Papers by Phúc Huân Huỳnh
“Enabling circular business models in the fashion industry: the role of digital innovation”
International Journal of Productivity and Performance Management, Jun 8, 2021
PurposeDigital innovation and circular business model innovation are two critical enablers of a c... more PurposeDigital innovation and circular business model innovation are two critical enablers of a circular economy. A wide variety of digital technologies such as blockchain, 3D printing, cyber-physical systems, or big data also diverges the applications of digital technologies in circular business models. Given heterogeneous attributes of circular business models and digital technologies, the selections of digital technologies and circular business models might be highly distinctive within and between sectorial contexts. This paper examines digital circular business models in the context of the fashion industry and its multiple actors. This industry as the world’s second polluting industry requires an urgent circular economy (CE) transition with less resource consumption, lower waste emissions and a more stable economy.Design/methodology/approachAn inductive, exploratory multiple-case study method is employed to investigate the ten cases of different sized fashion companies (i.e. large, small medium-sized firm (SME) and startup firms). The comparison across cases is conducted to understand fashion firms' distinct behaviours in adopting various digital circular economy strategies.FindingsThe paper presents three archetypes of digital-based circular business models in the fashion industry: the blockchain-based supply chain model, the service-based model and the pull demand-driven model. Besides incremental innovations, the radical business model and digital innovations as presented in the pull demand-driven model may be crucial to the fashion circular economy transition. The pull demand–driven model may shift the economy from scales to scopes, change the whole process of how the fashion items are forecasted, produced, and used, and reform consumer behaviours. The paths of adopting digital fashion circular business models are also different among large, SMEs and startup fashion firms.Practical implicationsThe study provides business managers with empirical insights on how circular business models (CBMs) should be chosen according to intrinsic business capacities, technological competences and CE strategies. The emerging trends of new fashion markets (e.g. rental, subscription) and consumers' sustainable awareness should be not be neglected. Moreover, besides adopting recycling and reuse strategies, large fashion incumbents consider collaborating with other technology suppliers and startup companies to incubate more radical innovations.Social implicationsAppropriate policies and regulations should be enacted to enable the digital CE transition. Market patterns and consumer acceptances are considered highly challenging to these digital fashion models. A balanced policy on both the demand and supply sides are suggested. The one-side policy may fail CBMs that entail an upside-down collaboration of both producers and consumers. Moreover, it is perhaps time to rethink how to reduce unnecessary new demand rather than repeatedly producing and recycling.Originality/valueThe pace of CE research is lagging far behind the accelerating environmental contamination by the fashion industry. The study aims to narrow the gap between theory and practice to harmonise fashion firms' orchestration and accelerate the transition of the fashion industry towards the CE. This study examines diverse types of digital technologies in different circular business models in a homogeneous context of the fashion industry with heterogeneous firm types.
High-speed rarefied gas flow simulations using Quasi-Gas Dynamic equations with slip and jump boundary conditions
Proceedings Of The Institution Of Mechanical Engineers, Part G: Journal Of Aerospace Engineering, May 27, 2022
Design and Optimization of an Integrated Generator-Rectifier System for Offshore Wind Turbines
2021 IEEE International Electric Machines & Drives Conference (IEMDC)
Many modern direct-drive wind generators at high power levels adopt permanent magnet synchronous ... more Many modern direct-drive wind generators at high power levels adopt permanent magnet synchronous generators (PMSGs). Typically, these PMSGs are coupled with fully rated active rectifiers to process and deliver power to the main grid. However, the limited-speed nature of a wind turbine creates an opportunity to reduce the amount of active rectification required, which in turn would reduce the cost of the drive and improve system reliability. This paper presents a design and optimization process of a direct-drive PMSG coupled to an integrated generator-rectifier system. In order to make the hybrid architecture possible, a multi-port generator is designed with multiple diode rectifiers and a single active rectifier. This paper describes a process for a 10 MW generator-drive optimization under the proposed architecture with two different implementation methods. These implementations are compared using optimal Pareto front from a system-level efficiency-weight perspective.
2020 IEEE Energy Conversion Congress and Exposition (ECCE), 2020
Harvesting offshore wind energy conventionally relies on multi-megawatt direct-drive permanent-ma... more Harvesting offshore wind energy conventionally relies on multi-megawatt direct-drive permanent-magnet synchronous generators equipped with full-power-rated active rectifiers. Functional integration of the generator and rectifier has led to the creation of an integrated generator-rectifier system with higher efficiency, reliability and power density. In this architecture, power electronics weight and efficiency depend on the generator inductance, while at the same time, the generator design must be optimized for weight and efficiency to realize the potential system-level benefits. This paper proposes a framework using the generator per-unit reactance as a handshake variable to co-design the generator and power electronics. The design approach enables the reduction of the system weight and conversion losses by 25% and 61%, respectively, for a 10-MW system. Using conservative assumptions, economic and reliability assessments show a 4.5% increase in annual energy production, a 9x reduction in long-term failure rate, and a 6.5% decrease in levelized cost of electricity.
International Journal of Emerging Technologies in Learning (iJET), 2022
Machine learning has globally become a trend in most educational settings. This study aims to exp... more Machine learning has globally become a trend in most educational settings. This study aims to explore students’ perceptions when using Google Translate (GT) to support their learning as well as their problems and solutions from GT. With the participation of 250 university students at a private educational institution, a 5-point Likert-scale questionnaire and a semi-structured interview were employed to examine how students perceived the use of GT in their learning process. The findings revealed that practically students had positive perceptions on GT’s use in learning. Several major problems were recorded when they used GT, and some recommended solutions were also considered for improvement. Specifically, students utilized GT as a learning tool, particularly for language study, because of its useful features such as multi-language translation, time saving, ease of use, and improving pronunciation. Although Google Translate has a number of advantages for students, several problems su...
2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019
An integrated generator-rectifier system can produce high conversion efficiency and reduce the si... more An integrated generator-rectifier system can produce high conversion efficiency and reduce the size of the active rectifier in high-power ac-to-dc conversion. A major disadvantage of this system is the use of bulky filter capacitors with passive rectifiers to obtain a low voltage-ripple dc bus. These filters are the main contributor to the overall system size, weight, cost, and failure, as well as to the low power factor at the ac ports powering the passive rectifiers. This paper presents an alternative approach: integrating the function of the filter elements into the active rectifier. A voltage opposite the passiverectifier ripple component is synthesized at the active-rectifier dcside by modulating the ac-side current. Compensation occurs due to the series connection of the rectifier dc outputs. In addition, an overall control architecture is proposed to use the active rectifier both as a filter element and a dc-bus voltage regulator. Simulation on a 3-MW, 4.9-kV dc system shows the total dcbus-voltage ripple factor is reduced by 57%, while the power factor at the passive-rectifier ac sides is 0.95. The proposed control architecture achieves regulation of the dc-bus voltage at variable dc-bus current and variable generator speed conditions. Experimental results corroborate the findings. Index Terms-Power conversion, ac-dc power conversion, rectifiers, dc power systems NOMENCLATURE x time-domain variable X average value/ dc component of x x small signal/ perturbation/ ac component of x x * / X * reference value of x/ X X(s) Laplace domain representation of x
Commercialising circular economy innovations: a taxonomy of academic spin-offs
Academy of Management Proceedings, 2021
Sự hiện diện của nguồn phân tán DG (Distributed Generator) đã gây ra những thách thức đến việc du... more Sự hiện diện của nguồn phân tán DG (Distributed Generator) đã gây ra những thách thức đến việc duy trì độ tin cậy của những OCPR quá dòng OCPR (Over-current Protection Relay) khi hoạt động để bảo vệ lưới điện phân phối (LĐPP). Trong quá trình vận hành để đảm bảo cung cấp điện cho LĐPP, những đặc tính vận hành của nguồn DG đã làm thay đổi đáng kể giá trị dòng điện sự cố và đây là nguyên nhân chính dẫn đến những hiện tượng OCPR hoạt động không tin cậy, chẳng hạn như mất tính chọn lọc, giảm độ nhạy, hoạt động vượt cấp hoặc hoạt động đồng thời. Do đó, việc điều phối những OCPR thuộc hệ thống bảo vệ trên LĐPP có xem xét đến những đặc tính vận hành của nguồn DG nhằm đảm bảo tính phối hợp khi hoạt động là cần thiết. Trong nghiên cứu này, nhóm tác giả sẽ giới thiệu về một phương pháp điều phối bảo vệ OCPCO (Over-current Protection Coordination Optimization) dành cho hệ thống bảo vệ của LĐPP có tích hợp nguồn DG. Cụ thể, phương pháp OCPCO này được phát triển dựa vào việc sử dụng kết quả phân...
Generator Back-Electromotive-Force Shaping for DC Output with Low Ripple Voltage
2019 IEEE International Electric Machines & Drives Conference (IEMDC), 2019
An integrated generator-rectifier system has been shown to be beneficial in reducing ac-to-dc con... more An integrated generator-rectifier system has been shown to be beneficial in reducing ac-to-dc conversion loss at megawatt power level. The architecture incorporates passive and active rectifiers into a multi-port permanent magnet synchronous generator. With a conventional sinusoidal back emf, filter capacitors are required on passive rectifiers to create a low-ripple-voltage dc bus. These capacitors are bulky, unreliable, and reduce the power factor on the ac ports. Consequently, the generator must be over designed to accommodate high peak ac current. This paper proposes an alternative back emf shape, relying on the trapezoidal waveform. The proposed back emf accomplishes debus ripple voltage of less than 5% at a high power factor using a capacitor-less passive rectifier. In addition, the generator torque ripple is reduced compared to a sinusoidal-back-emf machine. This opens an opportunity for compact generator design while further reducing the power electronics size, weight, and cost. The relationship between the dc-bus ripple voltage and the trapezoidal back emf is developed analytically. The findings are used to shape the generator back emf and select the range of the synchronous inductance. Simulation and experimental results corroborate the proposed approach.
Integrated Generator-Rectifier for Electric Ship DC Power System
2019 IEEE Electric Ship Technologies Symposium (ESTS), 2019
Future ships are envisioned to be electric with a medium-voltage dc grid feeding all the subsyste... more Future ships are envisioned to be electric with a medium-voltage dc grid feeding all the subsystems, including propulsion, weapons, and auxiliary loads. Gas-turbine driven ac generators are prominent candidates for shipboard electricity generation due to a high energy density. Consequently, megawatt-class ac-to-dc conversion systems are essential to make electric ships feasible. At medium-voltage and megawatt power, conventional ac-to-dc conversion systems are challenged by limited power electronics switch-voltage ratings, high conversion loss, convoluted circuitry, and complex control schemes. An integrated generator-rectifier system has been proposed as an alternative that employs low-voltage switches to form a medium-voltage dc bus. Low conversion losses and high system reliability are achieved by shifting power to the efficient passive rectifiers. This paper presents an integrated design in context of shipboard power system. Theoretical analyses show the size of the active rectifier is reduced by 37% and the total conversion loss is cut by 50A laboratory setup is established to corroborate the proposed system.
IEEE Transactions on Power Electronics, 2021
An integrated generator-rectifier system is a promising architecture to harvest energy in offshor... more An integrated generator-rectifier system is a promising architecture to harvest energy in offshore wind turbines. The system processes the majority of the incoming power using reliable, efficient, and inexpensive passive diodes operating at the generator line frequency. Elimination of capacitors at the diode rectifiers' output by appropriately phase shifting the voltages of a multiport generator further improves the reliability of the overall architecture. This article creates a generalized framework to evaluate the interactions among different generator ports, diode-bridge rectifiers, and the active rectifier that is used to control the power flow. The framework enables quantifying the effect of integration on the dc bus power ripple and power imbalance among different generator ports. An exemplary winding layout is proposed that ensures theoretically zero interaction between the passive ports, although all the ports are mounted on a magnetic structure. A 10-MW integrated generator-rectifier design and simulation proves the accuracy of the framework using coupled circuit and finite-element simulation. Finally, a laboratory prototype shows the realization of the winding layout. The proposed inductance-matrixbased framework can be used to evaluate other winding layouts to estimate the effect of magnetic coupling on the performance of the system. Index Terms-AC-DC power conversion, dc power systems, generators, permanent magnet machines, power conversion, rectifiers, wind energy, wind energy generation. I. INTRODUCTION O FFSHORE wind is an emerging renewable energy resource with rapidly increasing installed capacity [1]-[4]. Direct-drive permanent-magnet synchronous generators (PMSGs) with full power converters have been the preferred choice for energy harvesting [5]-[10]. For example, Gamesa 10X, GE Haliade X, and Vestas V164, rated between 10 and 14 MW, adopt this architecture [11]-[13]. In contrast, an integrated generator-rectifier architecture reduces the amount of power processed by the active rectifier by
Tạp chí Y học Việt Nam, 2021
Mục tiêu: Xác định giá trị của cộng hưởng từ trong đánh giá xâm lấn diện cắt chu vi đối chiếu với... more Mục tiêu: Xác định giá trị của cộng hưởng từ trong đánh giá xâm lấn diện cắt chu vi đối chiếu với kết quả giải phẫu bệnh & Nhận xét mối liên quan của một số yếu tố với tình trạng diện cắt chu vi. Phương pháp: Mô tả cắt ngang tiến cứu. Kết quả: Độ nhaỵ, độ đặc hiệu, độ chính xác: cộng hưởng từ trong đánh giá xâm lấn diện cắt chu vi đối chiếu với kết quả giải phẫu bệnh lần lượt là: 33,3% (95% CI: 4,3 – 77,7%); 93,7% (95% CI: 84,5 – 98,2%) và 88,4% (95% CI: 78,4 – 94,9%). Ghi nhận các yếu tố: vị trí khối u (p<0,05); xâm lấn thành ruột (T) trên cộng hưởng từ (p<0,001) và đường kính khối u (p<0,001); di căn hạch (N) (p<0,01); xâm lấn quanh thần kinh (p<0,05) ở giải phẫu bệnh có mối liên quan với tình trạng diện cắt chu vi (sự khác biệt có ý nghĩa thống kê). Kết luận: Độ đặc hiệu và độ chính xác của cộng hưởng từ trong đánh giá xâm lấn diện cắt chu vi khá cao; tuy nhiên độ nhạy còn thấp. Các yếu tố nguy cơ liên quan với tình trạng diện cắt chu vi là: vị trí, đường kính khối...
Slotless-PM Machine Design for an Integrated Generator-Rectifier Architecture for Off-Shore Wind Turbines
IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021
Integrated generator-rectifier architecture has been shown to substantially improve power density... more Integrated generator-rectifier architecture has been shown to substantially improve power density, efficiency, and reliability of the electric drivetrains in wind turbines. From a power-electronic perspective, the architecture processes a majority share of the incoming power through passive diodes operating at the generator’s fundamental frequency. This article presents a design methodology of a 10-MW generator, which involves a specific low-reactance generator to minimize the commutation voltage drop at the passive rectifiers as well as prevent power imbalance between different generator ports. Appropriate phase shifts between the multiple passive ports to eliminate the need for a dc-link capacitor improve the drivetrain reliability. The proposed design adopts a slotless permanent magnet (PM) generator, where the reactance is greatly constrained by eliminating the stator slots. In addition, a Halbach PM-array structure reduces the reactance by removing the rotor back iron. The design methodology uses these features along with a multiobjective optimization framework to maximize power density and efficiency while retaining a low reactance. Co-simulation of the generator and integrated power electronics shows that the proposed architecture is suitable for off-shore wind generators. Finally, a subscale generator is tested to verify the low-reactance design of the proposed generator.
Science & Technology Development Journal - Engineering and Technology, 2020
The penetration of distributed generators (DG ) into the distribution etworks (DN) greatly improv... more The penetration of distributed generators (DG ) into the distribution etworks (DN) greatly improves the reliability of electricity supply and reduces power loss. However, the operation of these DGs can also make the protection of distribution etwork more complex. This paper will examine the effects of two DG types on the protection of DN by analyzing the solution called Fault Location, Isolation and Service Restoration (FLISR). The FLISR approach considers DGs as auxiliary sources for the post-fault restoration plans in order to minimize the number of interrupted customers and unserved energy. Moreover, the combination of setting value of the overcurrent relay and the statuses of switching device and the loss voltage warning signal are used to detect and identify types of incidents in the distribution etwork with DGs. A two-constrained objective function will be solved to find possible plans for fault isolation and service restoration. There are six performance indices (PIs) selecte...
IEEE Transactions on Power Electronics, 2021
Offshore wind is a rapidly growing renewable energy resource. Harvesting offshore energy requires... more Offshore wind is a rapidly growing renewable energy resource. Harvesting offshore energy requires multimegawatt wind turbines and high efficiency, high power density, and reliable power conversion systems to achieve a competitive levelized cost of electricity. An integrated system utilizing one active and multiple passive rectifiers with a multiport permanent magnet synchronous generator is a promising alternative for an electromechanical power conversion system. Deployment of the integrated systems in offshore wind energy requires maximum power point tracking (MPPT) capability, which is challenging due to the presence of numerous uncontrolled passive rectifiers. This article shows feasibility of MPPT based on a finding that the active-rectifier d-axis current can control the total system output power. The MPPT capability opens up opportunities for the integrated systems in offshore wind applications. Index Terms-AC-DC power conversion, dc power systems, maximum power point trackers (MPPT), power conversion, rectifiers, wind energy, wind energy generation. I. INTRODUCTION O FFSHORE wind is an emerging renewable energy resource with rapidly increasing installed capacity [2]-[5]. Recently, offshore wind turbines exceeding the common landbased power output have been developed to target a competitive levelized cost of electricity (LCOE). For example, Gamesa 10X [6], Haliade X [7], and Vestas V164 [8] have power ratings ranging between 10 and 12 MW. Development of highpower-density, efficient, and reliable electromechanical power conversion systems for these turbines based on conventional converter topologies is challenging. The major obstacles are limited power-electronics-switch voltage/current ratings and high switching losses [9]. Two-level pulsewidth modulation (PWM) and neutral-point-clamped converters are the most commonly used architectures. The former has a simple construction and a Manuscript
Science & Technology Development Journal - Engineering and Technology, 2020
Nowadays, distributed generators in Microgrids (MG) are developed to exploit the clean and renewa... more Nowadays, distributed generators in Microgrids (MG) are developed to exploit the clean and renewable energy from nature, such as solar irradiation, wind power, tidal wave, etc. Accordingly, an Aggregate Battery Energy Storage System (ABESS) is implemented to achieve the stability and reliability of MG. To be clearly decribed, the ABESS will play a main role as a power controller in supply-demand operation of MG. In order to demonstrate significance and importance of ABESS in the MG, its operation reliability will be introduced in this paper. The authors will use an analytical methodology based on Markov models to assess the operation reliability of the whole ABESS under dynamic operation cases. According to dynamic operation cases of MG with the ABESS and Photovoltaic Generation System (PVS), the failure rate of the ABESS is different. Simulations and test results are presented and discussed to prove that the operation reliability of the ABESS in the MG significantly depends on diff...
Science & Technology Development Journal - Economics - Law and Management, 2017
E–payment is an important component of e–commerce, it helps improving service quality and increas... more E–payment is an important component of e–commerce, it helps improving service quality and increasing user satisfaction of the e–commerce in the digital era. This study proposes and tests a model of e–payment adoption. Data is collected from e–commerce customers who have used or intend to use e–payment systems in Ho Chi Minh city. A survey study with the SEM analysis of 200 participants, six out of nine hypotheses are supported. Research results demonstrate that there are linear relationships between service quality, social influence, easy to use, and e–payment adoption. The research model illuminates roughly 51% of the e–payment adoption.
IEEE Transactions on Power Electronics, 2019
Conventional high-power ac-dc conversion architectures rely heavily on active rectifiers, which c... more Conventional high-power ac-dc conversion architectures rely heavily on active rectifiers, which consist of fully controlled power-electronic switches. These make the system bulky, lossy, and less reliable. This article presents an alternative approach-integrating a multiport permanent-magnet synchronous generator (PMSG) with series-stacked power converters. An active rectifier processes only a fraction of the total converted power while regulating the dc bus. The remaining power is processed by diode bridges, which allows a substantial increase in overall efficiency, power density, and reliability. Theoretical analysis shows that for wind-power generation applications, the active rectifier processes a maximum of 39% of the rated power while the generator operates in a speed range similar to the conventional doubly fed induction machine. The conversion loss is reduced by 47%. Results from a laboratory-scale experimental setup corroborate the proposed architecture. This approach potentially increases integration of medium-voltage dc distribution to the megawattclass mechanical-to-electrical energy conversion systems to achieve higher efficiency, higher power density, and lower cost compared to the conventional solutions based on a single-port PMSG with a full-power-rated converter.
IEEE Transactions on Power Systems, 2018
With the wide deployment of synchrophasor technology, measurement-based dynamic modeling and stud... more With the wide deployment of synchrophasor technology, measurement-based dynamic modeling and studies have been becoming increasingly useful for real-time grid operations. This paper considers the problem of estimating the power system frequency response from ambient synchrophasor measurements. Specifically, we develop the analytical conditions for establishing the equivalence between the cross-correlation of ambient generator speed data and the system frequency response between any two locations. Our conditions, relying on uniformly damped and equally excited oscillation modes, extend earlier work on electro-mechanical wave propagation modeling to nonhomogeneous power networks. Numerical results suggest that the validity of the cross-correlation approach would hold for more realistic conditions such as non-uniform damping and high-order generator model. Its practical value is further corroborated by real data results, which closely match with the actual propagation time of electromechanical waves recorded during the 2008 Florida blackout in the Eastern Interconnection system.
Economies, 2017
Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch ge... more Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in EconStor may be saved and copied for your personal and scholarly purposes. You are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public.
Uploads
Papers by Phúc Huân Huỳnh