter of 1 to 2 mm were utilised. The cubes were cast and cured for 7, 14, and 28 days. The compressive strength of the cubes was tested using a universal testing machine. The study found that the addition of up to 50 % of cement resulted in a more than a 10-fold increase in the compressive strength of the cast cubes. On the other hand, the inclusion of plastics reduced the compressive strength of the cubes. Furthermore, increasing the number of plastics increased water absorption, whereas larger amounts of cement reduced water absorption. Plastics are a common waste produced by man; hence, they are easily accessible and a very economical material to produce floor tiles

Design and Hybrid Simulation of a Larceny Deterrent Energy Evaluation System

The unreliability of the energy system to provide a proper account of energy utilized by consumers has been a huge burden on the distribution system network. Different metering methods and designs to detect and prevent fraud, employed in the past have proven fruitless, thus signalling the need for a much smarter energy metering system. The most frequent problem is electricity larceny, this has incurred a major economic loss in the energy distribution system. To this end, this paper presents the distinctive design and hybrid simulation of a larceny deterrent energy evaluation system, capable of detecting different methods of energy theft within power consumer premises. The method employed comprises of deep understudy of previous work in this field, a model is proposed and is simulated under good working conditions and several theft situations using MATLAB while the hardware is simulated using Proteus 8.1 and Arduino software. In conclusion, the efficiency of the proposed system is evaluated by employing different electric theft algorithms, with the results indicating significant energy cost savings in the distribution network

Design and Fabrication of a One Stand Hot Tandem Rolling Mill

Over the years, metalworking processes have emerged as a promising paradigm to modify materials' intrinsic workability and microstructural evolution. However, due to the stringent requirement of the state-of-the-art, non-uniform original grain structure of the metal ingot comprising large columnar grains growth in the direction of solidification, resulting in brittleness, weak grain boundaries, shrinkage, porosity, etc. remain a major bottleneck. This paper proposes a novel metalworking process to overcome this challenge. In particular, a one-stand hot tandem rolling mill that can break the grain structure and destroy the boundaries having uniform grain structures is developed. The proposed one-stand hot tandem rolling mill was constructed using 60 mm diameter work rolls, 150 mm diameter backup rolls, 120 mm diameter spur gears, a 3 hp electric motor, and a 50 mm diameter shaft. The components were installed, and the roll was fixed at a roll gap of 60 mm. Experimental investigations using a 65 mm aluminium sheet metal at a draft of 5 mm per pass after heating the metal sheet above its re-crystallization temperature were performed to validate the superiority of the proposed model. Available results indicate a robust improvement in the toughness, strength, and resistance of materials. Specifically, the results showed an efficiency of 86 % at an average draft of 4.3mm per pass

The Effect of Metal Inert Gas Welding Parameters on the Weldability of Galvanised Steel

The Taguchi technique is employed to establish the optimal parameter for each tensile property of the weldments. The tensile properties determined are the ultimate tensile strength, the yield strength, and the percentage elongation, whereas the process parameter used is the welding current (A), welding voltage (B), and the gas flow rate (C). By applying the Taguchi method, the optimal process parameters for obtaining the weldment with better yield strength are A3B1C3, whereas A3B3C3 can produce the weldment for better elongation. These optimum process parameters have shown considerably improved signal-to-noise ratios over the current process parameters adapted by the welders

Land Tenure Systems and Agricultural Productivity in Nigeria: A Case of Rice Production

This study examined land tenure systems and rice productivity in Nigeria. Primary data were used for the study. Data were collected with the aid of a well-structured questionnaire. A four-stage sampling technique was used to select a total sample size of three hundred and forty-nine (349) rice farmers for the study. Data were analysed using descriptive statistics, total factor productivity, and the Stochastic production frontier model. The study revealed that a large portion of the land (over 94%) used for rice production was acquired through inheritance mode of land acquisition and communal type of land tenure system widely practised. The result of total factor productivity indicated that 62.18% of the rice farmers were at a sub-optimal productivity level. The results of the stochastic production frontier function revealed that seed (P< 0.10), and fertilizer application (P<0.01) were the significant factors influencing the technical efficiency of rice production in the study area. Based on the findings, the study recommends that the current land use act and policy should be amended to prevent concurrent grabbing of agricultural land for non-agricultural purposes to enhance the availability and accessibility of land for agriculture

Optimization of the Tungsten Inert Gas Process Parameters using Response Surface Methodology

Optimization is a very important techniques applied in the manufacturing industry that utilizes mathematical and artificial intelligence methods. The complexity associated with most optimization techniques have resulted to search for new ones. This search has led to the emergence of response surface methodology (RSM). The paper aims to optimize tungsten inert gas process parameters required to eliminate post-weld crack formation and stabilize heat input in mild steel weldment using RSM. The main input variables considered are voltage, current and speed whereas the response parameter is Brinell hardness number (BHN). The statistical design of experiment was done using the central composite design technique. The experiment was implemented 20 times with 5 specimens per experiment. The responses were measured, recorded and optimized using RSM. From the results, it was observed that a voltage of 21.95 V, current of 190.0 A, and welding speed of 5.00 mm/s produced a weld material with the following optimal properties; BHN (200.959 HAZ), heat input (1.69076 kJ/mm), cooling rate (72.07 /s), preheat temperature (150.68 ) and amount of diffusible hydrogen (12.36 mL/100g). The optimal solution was selected by design expert with a desirability value of 95.40 %

Impacts of Ambient Temperature Change on the Breakdown Voltage of a Distribution Transformer

The aim of this paper is to determine the effects of ambient temperature variation on the breakdown voltage of a distribution transformer. Three different insulation oil samples (naphtha mineral, paraffin mineral and silicon base transformer oil) were collected from six distribution transformers (300 – 500 kVA) across two business units (Asaba and Ugbowo) of Benin Electricity Distribution Company during May and June, 2017. The oil samples were analysed using the 60 kV Megger OST60PB portable oil tester, to determine the trend of breakdown voltage of the oil insulation under varying temperature. A 3rd order polynomial model was deduced for each sample type with coefficient of determination within the range of 96.99 – 99.95 %. The observed average breakdown voltage is 43.6 kV (for naphtha base mineral transformer oil), 42.2 kV (for paraffin base mineral transformer oil) and 46.8 kV (for silicon base transformer oil) within the temperature range (26˚C – 32˚C). The result indicates that the breakdown voltages of the considered transformer oil types are satisfactory but the silicon base transformer oil has the best breakdown voltage

Thermodynamic Studies on the Sorption of Lead (II), Chromium (III) and Manganese (II) ions onto Acid-Activated Shale

Shale mineral in its raw form was collected, processed, calcinated and activated using tetraoxosulphate (VI) acid. The microstructural arrangement and chemical composition of the raw, calcinated and acid-activated shale was determined using x-ray fluorescence and scanning electron microscope to verify its ability for the removal of Pb2+, Cr3+ and Mn2+ from wastewater. Batch experimental method was used to study the effect of different adsorption parameters on the sorption efficiency of shale. The effect of temperature on the sorption of Pb2+, Cr3+ and Mn2+ on acid-activated shale was investigated at varied temperature of 15 – 40 . The calculated value of enthalpy () was 12.50 kJ/mol for Pb2+ adsorption, 5 kJ/mol for Cr3+ and 11 kJ/mol for Mn2+ adsorption. The calculated values of Gibbs free energy () varies from -6.576 kJ/mol to 1.358 kJ/mol for Pb2+ adsorptions, from -2.696 kJ/mol to 0.192 kJ/mol for Cr3+ adsorptions, and -4.994 kJ/mol to 1.870 kJ/mol for Mn2+ adsorptions. The entropy () range is 38.68 – 60.946 kJ/mol for Pb2+ adsorptions, 16.69 – 24.58 kJ/mol for Cr3+ adsorptions, and 31.70 – 51.10 kJ/mol for Mn2+ adsorptions. The positive value of  shows that the adsorption of Pb2+, Cr3+ and Mn2+ onto acid-activated shale was an endothermic process. The values of  are negative at temperature of 298 K and above for the three metal ions studied, which confirmed that the adsorption of Pb2+, Cr3+ and Mn2+ on acid-activated shale was a spontaneous process. The decline in  with increasing adsorption temperature showed that adsorptions of Pb2+, Cr3+ and Mn2+ onto acid-activated shale became better at higher temperature while the positive value of  for all metal ions studied showed the amplified arbitrariness at the solid-solution interface during the fixation of the adsorbate on the active site of acid-activated shale