Showing papers by "Nasrudin Abd Rahim published in 2019"

Towards Sustainable Energy: A Systematic Review of Renewable Energy Sources, Technologies, and Public Opinions

Abstract: The use of renewable energy resources, such as solar, wind, and biomass will not diminish their availability. Sunlight being a constant source of energy is used to meet the ever-increasing energy need. This review discusses the world's energy needs, renewable energy technologies for domestic use, and highlights public opinions on renewable energy. A systematic review of the literature was conducted from 2009 to 2018. During this process, more than 300 articles were classified and 42 papers were filtered for critical review. The literature analysis showed that despite serious efforts at all levels to reduce reliance on fossil fuels by promoting renewable energy as its alternative, fossil fuels continue to contribute 73.5% to the worldwide electricity production in 2017. Conversely, renewable sources contributed only 26.5%. Furthermore, this study highlights that the lack of public awareness is a major barrier to the acceptance of renewable energy technologies. The results of this study show that worldwide energy crises can be managed by integrating renewable energy sources in the power generation. Moreover, in order to facilitate the development of renewable energy technologies, this systematic review has highlighted the importance of public opinion and performed a real-time analysis of public tweets. This example of tweet analysis is a relatively novel initiative in a review study that will seek to direct the attention of future researchers and policymakers toward public opinion and recommend the implications to both academia and industries.

Performance Comparison of Fault-Tolerant Three-Phase Induction Motor Drives Considering Current and Voltage Limits

Abstract: With the increasing demand for electric vehicles, reliability in motor drives is an issue of growing importance. Over the years, various fault-tolerant three-phase motor drive topologies have been introduced and their performances have been investigated. Evaluation of the postfault power of a fault-tolerant drive should take into account both the postfault torque and speed, which depend on both the postfault current and voltage limits. Nevertheless, the postfault motor voltage limits are usually omitted from discussion. Furthermore, current limit in induction motor drive is not as direct as that in permanent magnet motor drive, due to the presence of the flux current. In this paper, the performances of available fault-tolerant three-phase induction motor drives have been reinvestigated, taking into account the impact of not just currents, but also voltage limits for both the inverter and machine. By deriving the postfault machine voltage equations, the effects of machine parameters and operating point on the voltage limit and hence the speed limit are explained. Depending on the topology, the motor may be able to run above the rated speed to gain extra power. The analysis is verified through experiment results on a 1 kW induction machine for four different fault-tolerant drive topologies.

Optimal sizing and energy scheduling of isolated microgrid considering the battery lifetime degradation.

Abstract: The incessantly growing demand for electricity in today’s world claims an efficient and reliable system of energy supply. Distributed energy resources such as diesel generators, wind energy and solar energy can be combined within a microgrid to provide energy to the consumers in a sustainable manner. In order to ensure more reliable and economical energy supply, battery storage system is integrated within the microgrid. In this article, operating cost of isolated microgrid is reduced by economic scheduling considering the optimal size of the battery. However, deep discharge shortens the lifetime of battery operation. Therefore, the real time battery operation cost is modeled considering the depth of discharge at each time interval. Moreover, the proposed economic scheduling with battery sizing is optimized using firefly algorithm (FA). The efficacy of FA is compared with other metaheuristic techniques in terms of performance measurement indices, which are cost of electricity and loss of power supply probability. The results show that the proposed technique reduces the cost of microgrid and attain optimal size of the battery.

Sizing and applications of battery energy storage technologies in smart grid system: A review

Abstract: Dynamics of the world are changing, and people are preferring low cost and reliable power throughout the day. The addition of renewable energy to the existing system is also one of the ways to provide reliable and cheap electricity. The existing bottle neck in transmission lines, continuous contamination of the environment due to heavy reliance on fossil fuels, and the highly fluctuating cost of fossil fuel are few reasons for the widespread use of renewable energy technology. Energy storage technologies are the need of time and range from low capacity mobile storage batteries to high capacity batteries connected to the intermittent renewable energy sources. Selection of different battery types, each having distinguished characteristics in power and energy, depends on the nature of power required and delivered. This paper presents a detailed review of battery energy storage technologies pertaining to the latest technologies, benefits, sizing considerations, efficiency, cost, and recycling. An in-depth analysis in terms of advantages and limitations between the different types of batteries is discussed and compared. In terms of microgrid application, the economic benefits of battery sizing using optimization and probabilistic methods provide a potential solution during the design stage by taking into account various factors affecting the sizing of the battery such as the degradation rate, reliability, and battery placement. This paper ends with the discussion on the recyclability of these batteries and their impact on the environment.

Fault-Tolerant Field-Oriented Control of Three-Phase Induction Motor Based on Unified Feedforward Method

Abstract: With the increasing proliferation of variable speed drive, the demand for the more reliable drive is also on the rise. Despite the growing interest on more advanced motors like permanent magnet and flux switching motors, three-phase induction motors (3ph-IMs) are still the main workhorse in the industry and hence the fault-tolerant control of these motor drives remains an interesting and important topic. In this paper, a simple fault-tolerant field-oriented control technique for 3ph-IMs is presented. It is shown that by injecting zero-sequence compensation voltage in a feedforward manner, open-circuit faults can be effectively tolerated. Compared to the previous feedforward fault-tolerant control methods, the proposed approach does not require the knowledge of the magnetizing inductance, which is tricky to be obtained in induction motors. Furthermore, the unified feedforward approach allows the same control structure to be used for different fault-tolerant 3ph-IMs drive topologies, with minor modifications to the feedforward terms. In addition, the effect of inverter non-idealities on the performance of the proposed control method is also highlighted and addressed. The effectiveness of the proposed controller is verified using MATLAB simulation and further validated using experimental tests. This paper is accompanied by a video demonstrating the experimental results.

Effect of nanofluids on heat transfer and cooling system of the photovoltaic/thermal performance

Abstract: Purpose Effective cooling is one of the challenges for photovoltaic thermal (PVT) systems to maintain the PV operating temperature. One of the best ways to enhance rate of heat transfer of the PVT system is using advanced working fluids such as nanofluids. The purpose of this research is to develop a numerical model for designing different form of thermal collector systems with different materials. It is concluded that PVT system operated by nanofluid is more effective than water-based PVT system. Design/methodology/approach In this research, a three-dimensional numerical model of PVT with new baffle-based thermal collector system has been developed and solved using finite element method-based COMSOL Multyphysics software. Water-based different nanofluids (Ag, Cu, Al, etc.), various solid volume fractions up to 3 per cent and variation of inlet temperature (20-40°C) have been applied to obtain high thermal efficiency of this system. Findings The numerical results show that increasing solid volume fraction increases the thermal performance of PVT system operated by nanofluids, and optimum solid concentration is 2 per cent. The thermal efficiency is enhanced approximately by 7.49, 7.08 and 4.97 per cent for PVT system operated by water/Ag, water/Cu and water/Al nanofluids, respectively, compared to water. The extracted thermal energy from the PVT system decreases by 53.13, 52.69, 42.37 and 38.99 W for water, water/Al, water/Cu and water/Ag nanofluids, respectively, due to each 1°C increase in inlet temperature. The heat transfer rate from heat exchanger to cooling fluid enhances by about 18.43, 27.45 and 31.37 per cent for the PVT system operated by water/Al, water/Cu, water/Ag, respectively, compared to water. Originality/value This study is original and is not being considered for publication elsewhere. This is also not currently under review with any other journal.

An application of TPB constructs on energy-saving behavioural intention among university office building occupants: a pilot study in Malaysian tropical climate

Abstract: Buildings account for a vast amount of energy consumption in Malaysia. Occupant behaviour patterns are a major factor affecting the energy performance of buildings. Identifying energy waste due to occupant behaviour will allow stakeholders to develop effective strategies to curtail energy consumption in buildings. The purpose of this study was to investigate the effects of theory of planned behaviour constructs on energy-saving behavioural intention among university building occupants. Data from a survey questionnaire was collected from 292 occupants (students and staff) at one case study building at a public university in Malaysia. Data analysed using the structural equation model showed that attitude and perception significantly influence occupants’ energy-saving behaviour. Our results indicate that respondents showed moderate behaviour on three sub-constructs: duration of equipment use, frequency of equipment use, and energy saving practice. The current pilot study provides a basis for an improved theoretical framework that considers other variables to be applied in a larger scale study. The implications for behaviour models in terms of policy recommendations and suggestions for occupant engagement campaigns are discussed.

Natural Sensitizers and Their Applications in Dye-Sensitized Solar Cell

Abstract: Many organic, inorganic and natural dye sensitizers have been trailed in the past in an attempt to reduce the cost, improve the performance and make the dye-sensitized solar cell (DSSC) technology more environment-friendly. Ruthenium-based complexes are by far the most efficient dye sensitizers and have been commercially used in DSSC technology and achieved approximately 12–14% conversion efficiency. But the problems associated with ruthenium complexes are high cost and toxicity which drive the researchers to identify new metal-free and environment-friendly dye sensitizers such as organic and natural sensitizers. In this regard, natural dye sensitizers due to their low-cost extraction and environment-friendly nature are becoming a new area of research in the field of DSSC technology. These dye sensitizers are naturally occurring dye pigments, such as chlorophyll, betanins, carotenoids, anthocyanins and tannins extracted from flowers, leaves, stems and roots of plants using water, acetone and/or alcohols. At present, the efficiency of natural dye sensitizers is quite low compared to ruthenium-based dye due to selective light absorption. Recently, highest recorded efficiency of 2% has been reported using cocktail of natural dyes extracted from flowers. Attempts have been made to improve the performance of natural dye sensitizers by making cocktails and/or by using a variety of solvents for the extraction of dye molecules.

IoT-Based Smart Air Conditioning Control for Thermal Comfort

Abstract: Thermal comfort brings a great influence that may affect the satisfaction of an occupant about the surrounding indoor environment, as this could led to the level of productivity and social interactions. One of the most suitable tools that have been utilized in tropical region to create thermally comfortable indoor environment is the air conditioning (AC) system. However, the conventional method of controlling the AC may not guarantee thermally comfortable indoor ambience, furthermore excessive cooling chosen by users may also contributed to negative side effect toward the occupancy’s health. To overcome this problem, an IoT-based smart system that can control the AC to provide a suitable thermally comfortable environment is proposed in this project. The system will interact with the users by recording their feeling toward the environment as the input for the system. Together with sensors’ data, the information will be integrated with an enhanced Predicted Mean Vote (PMV)-based model to control the AC smartly so that the occupant can feel thermal satisfaction. Based on the results, the IoT-based smart system can create a thermally comfortable indoor environment compared to the maximum cooling setting as usually being adapted by the room’s occupants.

A comprehensive review of reactive power control strategies for three phase grid connected photovoltaic systems with low voltage ride through capability

Abstract: Photovoltaic (PV) sources have recently become one of the most mature technologies. With the increasing penetration level and the integration of a PV system into the grid, the stability and reliability of the power networks have been serious concerns. Thus, grid codes are being released by grid operators for low voltage networks under grid faults. Consequently, the Low Voltage Ride Through (LVRT) capability of the grid connected PV system became the most important issue related to grid codes, i.e., more reactive power is injected into the grid during voltage disturbances. In this paper, a comprehensive review of reactive power control strategies for the three-phase PV system has been analyzed to support the grid during voltage sags by providing LVRT capability. The control techniques have been classified into three main categories: Fixed power factor, constant active power control, and constant reactive power control. The results illustrate that the stability of the system is improved when two control techniques are simultaneously implemented. This paper concludes that further research must be carried on LVRT control techniques for the reactive power injection during unbalanced voltage sags.

Forecasting Solar Power Using Hybrid Firefly and Particle Swarm Optimization (HFPSO) for Optimizing the Parameters in a Wavelet Transform-Adaptive Neuro Fuzzy Inference System (WT-ANFIS)

Abstract: Solar power generation deals with uncertainty and intermittency issues that lead to some difficulties in controlling the whole grid system due to imbalanced power production and power demand. The forecasting of solar power is an effort in securing the integration of renewable energy into the grid. This work proposes a forecasting model called WT-ANFIS-HFPSO which combines the wavelet transform (WT), adaptive neuro-fuzzy inference system (ANFIS) and hybrid firefly and particle swarm optimization algorithm (HFPSO). In the proposed work, the WT model is used to eliminate the noise in the meteorological data and solar power data whereby the ANFIS is functioning as the forecasting model of the hourly solar power data. The HFPSO is the hybridization of the firefly (FF) and particle swarm optimization (PSO) algorithm, which is employed in optimizing the premise parameters of the ANFIS to increase the accuracy of the model. The results obtained from WT-ANFIS-HFPSO are then compared with several other forecasting strategies. From the comparative analysis, the WT-ANFIS-HFPSO showed superior performance in terms of statistical error analysis, confirming its reliability as an excellent forecaster of hourly solar power data.

Photovoltaic Flyback Microinverter With Tertiary Winding Current Sensing

Abstract: This paper presents a new low cost, non-invasive, and isolated current sensing technique for the grid-tied photovoltaic (PV) flyback microinverter. This is accomplished by using the flyback transformer itself as a current sensor, achieved by introducing a tertiary winding to the flyback transformer. The mathematical integration of the tertiary winding's open circuit voltage through a ground-clamped-integrator results in the sensing of the magnetizing current. Since the magnetizing current is a combination of both primary and secondary current, control of both grid current and maximum power point tracking (MPPT) is implemented by sensing only the magnetizing current. This allows the PV, primary, secondary, and the grid current loops to be free of any invasive current sensors. Moreover, controlling the magnetizing current provides an alternative solution to an inherent problem with continuous conduction mode (CCM), the control complexity. Linear ramping and de-ramping of the magnetizing current allows for a set–reset hysteresis control to be implemented, resulting in CCM control simplicity that is akin to the boundary and discontinuous conduction mode. A grid-tied microinverter prototype is presented for verification, achieving the following experimental result: 1.9% grid current THD, 0.9988 power factor, above 99% static MPPT efficiency and dynamic efficiency of 98.50%.

Fault-Tolerant Symmetrical Six-phase Induction Motor Drive Based on Feed-forward Voltage Compensation

Abstract: Fault-tolerant multiphase drives have received plenty of attention from the research community over the past two decades due to the increased emphasis on reliability of power electronics and drives systems. Among different types of fault, open circuit or open phase faults have been well studied and different fault-tolerant control approaches have been proposed in the past. While fault-tolerant control based on closed-loop approach have been shown to give good performance, it is possible to tolerate open-phase fault using just simple feed-forward voltage compensation. In this paper, the operation of a multiphase induction machine during open phase fault is examined, and the fundamental factors affecting its performance are discussed. Based on the analytical discussion, it is demonstrated that by calculating x-y voltages and adding to the control voltage in feed-forward manner, torque oscillations due to open phase fault can be easily compensated. Compared to the closed-loop approach, the feed-forward method is superior is terms of simplicity and transient response.

Toward Cleaner Cities: Renewable Energy Initiatives in Malaysia

Abstract: As an oil-producing nation, Malaysia has long relied on fossil fuels for meeting the country’s energy demand. Nevertheless, understanding that over-relying on fossil fuel will have adverse effect to the environment and economy, Malaysian government began to look into potentials offered by renewable energy (RE) resources since the early 2000. Over the years, various policies have been drafted and implemented to grow the renewable energy sector in Malaysia. Recently in the Paris Convention, Malaysia together with other ratifying nations of COP21 has reinstated its commitments toward reducing greenhouse gas emission (GHG) and adopting cleaner energy. According to the Intended Nationally Determined Contribution signed, Malaysia has expressed the intention to reduce its greenhouse gas emission intensity of gross domestic product (GDP) by 45% by 2030 compared to that of 2005. Out of this pledged 45%, 35% is on an unconditional basis, while the remaining 10% will be fulfilled provided there is funding, technology transfer, and capacity building from developed nations (UNFCCC 2015).

Self-cleaning and weather resistance of nano-SnO2/modified silicone oil coating for photovoltaic (PV) glass applications

Abstract: The current investigation focused on the development of a new class of transparent nano-SnO2/modified silicone oil based coating with hydrophobic behavior and excellent self-cleaning properties for photovoltaic (PV) applications. SnO2 nanopowder was blended with silicon oil using isopropyl alcohol as a solvent which was then applied on the glass substrates using sponges. The treated glass plates were then subjected to water contact angle (WCA) measurement in order to determine the hydrophobicity of the modified glass. The results revealed the high WCA of 118° ± 2° displaying enhanced hydrophobic characteristic whereas, the UV–Vis analysis demonstrated an improved transmittance (99%) in visible region. Moreover, the prepared-coating also exhibited an excellent anti-fogging and wear-resistance behavior and was found to have insignificant changes in the WCA for 20 peeling cycles using scotch tape. Outdoor exposure’s results also confirmed that the nano SnO2–silicone oil coating on the glass panel possess superior durability against weather with WCA was 110° ± 2° and transparency > 92% in visible region even after 2 months of outdoor exposure.

Analysis of Photovoltaic String Failure and Health Monitoring with Module Fault Identification

Abstract: In this paper, photovoltaic (PV) string failure analysis and health monitoring of PV modules based on a low-cost self-powered wireless sensor network (WSN) are presented. Simple and effective fault detection and diagnosis method based on the real-time operating voltage of PV modules is proposed. The proposed method is verified using the developed health monitoring system which is installed in a grid-connected PV system. Each of the PV modules is monitored via WSN to detect any individual faulty module. The analysis of PV string failure includes several electrical fault scenarios and their impact on the PV string characteristics. The results show that a degraded or faulty module exhibits low operating voltage as compared to the normal module. The developed health monitoring system also includes a graphical user interface (GUI) program which graphically displays the real-time operating voltage of each module with colors and thus helping users to identify the faulty modules easily. The faulty modules identification approach is further validated using the PV module electroluminescence (EL) imaging system.

Optimal solar powered system for long houses in sarawak by using homer tool

Abstract: Ensuring electricity coverage for rural areas in Malaysia is still a big challenge due to the houses are in deep forest and scattered locations. The estimated coverage in 2015 is only 94% and still depending on conventional fossil-fuel generators. Considering full utilization of renewable source is highly recommended. Therefore, this paper proposes optimal design of full solar powered system for long houses in one selected area in Sarawak, Malaysia. Interestingly, the work has been started with evaluation and estimation of loads with site survey done to the selected area, which is Kampung Sungai Merah. The site visit has been conducted to survey and estimate the loads at the site. The design considers meteorological and climate data, specifications of system, and simulation configuration. HOMER tool is used in this work which comes with the optimization algorithm to search for the least cost system. The simulation results reveal the outcomes by considering three discount rates of 3%, 6% and 12%, and the system is presented with the best design for each rate. Lower discount rate contributes to higher PV and lower battery architectures as compared to higher discount rates. In short, it can be concluded that the system is optimally designed to be fully depended on utilization of solar as solid renewable source, which affects PV and battery architectures as two key design elements. Finally, this work should be able to provide the designer an opportunity to fully consider various options in developing the best renewable and full solar powered system for rural electrification.

Sensorless second-order switching surface for a three-level boost converter

Abstract: This paper proposes a sensorless second-order switching surface to control a three-level boost converter (TLBC). A predictive current method is proposed to reduce the number of sensors in the normal second-order switching surface method. Based on a developed model of the TLBC, the current is estimated and a switching surface is formulated in the state-energy plane. Simulation and hardware tests are carried out to verify the viability and the effectiveness of the proposed control technique. Results obtained show a good performance of the converter in term of DC-bus balancing and fast dynamic response under sudden load change.

Feedforward Fault-Tolerant Control for Three-Phase Induction Motor Drives with Single Open Circuit Fault

Abstract: Due to inevitable prospect of failure in power electronics, the demand for reliability improvement in adjustable speed drives become important, particularly for the induction motor drives being widely used in the industry. In this study, a mathematical approach is introduced to elucidate the relation between the controller output and applied voltage to the motor terminal, the place in which the fault might occur. The relation is derived based on the comparison of healthy and postfault operation of induction motor drives controlled in a field-oriented control (FOC) manner. Without any modification to the overall closed-loop controller structure, the fault is perceived as a disturbance to the system. Based on this approach, the lumped impact of the open-circuit fault (OCF) and topology reconfiguration is identified and compensated by injecting a suitable feedforward term. The effectiveness of the proposed fault-tolerant controller is verified and compared through the simulation and experiment, ensuring the smooth operation in postfault mode.