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University of Nebraska - Lincoln
Department of Electrical and Computer Engineering: Faculty Publications
- Discipline
- Keyword
-
- static synchronous compensator (STATCOM) (2)
- Effective capacity (2)
- Energy efficiency (2)
- Fading channels (2)
- Minimum bit energy (2)
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- Real-time implementation (2)
- Spectral efficiency (2)
- energy-bandwidthdelay tradeoff. (1)
- interface neurocontroller (INC) (1)
- particle swarm optimization (PSO) (1)
- permanent-magnet synchronous generator (PMSG). (1)
- static synchronous series compensator (SSSC). (1)
- wideband slope. (1)
- wind farm. (1)
- wind turbine. (1)
- Auto-associative neural network (1)
- Bit energy (1)
- Distribution systems (1)
- Doubly fed induction generator (1)
- Doubly fed induction generators (DFIGs) (1)
- Doubly-fed induction generator (DFIG) (1)
- Doubly-fed induction generator; maximum power generation; real-time speed estimation; sensorless control; wind turbine. (1)
- Dynamic model (1)
- Fault-tolerant control (1)
- Fixed-rate transmission (1)
- Flexible ac transmission system (FACTS) device (1)
- Fundamental-frequency model (1)
- Grid loss (1)
- Heuristic dynamic programming (HDP) (1)
- Input–ouput feedback linearization (IOL) (1)
Articles 1 - 30 of 32
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Spectroscopicellipsometer And Polarmeter Systemis, John A. Woollam, Blaine D. Johs, Craig M. Herzinger, Ping He, Martin M. Liphardt, Galen L. Pfeiffer
Spectroscopicellipsometer And Polarmeter Systemis, John A. Woollam, Blaine D. Johs, Craig M. Herzinger, Ping He, Martin M. Liphardt, Galen L. Pfeiffer
Department of Electrical and Computer Engineering: Faculty Publications
A rotating compensator spectroscopic ellipsometer or polarimeter system having a source of a polychromatic beam of electromagnetic radiation, a polarizer, a stage for Supporting a material system, an analyzer, a dispersive optics and a detector system which comprises a multiplicity of detector elements, the system being functionally present in an environmental control chamber and therefore suitable for application in wide spectral range, (for example, 130-1700 nm). Preferred compensator design involves a Substantially achromatic multiple element compensator systems wherein multiple total internal reflections enter retardance into an entered beam of electromagnetic radiation, and the elements thereof are oriented to minimize changes …
Graphene On Pt(111): Growth And Substrate Interaction, Peter Sutter, Jerzy T. Sadowski, Eli Sutter
Graphene On Pt(111): Growth And Substrate Interaction, Peter Sutter, Jerzy T. Sadowski, Eli Sutter
Department of Electrical and Computer Engineering: Faculty Publications
In situ low-energy electron microscopy (LEEM) of graphene growth combined with measurements of the graphene structure and electronic band structure has been used to study graphene on Pt (111). Growth by carbon segregation produces macroscopic monolayer graphene domains extending continuously across Pt (111) substrate steps and bounded by strongly faceted edges. LEEM during cooling from the growth temperature shows the propagation of wrinkles in the graphene sheet, driven by thermal stress. The lattice mismatch between graphene and Pt (111) is accommodated by moiré structures with a large number of different rotational variants, without a clear preference for a particular interface …
Power Efficiency Of Cooperative Communication In Wireless Sensor Networks, Sunita Gupta, Mehmet C. Vuran, M. Cenk Gursoy
Power Efficiency Of Cooperative Communication In Wireless Sensor Networks, Sunita Gupta, Mehmet C. Vuran, M. Cenk Gursoy
Department of Electrical and Computer Engineering: Faculty Publications
In this paper, a new protocol termed CoopXLM that integrates cooperative communication and Cross-Layer Module (XLM) is created and examined via simulation. CoopXLM modifies XLM by allowing multiple cooperative nodes to participate in receiver-based contention. Although there is increased energy consumption for processing, simulation results indicate that across all duty cycles there is an average energy savings of 38% with CoopXLM in comparison to XLM. It was also found that CoopXLM yields higher goodput than XLM at lower duty cycles but yields lower goodput at higher duty cycles.
Power Consumption And Performance Analysis Of Object Tracking And Event Detection With Wireless Embedded Smart Cameras, Mauricio Casares, Alvaro Pinto, Youlu Wang, Senem Velipasalar
Power Consumption And Performance Analysis Of Object Tracking And Event Detection With Wireless Embedded Smart Cameras, Mauricio Casares, Alvaro Pinto, Youlu Wang, Senem Velipasalar
Department of Electrical and Computer Engineering: Faculty Publications
An embedded smart camera is a stand-alone unit that not only captures images, but also includes a processor, memory and communication interface. With battery-powered and embedded smart cameras, it has become viable to install many spatially-distributed cameras interconnected by wireless links. Not requiring to have access to electrical outlets and have wired links increase system flexibility. However, wireless and battery-powered smart-camera networks introduce many additional challenges since they have very limited resources, such as power, memory and bandwidth. The algorithms running on the camera boards should be lightweight and efficient. In addition, the frequency of communication between camera nodes, and …
Scanning Tunneling Microscopy On Epitaxial Bilayer Graphene On Ruthenium (0001), Eli A. Sutter, D.P. Acharya, J.T. Sadowski, P. Sutter
Scanning Tunneling Microscopy On Epitaxial Bilayer Graphene On Ruthenium (0001), Eli A. Sutter, D.P. Acharya, J.T. Sadowski, P. Sutter
Department of Electrical and Computer Engineering: Faculty Publications
The atomic structure of epitaxial single and bilayer graphene on Ru(0001) was studied by scanning tunneling microscopy (STM). High-resolution imaging of the surface of single layer graphene shows a moiré with pronounced buckling and broken A/B carbon sublayer symmetry due to a strong interaction with the metal substrate. The top sheet of bilayer graphene is largely unperturbed by residual interactions with the substrate. Screened from the metal substrate, it shows the hallmarks of freestanding monolayer graphene: a honeycomb structure with equivalent carbon sublattices imaged in STM and a linear dispersion of bands near the Dirac point.
Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, Johns A. Woollam, James D. Welch
Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, Johns A. Woollam, James D. Welch
Department of Electrical and Computer Engineering: Faculty Publications
Systems and methodology for orienting the tip/tilt ad vertical height of samples, preferably automated, as applied in ellipsometer and the like systems
Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, John A. Woollam, James D. Welch
Automated Ellipsometer And The Like Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, John A. Woollam, James D. Welch
Department of Electrical and Computer Engineering: Faculty Publications
Systems and methodology for orienting the tip/tilt and vertical height of samples, preferably automated, as applied in ellipsometer and the like systems.
Achievable Rates And Resource Allocation Strategies For Imperfectly Known Fading Relay Channels, Junwei Zhang, M. Cenk Gursoy
Achievable Rates And Resource Allocation Strategies For Imperfectly Known Fading Relay Channels, Junwei Zhang, M. Cenk Gursoy
Department of Electrical and Computer Engineering: Faculty Publications
Achievable rates and resource allocation strategies for imperfectly known fading relay channels are studied. It is assumed that communication starts with the network training phase in which the receivers estimate the fading coefficients. Achievable rate expressions for amplify-and-forward and decode-and-forward relaying schemes with different degrees of cooperation are obtained. We identify efficient strategies in three resource allocation problems: (1) power allocation between data and training symbols, (2) time/bandwidth allocation to the relay, and (3) power allocation between the source and relay in the presence of total power constraints. It is noted that unless the source-relay channel quality is high, cooperation …
Ground-Plane Quasicloaking For Free Space, Efthymios Kallos, Christos Argyropoulos, Yang Hao
Ground-Plane Quasicloaking For Free Space, Efthymios Kallos, Christos Argyropoulos, Yang Hao
Department of Electrical and Computer Engineering: Faculty Publications
Ground-plane cloak designs are presented, which minimize scattering of electromagnetic radiation from metallic objects in the visible spectrum. It is showed that simplified ground-plane cloaks made from only a few blocks of all-dielectric isotropic materials, either embedded in a background medium or in free space, can provide considerable cloaking performance while maintaining their broadband nature. A design which operates isolated in free space that cloaks radiation originating from a specified direction is also analyzed. These schemes should be much easier to be demonstrated experimentally compared to full designs.
Sequencing, Analysis, And Annotation Of Expressed Sequence Tags For Camelus Dromedarius, Abdulaziz M. Al-Swailem, Maher M. Shehata, Faisel M. Abu-Duhier, Essam J. Al-Yamani, Khalid A. Al-Busadah, Mohammed S. Al-Arawi, Ali Y. Al-Khider, Abdullah N. Al-Muhaimeed, Fahad H. Al-Qahtani, Manee M. Manee, Badr M. Al-Shomrani, Saad M. Al-Qhtani, Amer S. Al-Harthi, Kadir C. Akdemir, Mehmet S. Inan, Hasan H. Otu
Sequencing, Analysis, And Annotation Of Expressed Sequence Tags For Camelus Dromedarius, Abdulaziz M. Al-Swailem, Maher M. Shehata, Faisel M. Abu-Duhier, Essam J. Al-Yamani, Khalid A. Al-Busadah, Mohammed S. Al-Arawi, Ali Y. Al-Khider, Abdullah N. Al-Muhaimeed, Fahad H. Al-Qahtani, Manee M. Manee, Badr M. Al-Shomrani, Saad M. Al-Qhtani, Amer S. Al-Harthi, Kadir C. Akdemir, Mehmet S. Inan, Hasan H. Otu
Department of Electrical and Computer Engineering: Faculty Publications
Despite its economical, cultural, and biological importance, there has not been a large scale sequencing project to date for Camelus dromedarius. With the goal of sequencing complete DNA of the organism, we first established and sequenced camel EST libraries, generating 70,272 reads. Following trimming, chimera check, repeat masking, cluster and assembly, we obtained 23,602 putative gene sequences, out of which over 4,500 potentially novel or fast evolving gene sequences do not carry any homology to other available genomes. Functional annotation of sequences with similarities in nucleotide and protein databases has been obtained using Gene Ontology classification. Comparison to available …
Genes Differentially Expressed By Cumulus Cells And Assays Using Same To Identify Pregnancy Competent Oocytes, Jose B. Cibelli, Amy E. Iager, Hasan H. Otu
Genes Differentially Expressed By Cumulus Cells And Assays Using Same To Identify Pregnancy Competent Oocytes, Jose B. Cibelli, Amy E. Iager, Hasan H. Otu
Department of Electrical and Computer Engineering: Faculty Publications
A genetic means of identifying "pregnancy competent" oocytes is provided. The means comprises detecting the level of expression of one or more genes that are expressed at characteristic levels (upregulated or downregulated) in cumulus cells derived from pregnancy competent oocytes. This characteristic gene expression level, or pattern referred to herein as the "pregnancy signature", also can be used to identify subjects with underlying conditions that impair or prevent the development of a viable pregnancy, e.g., pre-menopausal condition, other hormonal dysfunction, ovarian dysfunction, ovarian cyst, cancer or other cell proliferation disorder, autoimmune disease and the like. In preferred embodiments the …
Samplemaskinginellipsometerand The Like Systems Including Detection Of Substrate Backside Reflections, Martin M. Liphardt, James D. Welch, Corey L. Bungay, John A. Woollam
Samplemaskinginellipsometerand The Like Systems Including Detection Of Substrate Backside Reflections, Martin M. Liphardt, James D. Welch, Corey L. Bungay, John A. Woollam
Department of Electrical and Computer Engineering: Faculty Publications
A system and method of preventing substrate backside reflected components in a beam of electromagnetic radiation caused to reflect from the surface of a sample in an ellipsometer or polarimeter system, involving placing a mask adjacent to the surface of the sample which allows electromagnetic radiation to access the sample over only a limited area, wherein to access the sample over only a limited area, wherein the mask can include detector elements for collecting electromagnetic radiation reflected from the sample backside.
Sample Investigating System, Martin M. Liphardt, Thomas E. Tiwald, Blaine D. Johs, Jeffery S. Hale, Craig M. Herzinger, Steven E. Green, Ping He, Ronald A. Synowicki, John A. Woollam
Sample Investigating System, Martin M. Liphardt, Thomas E. Tiwald, Blaine D. Johs, Jeffery S. Hale, Craig M. Herzinger, Steven E. Green, Ping He, Ronald A. Synowicki, John A. Woollam
Department of Electrical and Computer Engineering: Faculty Publications
A spectroscopic system for adjusting spacing between an adjacent source/detector as a unit, and a sample, and a reflecting means for directing an incident beam which refelcts from said sample back onto said sample and then into the detector along a locus which is in a plance of incidence that is offset from that of the incident beam, or directly from the reflecting means into the detecor, including means for reducing reflections of a beam fo electromagnetic from the back of a sample, including methodology of use.
Simulation Of Coherent Radar Imaging Using Continuous Wave Noise Radar, Jing Xu, Michael Hoffman, B.L. Cheong, R.D. Palmer
Simulation Of Coherent Radar Imaging Using Continuous Wave Noise Radar, Jing Xu, Michael Hoffman, B.L. Cheong, R.D. Palmer
Department of Electrical and Computer Engineering: Faculty Publications
A computationally simple cross-correlation model for multiple backscattering from a continuous wave (CW) noise radar is developed and verified with theoretical analysis and brute-force time-domain simulations. Based on this cross-correlation model, a modification of an existing numerical method originally developed by Holdsworth and Reid for spaced antenna (SA) pulsed radar is used to simulate the estimated cross correlation corresponding to atmospheric backscattering using a coherent CW noise radar. Subse- quently, coherent radar imaging (CRI) processing comparisons between the CW noise radar and a con- ventional pulsed radar are presented that verify the potential of CW noise radar for atmospheric imaging.
Thin Films Formed By Selenization Of CuinXB1−X Precursors In Se Vapor, C. A. Kamler, Rodney J. Soukup, Natale J. Ianno, J. L. Huguenin-Love, J. Olejníček, S. A. Darveau, C. L. Exstrom
Thin Films Formed By Selenization Of CuinXB1−X Precursors In Se Vapor, C. A. Kamler, Rodney J. Soukup, Natale J. Ianno, J. L. Huguenin-Love, J. Olejníček, S. A. Darveau, C. L. Exstrom
Department of Electrical and Computer Engineering: Faculty Publications
Previous attempts in producing light absorbing materials with bandgaps near the 1.37 eV efficiency optimum have included the partial substitution of gallium or aluminum for indium in the CIS system. The most efficient of these solar cells to date have had absorber layers with bandgaps < 1.2 eV. It is logical that an even smaller substitutional atom, boron, should lead to a wider bandgap with a smaller degree of atomic substitution. In this study, copper–indium–boron precursor films are sputtered onto molybdenum coated glass substrates and post-selenized. In the selenized films, although X-ray diffraction (XRD) measurements confirm that a CIS phase is present, Auger electron spectroscopy (AES) results indicate that boron is no longer homogeneously dispersed throughout the film as it was in the case of the unselenized precursor.
Controlled Growth Of Carbon Nanotubes On Electrodes Under Different Bias Polarity, Yi Gao, Yunshen Zhou, W. Xiong, M. Mahjouri-Samani, M. Mitchell, Yongfeng Lu
Controlled Growth Of Carbon Nanotubes On Electrodes Under Different Bias Polarity, Yi Gao, Yunshen Zhou, W. Xiong, M. Mahjouri-Samani, M. Mitchell, Yongfeng Lu
Department of Electrical and Computer Engineering: Faculty Publications
Carbon nanotubes (CNTs) of different alignments, such as surface-bounded and vertically aligned arrays, enable applications in different fields. In this study, controlled growth of CNTs with different alignments was achieved by electrically biasing catalyzed electrodes with different polarities in a laser-assisted chemical vapor deposition process. CNT growth was suggested to be guided by the movement of electrically charged catalyst-nanoparticles under the influence of an external electric field. This discovery provides a convenient approach to control the alignment of CNT arrays for different applications.
Energy Efficiency Of Fixed-Rate Wireless Transmissions Under Queueing Constraints And Channel Uncertainty, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
Energy Efficiency Of Fixed-Rate Wireless Transmissions Under Queueing Constraints And Channel Uncertainty, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
Department of Electrical and Computer Engineering: Faculty Publications
Energy efficiency of fixed-rate transmissions is studied in the presence of queueing constraints and channel uncertainty. It is assumed that neither the transmitter nor the receiver has channel side information prior to transmission. The channel coefficients are estimated at the receiver via minimum mean-square-error (MMSE) estimation with the aid of training symbols. It is further assumed that the system operates under statistical queueing constraints in the form of limitations on buffer violation probabilities. The optimal fraction of power allocated to training is identified. Spectral efficiency–bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity …
Energy Efficiency Of Fixed-Rate Wireless Transmissions Under Qos Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
Energy Efficiency Of Fixed-Rate Wireless Transmissions Under Qos Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
Department of Electrical and Computer Engineering: Faculty Publications
Transmission over wireless fading channels under quality of service (QoS) constraints is studied when only the receiver has perfect channel side information. Being unaware of the channel conditions, transmitter is assumed to send the information at a fixed rate. Under these assumptions, a two-state (ON-OFF) transmission model is adopted, where information is transmitted reliably at a fixed rate in the ON state while no reliable transmission occurs in the OFF state. QoS limitations are imposed as constraints on buffer violation probabilities, and effective capacity formulation is used to identify the maximum arrival rate that a wireless channel can sustain while …
Analysis Of Energy Efficiency In Fading Channels Under Qos Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
Analysis Of Energy Efficiency In Fading Channels Under Qos Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
Department of Electrical and Computer Engineering: Faculty Publications
Energy efficiency in fading channels in the presence of Quality of Service (QoS) constraints is studied. Effective capacity, which provides the maximum arrival rate that a wireless channel can sustain while satisfying statistical QoS constraints, is considered. Spectral efficiency–bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity formulation, rather than the Shannon capacity. Through this analysis, energy requirements under QoS constraints are identified. The analysis is conducted under two assumptions: perfect channel side information (CSI) available only at the receiver and perfect CSI available at both the receiver and transmitter. In particular, it …
The Impact Of Qos Constraints On The Energy Efficiency Of Fixed-Rate Wireless Transmissions, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
The Impact Of Qos Constraints On The Energy Efficiency Of Fixed-Rate Wireless Transmissions, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar
Department of Electrical and Computer Engineering: Faculty Publications
Transmission over wireless fading channels under quality of service (QoS) constraints is studied when only the receiver has channel side information. Being unaware of the channel conditions, transmitter is assumed to send the information at a fixed rate. Under these assumptions, a two-state (ON-OFF) transmission model is adopted, where information is transmitted reliably at a fixed rate in the ON state while no reliable transmission occurs in the OFF state. QoS limitations are imposed as constraints on buffer violation probabilities, and effective capacity formulation is used to identify the maximum throughput that a wireless channel can sustain while satisfying statistical …
Output Maximization Control For Dfig Wind Turbines Without Using Wind And Shaft Speed Measurements, Wei Qiao, Xiang Gong, Liyan Qu
Output Maximization Control For Dfig Wind Turbines Without Using Wind And Shaft Speed Measurements, Wei Qiao, Xiang Gong, Liyan Qu
Department of Electrical and Computer Engineering: Faculty Publications
Wind turbine generators (WTGs) are usually equipped with mechanical sensors to measure wind speed and turbine shaft rotating speed for system monitoring, control, and protection. The use of these sensors increases the cost and hardware complexity and reduces the reliability of the WTG system. This paper proposes a novel real-time speed estimation algorithm for wind turbines equipped with doubly-fed induction generators (DFIGs). In the proposed algorithm, both the wind and turbine shaft speeds are estimated from the measured DFIG output electrical power. The estimated speeds are then used to determine the maximum power point of the DFIG wind turbine. A …
Coordinated Reactive Power Control Of A Large Wind Farm And A Statcom Using Heuristic Dynamic Programming, Wei Qiao, Ronald D. Harley, Ganesh Kumar Venayagamoorthy
Coordinated Reactive Power Control Of A Large Wind Farm And A Statcom Using Heuristic Dynamic Programming, Wei Qiao, Ronald D. Harley, Ganesh Kumar Venayagamoorthy
Department of Electrical and Computer Engineering: Faculty Publications
A novel interface neurocontroller (INC) is proposed for the coordinated reactive power control between a large wind farm equipped with doubly fed induction generators (DFIGs) and a static synchronous compensator (STATCOM). The heuristic dynamic programming (HDP) technique and radial basis function neural networks (RBFNNs) are used to design this INC. It effectively reduces the level of voltage sags as well as the over-currents in the DFIG rotor circuit during grid faults, and therefore, significantly enhances the fault ride-through capability of the wind farm. The INC also acts as a coordinated external damping controller for the wind farm and the STATCOM, …
Control Of Ipm Synchronous Generator For Maximum Wind Power Generation Considering Magnetic Saturation, Wei Qiao, Qu, Richard G. Harley
Control Of Ipm Synchronous Generator For Maximum Wind Power Generation Considering Magnetic Saturation, Wei Qiao, Qu, Richard G. Harley
Department of Electrical and Computer Engineering: Faculty Publications
Permanent-magnet synchronous generators (PMSGs) are commonly used for small variable-speed wind turbines to produce high-efficiency, high-reliability, and low-cost wind power generation. This paper proposes a novel control scheme for an interior PMSG (IPMSG) driven by a wind turbine, in which the d-axis and q-axis stator-current components are optimally controlled to achieve the maximum wind power generation and loss minimization of the IPMSG. The effect of magnetic saturation, which causes the highly nonlinear characteristics of the IPMSG, is considered in the control-scheme design. The optimal d-axis stator-current command is obtained as a function of the IPMSG rotor speed by solving a …
Real-Time Implementation Of A Statcom On A Wind Farm Equipped With Doubly Fed Induction Generators, Wei Qiao, Ganesh Kumar Venayagamoorthy, Ronald G. Harley
Real-Time Implementation Of A Statcom On A Wind Farm Equipped With Doubly Fed Induction Generators, Wei Qiao, Ganesh Kumar Venayagamoorthy, Ronald G. Harley
Department of Electrical and Computer Engineering: Faculty Publications
Voltage stability is a key issue to achieve the uninterrupted operation of wind farms equipped with doubly fed induction generators (DFIGs) during grid faults. This paper investigates the application of a static synchronous compensator (STATCOM) to assist with the uninterrupted operation of a wind turbine driving a DFIG, which is connected to a power network, during grid faults. The control schemes of the DFIG rotor- and grid-side converters and the STATCOM are suitably designed and coordinated. The system is implemented in real-time on a Real Time Digital Simulator. Results show that the STATCOM improves the transient voltage stability and therefore …
Missing-Sensor-Fault-Tolerant Control For Sssc Facts Device With Real-Time Implementation, Wei Qiao, Ganesh Kumar Venayagamoorthy, Ronald G. Harley
Missing-Sensor-Fault-Tolerant Control For Sssc Facts Device With Real-Time Implementation, Wei Qiao, Ganesh Kumar Venayagamoorthy, Ronald G. Harley
Department of Electrical and Computer Engineering: Faculty Publications
Control of power systems relies on the availability and quality of sensor measurements. However, measurements are inevitably subjected to faults caused by sensor failure, broken or bad connections, bad communication, or malfunction of some hardware or software. These faults, in turn, may cause the failure of power system controllers and consequently, severe contingencies in the power system. To avoid such contingencies, this paper presents a sensor evaluation and (missing sensor) restoration scheme (SERS) by using auto-associative neural networks (auto encoders) and particle swarm optimization. Based on the SERS, a missing-sensor-fault-tolerant control is developed for controlling a static synchronous series compensator …
Echo-State-Network-Based Real-Time Wind Speed Estimation For Wind Power Generation, Wei Qiao
Echo-State-Network-Based Real-Time Wind Speed Estimation For Wind Power Generation, Wei Qiao
Department of Electrical and Computer Engineering: Faculty Publications
Wind turbine generators (WTGs) are usually equipped with one or more well-calibrated nemometers to measure wind speed for system monitoring, control, and protection. The use of these mechanical sensors increases the cost and hardware complexity and reduces the reliability of the WTG system. This paper proposes an echo-state-network (ESN)-based real-time wind speed estimation algorithm for WTG systems. The ESN is designed to provide a nonlinear inverse model of the WTG dynamics, which is used to estimate the wind speed in real time from the measured WTG output electrical power and shaft speed at any turbine blade pitch angle. The estimated …
Voltage Analysis Of Distribution Systems With Dfig Wind Turbines, Baohua Dong, Sohrab Asgarpoor, Wei Qiao
Voltage Analysis Of Distribution Systems With Dfig Wind Turbines, Baohua Dong, Sohrab Asgarpoor, Wei Qiao
Department of Electrical and Computer Engineering: Faculty Publications
Wind energy is becoming the most viable renewable energy source mainly because of the growing concerns over carbon emissions and uncertainties in fossil fuel supplies and the government policy impetus. The increasing penetration of wind power in distribution systems may significantly affect voltage stability of the systems, particularly during wind turbine cut-in and cut-off disturbances. Currently, doubly fed induction generator wind turbine (DFIG-WT) is the most popular wind turbine. This paper investigates the issues of voltage stability improvement and grid-loss reduction of distribution systems which include DFIG-WTs under unbalanced heavy loading conditions. Simulation studies are carried out in IEEE 34-bus …
Coordinated Reactive Power Control Of A Large Wind Farm And A Statcom Using Heuristic Dynamic Programming, Wei Qiao, Ronald G. Harley, Ganesh Venayagamoorthy
Coordinated Reactive Power Control Of A Large Wind Farm And A Statcom Using Heuristic Dynamic Programming, Wei Qiao, Ronald G. Harley, Ganesh Venayagamoorthy
Department of Electrical and Computer Engineering: Faculty Publications
A novel interface neurocontroller (INC) is proposed for the coordinated reactive power control between a large wind farmequippedwith doubly fed induction generators (DFIGs) and a static synchronous compensator (STATCOM). The heuristic dynamic programming (HDP) technique and radial basis function neural networks (RBFNNs) are used to design this INC. It effectively reduces the level of voltage sags as well as the over-currents in the DFIG rotor circuit during grid faults, and therefore, significantly enhances the fault ride-through capability of thewind farm. The INCalso acts as a coordinated external damping controller for the wind farm and the STATCOM, and therefore, improves power …
Missing-Sensor-Fault-Tolerant Control For Sssc Facts Device With Real-Time Implementation, Wei Qiao, Ganesh Venayagamoorthy, Ronald G. Harley
Missing-Sensor-Fault-Tolerant Control For Sssc Facts Device With Real-Time Implementation, Wei Qiao, Ganesh Venayagamoorthy, Ronald G. Harley
Department of Electrical and Computer Engineering: Faculty Publications
Control of power systems relies on the availability and quality of sensor measurements. However, measurements are inevitably subjected to faults caused by sensor failure, broken or bad connections, bad communication, or malfunction of some hardware or software. These faults in turn may cause the failure of power system controllers and consequently severe contingencies in the power system. To avoid such contingencies, this paper resents a sensor evaluation and (missing sensor) restoration scheme (SERS) by using auto-associative neural networks (auto-encoders) and particle swarm optimization (PSO). Based on the SERS, a missing-sensor-fault-tolerant control (MSFTC) is developed for controlling a static synchronous series …
Dynamic Modeling And Control Of Doubly Fed Induction Generators Driven By Wind Turbines, Wei Qiao
Dynamic Modeling And Control Of Doubly Fed Induction Generators Driven By Wind Turbines, Wei Qiao
Department of Electrical and Computer Engineering: Faculty Publications
Two different models are presented and developed in PSCAD/EMTDC to represent a variable-speed wind turbine equipped with a doubly fed induction generator (DFIG). One is the most detailed switching-level (SL) model. The other is a simplified fundamental-frequency (FF) model. The effect of different shaft system representations on the dynamic behavior of the wind turbine generator (WTG) system and the issue of damping low-frequency torsional oscillations are investigated. Dynamic and transient simulation studies are carried out to compare two models with different shaft system representations. Results show that the FF model is sufficient while the lumpedmass shaft model is insufficient to …