مجال التميز | تميز دراسي وبحثي |
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البحث (1): | |
عنوان البحث: |
A Novel PV Array Reconfiguration Algorithm Approach to Optimising Power Generation across Non-Uniformly Aged PV Arrays by Merely Repositioning |
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تاريخ النشر: |
11/02/2020 |
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Photovoltaic (PV) module working conditions lack consistency and PV array power outputs fluctuate due to the non-uniform impact that aging has on various PV modules in a PV array. No assessment has been conducted on the energy potential of a non-uniform PV array, despite the fact that the maximum power point (MPP) can be tracked by global maximum power point tracking (GMPPT). Therefore, the present work undertakes such an assessment by devising an algorithm to optimise the PV array electrical structure as the PV modules undergo aging in a non-uniform way. To enable PV arrays with non-uniform aging to produce as much power as possible and to make maintenance more cost-effective, the work puts forward a novel approach for reconfiguring PV arrays, where the PV modules are repositioned by retaining the aged PV modules. By this approach, the selection of the best reconfiguration topology necessitates the information on the electrical parameters associated with the PV modules in an array. Furthermore, the non-uniform aging of the PV modules can engender an incompatibility effect, which can be diminished in the proposed algorithm through iterative sorting of the modules in a hierarchical pattern. To determine how effective the method is for PV arrays with non-uniform aging and of different sizes, such as 3 × 4, 5 × 8 and 7 × 8 arrays, computer simulation and analysis have been conducted, with findings indicating that, irrespective of dimensions, PV arrays with non-uniform aging can have improved power yield. |
البحث (2): | |
عنوان البحث: |
Gene Evaluation Algorithm for Reconfiguration of Medium and Large Size Photovoltaic Arrays Exhibiting Non-Uniform Aging |
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تاريخ النشر: |
14/04/2020 |
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Aging is known to exert various non-uniform effects on photovoltaic (PV) modules within a PV array that consequently can result in non-uniform operational parameters affecting the individual PV modules, leading to a variable power output of the overall PV array. This study presents an algorithm for optimising the configuration of a PV array within which different PV modules are subject to non-uniform aging processes. The PV array reconfiguration approach suggests maximising power generation across non-uniformly aged PV arrays by merely repositioning, rather than replacing, the PV modules, thereby keeping maintenance costs to a minimum. Such a reconfiguration strategy demands data input on the PV module electrical parameters so that optimal reconfiguration arrangements can be selected. The algorithm repetitively sorts the PV modules according to a hierarchical pattern to minimise the impact of module mismatch arising due to non-uniform aging of panels across the array. Computer modelling and analysis have been performed to assess the efficacy of the suggested approach for a variety of dimensions of randomly non-uniformly aged PV arrays (e.g., 5 × 5 and 7 × 20 PV arrays) using MATLAB. The results demonstrate that enhanced power output is possible from a non-uniformly aged PV array and that this can be applied to a PV array of any size. |
البحث (3): | |
عنوان البحث: |
Investigating Fourteen Countries to Maximum the Economy Benefit by Using Offline Reconfiguration for Medium Scale PV Array Arrangements |
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تاريخ النشر: |
24/12/2020 |
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Over the past few years, electricity demand has been on the rise. This has resulted in renewable energy resources being used rapidly, considering the shortage as well as the environmental impacts of fossil fuel. A renewable energy source that has become increasingly popular is photovoltaic (PV) energy as it is environmentally friendly. Installing PV modules, however, has to ensure harsh environments including temperature, dust, birds drop, hotspot, and storm. Thus, the phenomena of the non-uniform aging of PV modules has become unavoidable, negatively affecting the performance of PV plants, particularly during the middle and latter duration of their service life. The idea here is to decrease the capital of maintenance and operation costs involved in medium- and large-scale PV power plants and improving the power efficiency. Hence, the present paper generated an offline PV module reconfiguration strategy considering the non-uniform aging PV array to ensure that this effect is mitigated and does not need extra sensors. To enhance the economic benefit, the offline reconfiguration takes into account labor cost and electricity price. This paper proposes a gene evolution algorithm (GEA) for determining the highest economic benefit. The proposed algorithm was verified using MATLAB software-based modeling and simulations to investigate fourteen countries to maximize the economic benefit that employed a representative 18-kW and 43-kW output and the power of 10 × 10 PV arrays in connection as a testing benchmark and considered the electricity price and workforce cost. According to the results, enhanced power output can be generated from a non-uniformly aged PV array of any size, and offers the minimum swapping/replacing times to maximize the output power and improve the electric revenue by reducing the maintenance costs. |
البحث (4): | |
عنوان البحث: |
An Experimental Investigation on Output Power Enhancement With Offline Reconfiguration for Non-Uniform Aging Photovoltaic Array to Maximise Economic Benefit |
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تاريخ النشر: |
11 June 2021 |
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There are several non-uniform effects on photovoltaic (PV) modules related to aging in a PV array. These subsequently bring about non-uniform operating parameters with individual PV modules, causing a variance in the PV array performance. The current study undertakes an indoor experimental study to establish and positively affect the efficacy of a non-uniform aged 2 ×4 PV array, with a commercially available small panel module of 0.36W (monocrystalline). This paper proposes a gene evolution algorithm (GEA) for offline reconfiguration that can provide more significant output power compared to non-uniformly aged PV arrays through repositioning instead of replacing aged PV modules, which will help lower maintenance expenses. This reconfiguration requires data input from the PV module’s electrical properties in order to select ideal reconfiguration setups. The outcomes show that greater output power can be facilitated through a non-uniformly aged PV array and used on many different PV array sizes. |
البحث (5): | |
عنوان البحث: |
Cost Effective Offline Reconfiguration for Large-Scale Non-Uniformly Aging Photovoltaic Arrays Efficiency Enhancement |
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تاريخ النشر: |
28/04/2020 |
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In the past decades, a huge number of large-scale photovoltaic (PV) plants have been constructed all around the world. However, the capital and operational costs can be high, which limits their widespread applications. Because the installed PV modules often operate in harsh environments (i.e. storm, high temperature, dust, hail, etc.), non-uniform aging phenomena of PV modules cannot be avoided and it impacts adversely on the performance of PV plants, especially in the middle and late periods of their service life. This paper develops an offline PV module reconfiguration strategy for the non-uniform aging PV array to mitigate this effect. In order to maximize the economic benefit, electricity price and labor cost are considered in the offline reconfiguration. The Branch-and-Bound based optimization algorithm is proposed to find the highest economic benefit. In order to verify the proposed algorithm, MATLAB software-based modelling and simulation have been performed in four case studies, in which a typical 42kW PV array with 7 × 20 connection is employed in a testing benchmark, and the manpower cost and electricity price in USA, UK, China and Turkey are considered in the case study. The results demonstrate that the economic benefit from a non-uniformly aged PV array is further enhanced with the proposed reconfiguration method. |
البحث (6): | |
عنوان البحث: |
Design and Analysis of a Novel Converter Topology for Photovoltaic Pumps Based on Switched Reluctance Motor |
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تاريخ النشر: |
01/07/2019 |
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In order to improve the performance of switched reluctance motor (SRM) systems for photovoltaic (PV) pumps, this paper introduces a new converter topology for SRM with controllable multiple power sources. Only simple switching components need to be added at the front end of the asymmetric half-bridge converter in this topology, which enables the control of multiple power sources. The new PV pump system has four operating modes, which are the PV panel driven mode, battery bank driven mode, dual-source driven mode, and battery charging mode. By adjusting the state of the front-end converter switch, the voltage tracking of PV panel can be achieved, providing a stable bus voltage for the SRM system. By controlling the battery bypass switch, the bus voltage of SRM system can be increased, thereby increasing the system power level. Simulations and experiments based on a four-phase 8/6 SRM demonstrate the effect of the novel converter proposed in this paper. |
البحث (7): | |
عنوان البحث: |
An Innovative Near-Field Communication Security Based on the Chaos Generated by Memristive Circuits Adopted as Symmetrical Key |
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تاريخ النشر: |
09/09/2020 |
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The new technology solutions are playing an important role in the hardware security. One of the latest techniques is the use of the Memristor as an encryption element. In this paper, it has been introduced a two-column array inductor for Memristor-Based Wireless Power Transfer (M-WPT) systems. The traditional WPT circuits are based on switches, which do require a control circuit for timing and have low data encryption factor. By adopting the memristive Chua`s circuit with the chaotic behaviour characteristic, it is possible to create a symmetrical dual-key cryptography. Furthermore, in this innovative solution, the high inductance value of the traditional Chua circuit can be further reduced by using the dynamic effects of the coils flux linkage. The simulation results exhibit the dual-scroll attractors phase portrait, which is available for encryption features. Therefore, the data collected from the phase portrait are used as true random number generator in Python code. Instead of using algorithms, the code can create a symmetrical key for an unique chaotic cryptography. In order to build a prototype, it has been created a PCB design for the whole system. The experiment highlights the unpredictable voltage and current and validates the chaotic behaviour of the transmitter and receiver. |
البحث (8): | |
عنوان البحث: |
Time-Effective Dust Deposition Analysis of PV Modules Based on Finite Element Simulation for Candidate Site Determination |
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تاريخ النشر: |
02/04/2020 |
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For a photovoltaic (PV) power generation system, the shading effect of PV panels caused by dust deposition is extremely unfavorable. The deposition of dust results in a severe reduction of power generation output, since the efficiency of PV panels is affected by the shading irradiance and blocking the cooling. In this study, a numerical simulation method is proposed to model the dust accumulation on PV panels to detect the effects on PV power generation caused by different wind directions and wind speeds. Due to the high accuracy of numerical simulation, and the short calculation cycle, the proposed method provides a certain prediction for the soiling management of PV panels in the wind-sand environment. Through simulations and experiments, the impacts of dust accumulation on the performance of PV panels with different wind directions are studied in detail with the wind speed changing from 4.43 m/s to 6.48 m/s and the dust particle size of 10 μm to 100 μm, which are based on the environment of Liverpool, England in a year. Besides, for PV arrays, the turbulences of the dust distribution around the PV panels are also analyzed. The data collected from experiments and simulations are used to verify the effectiveness of the proposed strategy. |
البحث (9): | |
عنوان البحث: |
A Review of Methods and Challenges for Improvement in Efficiency and Distance for Wireless Power Transfer Applications |
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تاريخ النشر: |
10/10/2020 |
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Over the past few years, interest and research in wireless power transfer (WPT) have been rapidly incrementing, and as an effect, this is a remarkable technology in many electronic devices, electric vehicles and medical devices. However, most of the applications have been limited to very close distances because of efficiency concerns. Even though the inductive power transfer technique is becoming relatively mature, it has not shown near-field results more than a few metres away transmission. This review is focused on two fundamental aspects: the power efficiency and the transmission distance in WPT systems. Introducing the principles and the boundaries, scientific articles will be reviewed and discussed in terms of their methods and respective challenges. This paper also shows more important results in efficiency and distance obtained, clearly explaining the theory behind and obstacles to overcome. Furthermore, an overlook in other aspects and the latest research studies for this technology will be given. Moreover, new issues have been raised including safety and security. |
البحث (10): | |
عنوان البحث: |
Modeling, Analysis, and Attenuation of Uncontrolled Generation for IPMSM-Based Electric Vehicles in Emergency |
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تاريخ النشر: |
09/07/2019 |
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Inevitable faults such as overcurrent might occur when interior permanent magnet synchronous machines (IPMSM) with high constant-power speed ratio in electric vehicles rotate over high-speed range, causing uncontrolled generation (UCG) phenomenon. In the process, the large current might be generated and then flow back to the battery through the uncontrolled rectifier, posing a great risk to the power devices. For a better understanding of UCG, this paper first explains the transient process by establishing a dynamic model of the uncontrolled rectifier (UR). Then, aiming at the steady-state generating stage, an enhanced UCG model is proposed for the analysis of motor parameter dependencies. Because it is found that the maximum UCG feedback current at high speed is inversely proportional to the d-axis inductance, an inductance design/optimization method for appropriate d-axis by changing the rotor structure is developed to attenuate the side effect of UCG. The proposed UCG model and the validity of the design/optimization approach are verified by experiments. The results have proved that the new model can be employed to estimate the working state of an IPMSM drive system under UCG operation and determine the optimal motor parameters in the course of machine design and optimization. |
البحث (11): | |
عنوان البحث: |
Internal Voltage Phase-Amplitude Dynamic Analysis With Interface Friendly Back-To-Back Power Converter Average Model for Less Power Electronics-Based More-Electric Ship |
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تاريخ النشر: | 09/07/2019 |
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The advancement in power electronics techniques provides a strong impetus for the adoption of medium-voltage direct current (MVDC) shipboard power system (SPS). However, high fault protection difficulty and cost are the major challenges. In this paper, a partially power decoupled SPS based on the doubly fed induction machine (DFIM) propulsion load is presented to increase the system safety level by using less power electronics. Different from a grid-connected DFIM-based system, the on-board power of the proposed DFIM-SPS is supplied from standalone synchronous generators, and its system dynamics need to be further investigated. An interface friendly average model for the back-to-back power converter (BTBPC) in DFIM-SPS is proposed for system-level dynamic study, which reduces the simulation time and is easy for physical understanding. The stator and BTBPC of DFIM are regarded as separate voltage vectors in the system, and small-signal modeling is carried out in the electromechanical control timescale to analyze the internal voltage phase-amplitude dynamics. The control effects of rotor speed control (RSC), reactive power control (RPC), and phase-locked loop (PLL) are considered in the modeling process. The simulations are performed to study the control effects on DFIM-SPS in MATLAB/Simulink, with the effectiveness of the proposed BTBPC average model validated. |
البحث (12): | |
عنوان البحث: |
Modular Tri-Port Converter for Switched Reluctance Motor based Hybrid Electrical Vehicles |
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تاريخ النشر: |
24/01/2019 |
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Hybrid electrical vehicle (HEV) is a popular transport solution to reducing carbon dioxide emissions. Switched reluctance motors (SRMs) are one of the most promising motors for such applications. In SRM-based series-type HEV, there are three energy components, i.e., generator, battery bank, and SRM. A tri-port converter is needed to combine the three energy components in one power converter. The tri-port converter has a modular and concise structure, which meets the requirements for HEV applications. The proposed tri-port converter supports five working modes, including generator to SRM, battery bank to SRM, generator and battery bank to SRM, generator to SRM and battery bank, and battery bank to SRM and generator under driving conditions; under standstill conditions, generator to battery bank and battery bank to generator energy flow can also be realized without requiring extra converters. The corresponding control strategies are also developed to cooperate with different working modes. Moreover, the fault tolerance characteristics of the tri-port converter are investigated to expand its feasibility under harsh HEV application conditions. The simulation and experiments are undertaken with a 750W prototype to evaluate the performance of the proposed tri-port converter for HEV applications. |
البحث (13): | |
عنوان البحث: |
Carbon Footprint Modeling of a Clinical Lab |
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تاريخ النشر: |
09/11/2018 |
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Modeling of a clinical lab carbon footprint is performed in this study from the aspects of electricity, water, gas consumption and waste production from lab instruments. These environmental impact indicators can be expressed in the form of the CO2 equivalent. For each type of clinical test, the corresponding consumption of energy resources and the production of plastics and papers are taken into consideration. In addition, the basic lab infrastructures such as heating, ventilation, air-conditioning (HVAC) systems, lights, and computers also contribute to the environmental impact. Human comfort is to be taken into account when optimizing the operation of lab instruments, and is related to the operation of HVAC and lighting systems. The detailed modeling takes into consideration the types of clinical tests, operating times, and instrument specifications. Two ways of disposing waste are classified. Moreover, the indoor environment is modeled. A case study of the Biochrom 30+ amino acid analyzer physiological system in Alder Hey Children’s Hospital is carried out, and the methods of mitigating the overall environmental impacts are discussed. Furthermore, the influence of climate on the results is investigated by using the climate data in Liverpool and Athens in October. |
المؤتمرات العلمية |
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المؤتمر (1): | |
عنوان المؤتمر: |
IECON 2019 – 45th Annual Conference of the IEEE Industrial Electronics Society |
تاريخ الإنعقاد: |
14-17/10/2019 |
مكان الإنعقاد: |
Lisbon, Portugal |
طبيعة المشاركة: |
Oral presentation |
عنوان المشاركة: |
Analysis of Dust Deposition on PV Arrays by CFD Simulation |
ملخص المشاركة: |
This paper directly observe the impact of wind-sand factor on Photovoltaic (PV) panel. Taking into account the influence of this factor, based on the simulation of FLUENT, this paper simulates the situation of PV panels in the wind-sand two phases flow field. For a PV power generation system, sand and dust have the greatest impact, which not only block the PV panels, but also increase the temperature. Furthermore, it damage the surface of the panel, reducing its efficiency. The cleaning cycle of the PV panel is predicted by observing the accumulation of dust. |
الرابط: | |
المؤتمر (2): | |
عنوان المؤتمر: |
IECON 2019 – 45th Annual Conference of the IEEE Industrial Electronics Society |
تاريخ الإنعقاد: |
14-17/10/2019 |
مكان الإنعقاد: |
Lisbon, Portugal |
طبيعة المشاركة: |
Oral presentation |
عنوان المشاركة: |
Simulation Study of the Effects of Synchronous Generator Parameter Deviations on the Performance of a DFIM-SPS |
ملخص المشاركة: |
Targeting at reduce the difficulty of fault protection of a modern more-electric ship (MES), a doubly-fed induction motor (DFIM) based shipboard propulsion system (SPS) is proposed. The on-board electric power supply is provided by a synchronous generators (SG). Therefore, the accurate parameter setting is important for achieving the optimal system performance. In this paper, the effects of parameter deviations (PDs) in SG on the system performance are studied. The detailed models of a salient-pole SG and a type DC1A excitation system (EXS) are presented. Different degrees of PDs (DoPDs) are applied to 8 important parameters of SG to analyze the sensitivity of each parameter. Simulation studies are carried out in Matlab/Simulink to obtain data for investigating the PD effects. Three PD effect indicators (PDEIs) are defined to illustrate the effects on the SG terminal voltage and output active power. Meanwhile, when applying different DoPDs, the increasing rates of PDEIs are different, which are also investigated. Moreover, the two most critical SG parameters are determined, and the overall system performance is analyzed when applying different DoPDs on these two parameters. |
الرابط: | |
المؤتمر (3): | |
عنوان المؤتمر: |
IECON 2019 – 45th Annual Conference of the IEEE Industrial Electronics Society |
تاريخ الإنعقاد: |
14-17/10/2019 |
مكان الإنعقاد: |
Lisbon, Portugal |
طبيعة المشاركة: |
Oral presentation |
عنوان المشاركة: |
Control of Doubly-Fed Induction Motor Based Shipboard Propulsion System for More-Electric Ships |
ملخص المشاركة: |
In this paper, a doubly-fed induction motor (DFIM) based shipboard propulsion system (SPS) is proposed for more-electric ships (MESs). Two power flow paths are presented, which are based on direct AC power transmission and power decoupling with back-to-back converter (BTBC). This type of SPS minimizes unnecessary power conversion and increases the system robustness to power converter faults. The synchronous generator (SG) and DFIM are the main power components in the proposed DFIM-SPS. An emulated stator voltage orientated vector control (ESVO-VC) strategy without using phase-locked loop (PLL) is proposed. The simulation study is carried out in Matlab/Simulink to verify the performance of the proposed DFIM-SPS, with frequent load variations taken into consideration. By employing the proposed ESVO-VC scheme, high quality of input three-phase currents, high power factor, and superior torque tracking performance are presented. Furthermore, a control-hardware-in-the-loop (CHIL) setup is used to implement the proposed ESVO-VC with the power circuits of SG and BTBC simulated in a realtime digital simulator (RTDS) to verify the system control performance in the almost practical environment. |
الرابط: | |
المؤتمر (4): | |
عنوان المؤتمر: |
2020 IEEE Applied Power Electronics Conference and Exposition (APEC) |
تاريخ الإنعقاد: |
15-19 March 2020 |
مكان الإنعقاد: |
New Orleans, LA, USA |
طبيعة المشاركة: |
Oral presentation |
عنوان المشاركة: |
FCS Model Predictive Current Control Method for EV PMSMs at Low Control Frequency Considering Flux Mismatch |
ملخص المشاركة: |
In order to improve the control performance of the permanent magnet synchronous machine (PMSM) drives in electric vehicles, this paper proposes a novel finite control set (FCS) model predictive current control (MPCC) method to reduce the adverse impacts caused by the low control frequency (LCF) and flux linkage mismatch (FLM). Firstly, the disadvantages of the traditional FCS-MPCC methods are illustrated in detail. Then, aiming at the LCF problem, the implementation of the FCS-MPCC algorithm based on tripartite predictions but single actuation is specially designed. In terms of the FLM issue, this paper develops a direct handling strategy by using the parameter identification technology. In detail, a stable sliding mode flux linkage (SM-FL) observer is designed to detect the realtime flux linkage. Finally, the simulation results prove that the proposed FCS-MPCC algorithm is effective. |
الرابط: |
محمد سعيد عبدالله القحطاني
دكتوراه
هندسة
University of Liverpool