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PublicationControl strategies of power electronic converter for grid-tied variable low-speed wind turbine(AIP Publishing Ltd., 2023)With the increased penetration of wind energy on modern power systems, Wind Energy Conversion Systems (WECS) are required to participate actively in capturing the maximum wind energy and operating electric networks through a suitable control strategy. This paper provides the design and implementation of control strategies for Fully Controlled Power Electronic Converter (FCPEC) associated with a Variable Low-speed Wind Turbine (VLSWT) system. The considered system consists of a Wind Turbine (WT) and Permanent Magnet Synchronous Generator (PMSG) that are linked to the grid via an FCPEC. The control schemes of the FCPEC include a Maximum Power Point Tracking (MPPT) algorithm, a Machine Side Converter (MSC) control, and a Grid Side Inverter (GSI) control. To validate the effectiveness of the implemented control strategies, the considered system was modelled and simulated using MATLAB/Simulink under Malaysia wind speed profiles (2 m/s - 6 m/s). The simulation results proved that the MPPT algorithm and MSC control have successfully forced WT to operate at the optimal power coefficient of 0.44 further improved the maximum power available from the wind system that can be obtained. Besides, the results showed the capability of the GSI controller in improving the system performance in both steady-state and disturbance operating conditions. The dc-link voltage regulation and power integration to grid, with a unity power factor regardless of wind speed variation, were successfully accomplished.
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PublicationFEA-Based simulation of accelerated ageing in a power cable due to sustained partial discharge activities in a Spherical Cavity(Springer, 2023)The reliability of electrical assets is greatly influenced by the quality of their insulations. Key power installations such as power cables are manufactured with polymer-based materials as part of their insulation system. However, accelerated ageing of equipment insulations due to manifestation of defect(s), and partial discharges (PDs) can offset the operation of these systems or even lead to breakdowns. In this study, a non-deterministic model to simulate the phenomenon of repetitive discharges in a spherical air-filled cavity within a practical power cable has been investigated. In addition, the work contributes to the understanding of PD behaviour and field distribution under different ageing conditions considering changes in cavity surface conductivity. First, a section of the practical XLPE cable containing the cavity is developed in 2D using COMSOL software, and a finite element analysis (FEA) of the electric field distribution within the cable insulation is performed. The magnitude of the cavity local field, that is enough to ignite a PD, is investigated. Alongside the COMSOL model, the activity of sustained internal PD is simulated in MATLAB by introducing a random sample generating factor and adjusting the model’s parameters to obtain something close to the practical results. Furthermore, the impact of continuous PD in the power cable under different cavity dimensions and surface conductivity is likewise investigated, and a phase resolved PD (PRPD) pattern is established. The result shows that the magnitude and number of PDs per cycle increase as the cavity size and its surface conductivity increase. Finally, when the cavity surface conductivity rises, the amplitude of the electric field generated by the surface charge distribution and the number of PDs per cycle approach their maximum values.
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PublicationComparative analysis of conventional and modern high-rise hotels in Penang based on hourly simulation of cooling load performance using DesignBuilder(Semarak Ilmu Publishing, 2023)The study examines the energy efficiency performance of hotel façades in relation to the annual cooling load simulation. In achieving the objective, two case studies of high-rise city hotels are selected within the locality of Penang, Malaysia. The case studies are selected based on the year of construction coupled with the architectural styles encompassing conventional and modern design of hotel facades. In traditional hotel facades, passive design elements, including proper window and wall materials selection alongside window-to-wall ratio (WWR), are less significant. Comparatively, elements of passive design in modern hotel facades are notable. In assessing the thermal performance of the hotel façade, a case study of the conventional and modern high-rise city hotels in Penang are selected to undergo hourly cooling load simulation in the hotel guestroom using the DesignBuilder simulation program in establishing the hotel’s energy efficiency performance. The findings revealed the average annual cooling energy of the conventional and modern high-rise city hotel guestrooms is 553 kWh/m2 and 538 kWh/m2, respectively. The study concludes the elements of passive design, including WWR, window material selection, and external wall colour are crucial in determining energy-efficient hotel operations.
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PublicationEnhancing COVID-19 classification accuracy with a Hybrid SVM-LR model(MDPI, 2023)Support ector achine (SVM) is a newer machine learning algorithm for classification, while logistic regression (LR) is an older statistical classification method. Despite the numerous studies contrasting SVM and LR, new improvements such as bagging and ensemble have been applied to them since these comparisons were made. This study proposes a new hybrid model based on SVM and LR for predicting small events per variable (EPV). The performance of the hybrid, SVM, and LR models with different EPV values was evaluated using COVID-19 data from December 2019 to May 2020 provided by the WHO. The study found that the hybrid model had better classification performance than SVM and LR in terms of accuracy, mean squared error (MSE), and root mean squared error (RMSE) for different EPV values. This hybrid model is particularly important for medical authorities and practitioners working in the face of future pandemics.
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PublicationPotential of industrial internet of things (IIoT) to improve inefficiencies in food manufacturing(AIP Publishing Ltd., 2023)The aims of this review were twofold, namely 1) to analyze the main operational inefficiencies in food manufacturing and 2) to identify the main IIoT-related technologies with their potential operational improvement for the food manufacturing sector. An analytical literature review was performed using the main scientific literature databases as the secondary data source. The review has found nine major operational issues that are most frequently reported in the food manufacturing sector namely 1) too long manufacturing lead time, 2) low productivity, 3) absence of systematic quality management, 4) low compliance to food safety requirements, 5) lack of innovations in product development, 6) lack of training, 7) unsustainable marketing strategies, 8) poor traceability and 9) lack of documentation along the supply chain. While IIoT is relatively new, it is important to embrace that food manufacturing can have many of these operational issues solved when incorporating digital technologies. The key starting point is the identification of the correct and effective application that suits the industry's requirements in their pursuit of an improved level of operational efficiencies, productivity and a higher level of quality. In this regard, this review intended to clarify the identified seven groups of IIoT technologies that could improve the above-identified operational issues, whereby these are 1) smart manufacturing technologies, 2) Big Data, Analytics and Artificial Intelligence, 3) robotics, 4) additive manufacturing, 5) augmented reality, 6) manufacturing simulation, and lastly 7) the cloud. The study concluded that food manufacturers could only benefit from the IIoT advantages when the purpose of the technology fulfils their operational objectives and requirement as well as fits within their constraints