Records with Subject: Process Operations
Showing records 1 to 25 of 41. [First] Page: 1 2 Last
An Event-Based Resource Management Framework for Distributed Decision-Making in Decentralized Virtual Power Plants
Jianchao Zhang, Boon-Chong Seet, Tek Tjing Lie
January 7, 2019 (v1)
Keywords: distributed decision-making, resource management framework, smart grid, virtual power plant
The Smart Grid incorporates advanced information and communication technologies (ICTs) in power systems, and is characterized by high penetration of distributed energy resources (DERs). Whether it is the nation-wide power grid or a single residential building, the energy management involves different types of resources that often depend on and influence each other. The concept of virtual power plant (VPP) has been proposed to represent the aggregation of energy resources in the electricity market, and distributed decision-making (DDM) plays a vital role in VPP due to its complex nature. This paper proposes a framework for managing different resource types of relevance to energy management for decentralized VPP. The framework views VPP as a hierarchical structure and abstracts energy consumption/generation as contractual resources, i.e., contractual offerings to curtail load/supply energy, from third party VPP participants for DDM. The proposed resource models, event-based approach to d... [more]
A Novel Method to Magnetic Flux Linkage Optimization of Direct-Driven Surface-Mounted Permanent Magnet Synchronous Generator Based on Nonlinear Dynamic Analysis
Qian Xie, Yanbin Zhang, Yanan Yu, Gangquan Si, Ningning Yang, Longfei Luo
January 7, 2019 (v1)
Keywords: compact representation, D-SPMSG, finite element analysis (FEA), magnetic flux linkage optimization, nonlinear dynamics
This paper pays attention to magnetic flux linkage optimization of a direct-driven surface-mounted permanent magnet synchronous generator (D-SPMSG). A new compact representation of the D-SPMSG nonlinear dynamic differential equations to reduce system parameters is established. Furthermore, the nonlinear dynamic characteristics of new D-SPMSG equations in the process of varying magnetic flux linkage are considered, which are illustrated by Lyapunov exponent spectrums, phase orbits, Poincaré maps, time waveforms and bifurcation diagrams, and the magnetic flux linkage stable region of D-SPMSG is acquired concurrently. Based on the above modeling and analyses, a novel method of magnetic flux linkage optimization is presented. In addition, a 2 MW D-SPMSG 2D/3D model is designed by ANSYS software according to the practical design requirements. Finally, five cases of D-SPMSG models with different magnetic flux linkages are simulated by using the finite element analysis (FEA) method. The nepho... [more]
Part-Load Performance Prediction and Operation Strategy Design of Organic Rankine Cycles with a Medium Cycle Used for Recovering Waste Heat from Gaseous Fuel Engines
Xuan Wang, Hua Tian, Gequn Shu
January 7, 2019 (v1)
Keywords: dynamic model, gaseous fuel engines, operation strategy, ORC, part-load, waste heat recovery
The Organic Rankine Cycle (ORC) is regarded as a suitable way to recover waste heat from gaseous fuel internal combustion engines. As waste heat recovery systems (WHRS) have always been designed based on rated working conditions, while engines often work under part-load conditions, it is quite significant to analyze the part-load performance and corresponding operation strategy of ORC systems. This paper presents a dynamic model of ORC with a medium cycle used for a large gaseous fuel engine and analyzes the effect of adjustable parameters on the system performance, giving effective control directions under various conditions. The results indicate that the intermediary fluid mass flow rate has nearly no effect on the output power and thermal efficiency of the ORC, while the mass flow rate of working fluid has a great effect on them. In order to get a better system performance under different working conditions, the system should be operated with the working fluid mass flow rate as larg... [more]
Greening the NetFPGA Reference Router
Feng Guo, Xiaojun Wang, Mei Song, Yifei Wei, Olga Ormond, Martin Collier
January 7, 2019 (v1)
Keywords: dynamic frequency scaling, energy proportional routing, green networking
Energy efficiency is an important criterion in the design of next generation networks for both economic and environmental concerns. This paper presents an energy-efficient router that is able to dynamically adapt its routing capability in response to real-time traffic load, achieving energy proportional routing. The NetFPGA reference router, which operates at one of two frequencies (125 MHz or 62.5 MHz), requires a board reset to switch frequencies. We have modified the reference router to allow dynamic switching among five operating frequencies. Experiments with real traces indicate that, compared to the reference router, a 10% power reduction can be achieved through dynamic frequency scaling. When the router is further modified to support green traffic engineering and Ethernet port shut-down, power consumption can be reduced by 46% while maintaining the required quality of service. This allows the router to meet the instantaneous performance requirements while minimizing power dissip... [more]
Implementation and Validation of a Self-Consumption Maximization Energy Management Strategy in a Vanadium Redox Flow BIPV Demonstrator
Luis Fialho, Tomás Fartaria, Luis Narvarte, Manuel Collares Pereira
January 7, 2019 (v1)
Keywords: building integrated photovoltaics (BIPV), energy management strategy, real-scale battery, self-consumption maximization, vanadium redox flow battery
This paper presents the results of the implementation of a self-consumption maximization strategy tested in a real-scale Vanadium Redox Flow Battery (VRFB) (5 kW, 60 kWh) and Building Integrated Photovoltaics (BIPV) demonstrator (6.74 kWp). The tested energy management strategy aims to maximize the consumption of energy generated by a BIPV system through the usage of a battery. Whenever possible, the residual load is either stored in the battery to be used later or is supplied by the energy stored previously. The strategy was tested over seven days in a real-scale VRF battery to assess the validity of this battery to implement BIPV-focused energy management strategies. The results show that it was possible to obtain a self-consumption ratio of 100.0%, and that 75.6% of the energy consumed was provided by PV power. The VRFB was able to perform the strategy, although it was noticed that the available power (either to charge or discharge) varied with the state of charge.
Frequency-Splitting-Free Synchronous Tuning of Close-Coupling Self-Oscillating Wireless Power Transfer
Po Hu, Jieshuai Ren, Wenan Li
December 3, 2018 (v1)
Keywords: close coupling, frequency-splitting, Hamel locus, self-oscillation, synchronous tuning, wireless power transfer (WPT)
The synchronous tuning of the self-oscillating wireless power transfer (WPT) in a close-coupling condition is studied in this paper. The Hamel locus is applied to predict the self-oscillating points in the WPT system. In order to make the system operate stably at the most efficient point, which is the middle resonant point when there are middle resonant and split frequency points caused by frequency-splitting, the receiver (RX) rather than the transmitter (TX) current is chosen as the self-oscillating feedback variable. The automatic delay compensation is put forward to eliminate the influence of the intrinsic delay on frequency tuning for changeable parameters. In addition, the automatic circuit parameter tuning based on the phase difference is proposed to realize the synchronous tuning of frequency and circuit parameters. The experiments verified that the synchronous tuning proposed in this paper is effective, fully automatic, and more robust than the previous self-oscillating WPT sy... [more]
Working Fluid Stability in Large-Scale Organic Rankine Cycle-Units Using Siloxanes—Long-Term Experiences and Fluid Recycling
Tobias G. Erhart, Jürgen Gölz, Ursula Eicker, Martijn van den Broek
November 28, 2018 (v1)
Keywords: fluid recycling, fluid stability, operational experience, organic rankine cycle (ORC), siloxane, working fluid
The results in this work show the influence of long-term operation on the decomposition of working fluids in eight different organic rankine cycle (ORC) power plants (both heat-led and electricity-led) in a range of 900 kW el to 2 MW el . All case study plants are using octamethyltrisiloxane (MDM) as a working fluid; the facilities are between six to 12 years old. Detailed analyses, including the fluid distribution throughout the cycle, are conducted on one system. All presented fluid samples are analyzed via head space gas chromatography mass spectrometry (HS-GC-MS). Besides the siloxane composition, the influence of contaminants, such as mineral oil-based lubricants (and their components), is examined. In most cases, the original working fluid degrades to fractions of siloxanes with a lower boiling point (low boilers) and fractions with a higher boiling point (high boilers). As a consequence of the analyses, a new fluid recycling and management system was designed and... [more]
The Influence of Slight Protuberances in a Micro-Tube Reactor on Methane/Moist Air Catalytic Combustion
Ruirui Wang, Jingyu Ran, Xuesen Du, Juntian Niu, Wenjie Qi
November 28, 2018 (v1)
Keywords: catalytic combustion, methane/moist air, micro-tube reactor, slight protuberances
The combustion characteristics of methane/moist air in micro-tube reactors with different numbers and shapes of inner wall protuberances are investigated in this paper. The micro-reactor with one rectangular protuberance (six different sizes) was studied firstly, and it is shown that reactions near the protuberance are mainly controlled by diffusion, which has little effect on the outlet temperature and methane conversion rate. The formation of cavities and recirculation zones in the vicinity of protuberances leads to a significant increase of the Arrhenius reaction rate of CH₄ and gas velocity. Next, among the six different simulated conditions (0⁻5 rectangular protuberances), the micro-tube reactor with five rectangular protuberances shows the highest methane conversion rate. Finally, the effect of protuberance shape on methane/moist air catalytic combustion is confirmed, and it is found that the protuberance shape has a greater influence on methane conversion rate than the number of... [more]
Fundamental Active Current Adaptive Linear Neural Networks for Photovoltaic Shunt Active Power Filters
Muhammad Ammirrul Atiqi Mohd Zainuri, Mohd Amran Mohd Radzi, Azura Che Soh, Norman Mariun, Nasrudin Abd Rahim, Shahrooz Hajighorbani
November 28, 2018 (v1)
Keywords: artificial neural network (ANN), current harmonic, digital signal processor (DSP), photovoltaic (PV), shunt active power filter (SAPF), Simulink/MATLAB, total harmonic distortion (THD)
This paper presents improvement of a harmonics extraction algorithm, known as the fundamental active current (FAC) adaptive linear element (ADALINE) neural network with the integration of photovoltaic (PV) to shunt active power filters (SAPFs) as active current source. Active PV injection in SAPFs should reduce dependency on grid supply current to supply the system. In addition, with a better and faster harmonics extraction algorithm, the SAPF should perform well, especially under dynamic PV and load conditions. The role of the actual injection current from SAPF after connecting PVs will be evaluated, and the better effect of using FAC ADALINE will be confirmed. The proposed SAPF was simulated and evaluated in MATLAB/Simulink first. Then, an experimental laboratory prototype was also developed to be tested with a PV simulator (CHROMA 62100H-600S), and the algorithm was implemented using a TMS320F28335 Digital Signal Processor (DSP). From simulation and experimental results, significant... [more]
Analysis and Minimization of Output Current Ripple for Discontinuous Pulse-Width Modulation Techniques in Three-Phase Inverters
Gabriele Grandi, Jelena Loncarski, Milan Srndovic
November 27, 2018 (v1)
Keywords: harmonic distortion, inverters, pulse-width modulation (PWM), ripple minimization
This paper gives the complete analysis of the output current ripple in three-phase voltage source inverters considering the different discontinuous pulse-width modulation (DPWM) strategies. In particular, peak-to-peak current ripple amplitude is analytically evaluated over the fundamental period and compared among the most used DPWMs, including positive and negative clamped (DPWM+ and DPWM−), and the four possible combinations between them, usually named as DPWM0, DPWM1, DPWM2, and DPWM3. The maximum and the average values of peak-to-peak current ripple are estimated, and a simple method to correlate the ripple envelope with the ripple rms is proposed and verified. Furthermore, all the results obtained by DPWMs are compared to the centered pulse-width modulation (CPWM, equivalent to the space vector modulation) to identify the optimal pulse-width modulation (PWM) strategy as a function of the modulation index, taking into account the different average switching frequency. In this way,... [more]
Real-Time Optimization of Organic Rankine Cycle Systems by Extremum-Seeking Control
Andres Hernandez, Adriano Desideri, Clara Ionescu, Robin De Keyser, Vincent Lemort, Sylvain Quoilin
November 27, 2018 (v1)
Keywords: extremum-seeking (ES) control, Model Predictive Control, organic Rankine cycle
In this paper, the optimal operation of a stationary sub-critical 11 kW el organic Rankine cycle (ORC) unit for waste heat recovery (WHR) applications is investigated, both in terms of energy production and safety conditions. Simulation results of a validated dynamic model of the ORC power unit are used to derive a correlation for the evaporating temperature, which maximizes the power generation for a range of operating conditions. This idea is further extended using a perturbation-based extremum seeking (ES) algorithm to identify online the optimal evaporating temperature. Regarding safety conditions, we propose the use of the extended prediction self-adaptive control (EPSAC) approach to constrained model predictive control (MPC). Since it uses input/output models for prediction, it avoids the need for state estimators, making it a suitable tool for industrial applications. The performance of the proposed control strategy is compared to PID-like schemes. Results show that E... [more]
Optimal Operation of Combined Photovoltaic Electrolyzer Systems
Arash Khalilnejad, Aditya Sundararajan, Alireza Abbaspour, Arif Sarwat
November 27, 2018 (v1)
Keywords: advanced alkaline electrolyzer, hydrogen storage, imperialistic competitive algorithm (ICA), photovoltaic (PV)
In this study, the design and simulation of a combination of a photovoltaic (PV) array with an alkaline electrolyzer is performed to maximize the production of hydrogen as a reliable power resource. Detailed electrical model of PV system, as long as thermal and electrochemical model of electrolyzer is used. Since an electrolyzer is a non-linear load, its coupling with PV systems to get the best power transfer is very important. Solar irradiation calculations were done for the region of Miami (FL, USA), giving an optimal surface slope of 25.7° for the PV array. The size of the PV array is optimized, considering maximum hydrogen production and minimum excess power production in a diurnal operation of a system using the imperialistic competitive algorithm (ICA). The results show that for a 10 kW alkaline electrolyzer, a PV array with a nominal power of 12.3 kW The results show that 12.3 kW photvoltaic system can be utilized for supplying a 10 kW electrolyzer. Hydrogen production and Farad... [more]
A Novel DC-Bus Sensor-less MPPT Technique for Single-Stage PV Grid-Connected Inverters
Mohamed A. Elsaharty, Hamdy A. Ashour, Elyas Rakhshani, Edris Pouresmaeil, João P. S. Catalão
November 27, 2018 (v1)
Keywords: grid connected, MPPT technique, photovoltaic, sensor-less, single-stage converter
Single-stage grid connected inverters are considered as an economic, compact and simple topology compared with multi-stage inverters. In photovoltaic (PV) grid connected systems, the major requirement is to achieve maximum output power from the source. Maximum Power Point Tracking (MPPT) techniques require measurements on the DC side of the inverter connected to the PV in order to determine the current operating point on the power characteristics. Typically this is achieved by perturbing the reference output power and observe the change in the PV voltage, current or both. Based on the observation, it could be determined whether the current operating point is beyond or below maximum power. This paper presents an MPPT technique for a single-stage PV grid connected inverter where the MPPT algorithm determines the current operating point at different operating conditions based upon observing the inverter controller action. Such approach eliminates the requirement of sensing elements to be... [more]
Optimization of Shift Schedule for Hybrid Electric Vehicle with Automated Manual Transmission
Wenchen Shen, Huilong Yu, Yuhui Hu, Junqiang Xi
November 27, 2018 (v1)
Keywords: automated mechanical transmission (AMT), dynamic programming (DP), gear shift schedule, hybrid electric vehicle (HEV)
Currently, most hybrid electric vehicles (HEVs) equipped with automated mechanical transmission (AMT) are implemented with the conventional two-parameter gear shift schedule based on engineering experience. However, this approach cannot take full advantage of hybrid drives. In other words, the powertrain of an HEV is not able to work at the best fuel-economy points during the whole driving profile. To solve this problem, an optimization method of gear shift schedule for HEVs is proposed based on Dynamic Programming (DP) and a corresponding solving algorithm is also put forward. A gear shift schedule that can be employed in real-vehicle is extracted from the obtained optimal gear shift points by DP approach and is optimized based on analysis of the engineering experience in a typical Chinese urban driving cycle. Compared with the conventional two-parameter gear shift schedule in both simulation and real vehicle experiments, the extracted gear shift schedule is proved to clearly improve... [more]
Tunneling Horizontal IEC 61850 Traffic through Audio Video Bridging Streams for Flexible Microgrid Control and Protection
Michael Short, Fathi Abugchem, Muneeb Dawood
November 27, 2018 (v1)
Keywords: audio video bridging (AVB), IEC 61850, micro grid, smart grid, telecontrol and teleprotection
In this paper, it is argued that some low-level aspects of the usual IEC 61850 mapping to Ethernet are not well suited to microgrids due to their dynamic nature and geographical distribution as compared to substations. It is proposed that the integration of IEEE time-sensitive networking (TSN) concepts (which are currently implemented as audio video bridging (AVB) technologies) within an IEC 61850 / Manufacturing Message Specification framework provides a flexible and reconfigurable platform capable of overcoming such issues. A prototype test platform and bump-in-the-wire device for tunneling horizontal traffic through AVB are described. Experimental results are presented for sending IEC 61850 GOOSE (generic object oriented substation events) and SV (sampled values) messages through AVB tunnels. The obtained results verify that IEC 61850 event and sampled data may be reliably transported within the proposed framework with very low latency, even over a congested network. It is argued th... [more]
An Automatic Switched-Capacitor Cell Balancing Circuit for Series-Connected Battery Strings
Yuanmao Ye, Ka Wai Eric Cheng
November 27, 2018 (v1)
Keywords: battery, battery management system (BMS), energy storage system, switched-capacitor (SC), voltage balancing
In this paper, a novel voltage equalizer is developed for series battery strings based on the two-phase switched capacitor technique. Different from the conventional voltage equalizers which are developed by switched-mode power converters, bulky magnetic components and complex monitoring and control system are avoided in the proposed system. Just a pair of complementary pulse signals with constant switching frequency and fixed duty ratio are required to control all of switches employed in the proposed voltage equalizer, and charge transfers from the higher voltage battery cells to lower voltage ones automatically. The circuit configuration and operation principle are provided in this paper. The model of the proposed voltage equalizer is also derived. Comparison with other works indicates that the proposed method is superior to the conventional switched-capacitor (SC) voltage equalizer for the high stack of series battery strings. Experimental results demonstrate that the proposed volta... [more]
Device Performance Improvement of Double-Pass Wire Mesh Packed Solar Air Heaters under Recycling Operation Conditions
Chii-Dong Ho, Hsuan Chang, Chun-Sheng Lin, Chun-Chieh Chao, Yi-En Tien
November 16, 2018 (v1)
Keywords: double-pass, heat-transfer efficiency, recycling, solar air heater, wire mesh packing
The improvement of device performance of a recycling solar air heater featuring a wire mesh packing was investigated experimentally and theoretically. The application of the wire mesh packing and recycle-effect concept to the present study were proposed aiming to strengthen the convective heat-transfer coefficient due to increased turbulence. Comparisons were made among different designs, including the single-pass, flat-plate double-pass and recycling double-pass wire mesh packed operations. The collector efficiency of the recycling double-pass wire mesh packed solar air heater was much higher than that of the other configurations for various recycle ratios and mass flow rates scenarios. The power consumption increment due to implementing wire mesh in solar air heaters was also discussed considering the economic feasibility. A fairly good agreement between theoretical predictions and experimental measurements was achieved with an analyzed error of 1.07%⁻9.32%.
Capacitor Voltage Ripple Suppression for Z-Source Wind Energy Conversion System
Shoudao Huang, Yang Zhang, Zhikang Shuai
October 23, 2018 (v1)
Keywords: capacitor voltage ripple, pulse width modulation, wind generation system, Z-source inverter
This paper proposes an improved pulse-width modulation (PWM) strategy to reduce the capacitor voltage ripple in Z-source wind energy conversion system. In order to make sure that Z-source capacitor voltage has symmetrical maximum and minimum amplitudes in each active state, the shoot-through time is divided into six unequal parts. According to the active state and zero state, the shoot-through time is rearranged to match the charging time and discharging time of the Z-source capacitors. Theoretically, it is indicated that the voltage ripple of the Z-source capacitors can be reduced effectively by means of the proposed PWM scheme. Finally, simulation and experimental results are given to verify the performance of the presented method.
Optimal Maintenance Management of Offshore Wind Farms
Alberto Pliego Marugán, Fausto Pedro García Márquez, Jesús María Pinar Pérez
October 23, 2018 (v1)
Keywords: binary decision diagrams, fault tree analysis, maintenance management, offshore, wind turbines
Nowadays offshore wind energy is the renewable energy source with the highest growth. Offshore wind farms are composed of large and complex wind turbines, requiring a high level of reliability, availability, maintainability and safety (RAMS). Firms are employing robust remote condition monitoring systems in order to improve RAMS, considering the difficulty to access the wind farm. The main objective of this research work is to optimise the maintenance management of wind farms through the fault probability of each wind turbine. The probability has been calculated by Fault Tree Analysis (FTA) employing the Binary Decision Diagram (BDD) in order to reduce the computational cost. The fault tree presented in this paper has been designed and validated based on qualitative data from the literature and expert from important European collaborative research projects. The basic events of the fault tree have been prioritized employing the criticality method in order to use resources efficiently. E... [more]
Reliability Analysis and Overload Capability Assessment of Oil-Immersed Power Transformers
Chen Wang, Jie Wu, Jianzhou Wang, Weigang Zhao
October 23, 2018 (v1)
Keywords: current measurement, losses, power transformers, reliability estimation, transformer windings
Smart grids have been constructed so as to guarantee the security and stability of the power grid in recent years. Power transformers are a most vital component in the complicated smart grid network. Any transformer failure can cause damage of the whole power system, within which the failures caused by overloading cannot be ignored. This research gives a new insight into overload capability assessment of transformers. The hot-spot temperature of the winding is the most critical factor in measuring the overload capacity of power transformers. Thus, the hot-spot temperature is calculated to obtain the duration running time of the power transformers under overloading conditions. Then the overloading probability is fitted with the mature and widely accepted Weibull probability density function. To guarantee the accuracy of this fitting, a new objective function is proposed to obtain the desired parameters in the Weibull distributions. In addition, ten different mutation scenarios are adopt... [more]
Comparison of the Stator Step Skewed Structures for Cogging Force Reduction of Linear Flux Switching Permanent Magnet Machines
Wenjuan Hao, Yu Wang
September 21, 2018 (v1)
Keywords: cogging force, flux-switching permanent magnet machine, linear machine, step skewed stator
Linear flux switching permanent magnetic (LFSPM) machines, with the armature windings and magnets both on the mover in addition to a robust stator, are a good choice for long stoke applications, however, a large cogging force is also inevitable due to the double salient structure, and will worsen the system performance. Skewing methods are always employed for the rotary machines to reduce the cogging torque, and the rotor step-skewed method is a low-cost approximation of regular skewing. The step skewed method can also be applied to the linear machines, namely, the stator step skewed. In this paper, three stator step skewed structures, which are a three-step skewed stator, a two-step skewed stator and an improved two-step skewed stator, are employed for the cogging force reduction of two types of LFSPM machines. The three structures are analyzed and compared with emphasize on the influence of the skewed displacement on the cogging force and the average thrust force. Based on finite ele... [more]
The Impact of Pulse Charging Parameters on the Life Cycle of Lithium-Ion Polymer Batteries
J. M. Amanor-Boadu, A. Guiseppi-Elie, E. Sánchez-Sinencio
September 21, 2018 (v1)
Keywords: battery impedance, constant current constant voltage, design of experiments, electrochemical impedance spectroscopy, Li-ion polymer battery, life cycle, pulse charging, Taguchi orthogonal arrays
The pulse charging algorithm is seen as a promising battery charging technique to satisfy the needs of electronic device consumers to have fast charging and increased battery charge and energy efficiencies. However, to get the benefits of pulse charging, the pulse charge current parameters have to be chosen carefully to ensure optimal battery performance and also extend the life cycle of the battery. The impact of pulse charge current factors on the life cycle and battery characteristics are seldom investigated. This paper seeks to evaluate the impact of pulse charge current factors, such as frequency and duty cycle, on the life cycle and impedance parameters of lithium-ion polymer batteries (LiPo) while using a design of experiments approach, Taguchi orthogonal arrays. The results are compared with the benchmark constant current-constant voltage (CC-CV) charging algorithm and it is observed that by using a pulse charger at optimal parameters, the cycle life of a LiPo battery can be in... [more]
Power Transfer Efficiency Analysis for Omnidirectional Wireless Power Transfer System Using Three-Phase-Shifted Drive
Zhaohong Ye, Yue Sun, Xiufang Liu, Peiyue Wang, Chunsen Tang, Hailin Tian
September 21, 2018 (v1)
Keywords: mutual inductance coupling, omnidirectional wireless power, power transfer efficiency, three-phase-shifted drive, wireless power transfer (WPT)
In order to implement the omnidirectional wireless power transfer (WPT), a novel three-phase-shifted drive omnidirectional WPT system is proposed. This system is comprised of three independent phase-adjusted excitation sources, three orthogonal transmitting coils, and one planar receiving coil. Based on the mutual coupling theory, the power transfer efficiency is derived and the corresponding control mechanism for maximizing this efficiency is presented. This control mechanism only depends on the currents’ root-mean-square (RMS) values of the three transmitting coils and simple calculations after each location and/or posture change of the receiving coil, which provides the real-time possibility to design an omnidirectional WPT system comparing with the other omnidirectional systems. In aid of computer emulation technique, the efficiency characteristic versus the omnidirectional location and posture of the receiving coil is analyzed, and the analytical results verify the validity of the... [more]
Reconfiguration of a Multilevel Inverter with Trapezoidal Pulse Width Modulation
Nataraj Prabaharan, V. Arun, Padmanaban Sanjeevikumar, Lucian Mihet-Popa, Frede Blaabjerg
September 21, 2018 (v1)
Keywords: FPGA, inverter, multi-carrier pulse width modulation, multilevel inverter, trapezoidal pulse width modulation
This paper presents different multi-carrier unipolar trapezoidal pulse width modulation strategies for a reduced switch asymmetrical multilevel inverter. The different strategies are phase disposition, alternative phase opposition and disposition, and carrier overlapping and variable frequency that involve triangular waves as carriers with a unipolar trapezoidal wave as a reference. The reduced switch, asymmetrical multilevel inverter operation was examined for generating the seven-level output voltage using Matlab/Simulink 2009b and the results were verified with a real-time laboratory-based experimental setup using a field-programmable gate array. Different parameter analyses, such as total harmonic distortion, fundamental root mean square voltage, and distortion factor, were analyzed with different modulation indices to investigate the performance of the selected topology. Unipolar trapezoidal pulse width modulation provides a higher root mean square voltage value.
PLL-Less Three-Phase Four-Wire SAPF with STF-dq0 Technique for Harmonics Mitigation under Distorted Supply Voltage and Unbalanced Load Conditions
Yap Hoon, Mohd Amran Mohd Radzi
September 21, 2018 (v1)
Keywords: dq0 principle, harmonics filtering, neutral current, reference current generation, synchronization phase, unbalanced load, voltage source inverter
This paper presents a non-iterative technique that generates reference current to manage operation of a three-phase four-wire shunt active power filter which employs a three-leg split capacitor voltage source inverter (VSI) topology. The proposed technique integrates together a self-tuning-filter (STF) and direct-quadrature-zero (dq0) principle (referred here as STF-dq0), allowing the controlled shunt active power filter (SAPF) to perform effectively under distorted source voltages and unbalanced load conditions. Unlike the previous technique developed based on the standard dq0 principle, the proposed technique does not require any service from a phase-locked loop (PLL) where two STFs are applied to separate harmonic and fundamental elements for the purpose of generating synchronization phases and reference current, respectively. Simulation work which includes connection of the SAPF circuits, design of control techniques and all the necessary assessments are conducted in MATLAB-Simulin... [more]
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