28 results
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2. Grounding and Ground Fault Protection of Multiple Generator Installations on Medium-Voltage Industrial and Commercial Power Systems -- Part 1: The Problem Defined Working Group Report.
- Author
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Pillai, Prafulla, Bailey, Bruce G., Bowen, Jim, Dalke, Gerald, Douglas, Bruce G., Fischer, Jay, Jones, James R., Love, Daniel J., Mozina, Charles J., Nichols, Neil, Normand, Clifford, Padden, Lorraine, Pierce, Alan, Powell, Louie J., Shipp, David D., Stringer, Norman Terry, and Young, Ralph N.
- Subjects
ELECTRIC current grounding ,ELECTRIC generators ,ELECTRIC power ,INDUSTRIAL applications ,ELECTRIC machinery ,ENGINEERING - Abstract
This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
3. An Update on the Spreadsheet Electrical Reliability Model.
- Author
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Propst, John E., Koval, Don O., and Zhenfu Dong
- Subjects
ELECTRONIC spreadsheets ,RELIABILITY in engineering ,CHEMICAL industry ,METHODOLOGY ,ELECTRONIC data processing ,SYSTEMS engineering ,ENGINEERING - Abstract
Over the past 12 years, a number of changes and enhancements have been made to the Spreadsheet Electrical Reliability Model that was introduced at the 1994 IEEE Petroleum and Chemical Industry Committee (PCIC) Conference. Several papers have been written since then, addressing some of the changes. Papers have also been written related to the application of the spreadsheet methodology to the IEEE Gold Book standard net- work. This paper will briefly review the history of the Spreadsheet Modeling technique and review features of the latest version. This paper discusses the impact that common causes can have on industrial electrical system reliability analysis. This paper also introduces an alternate network for evaluating reliability analysis methodologies. As in the past, the latest version of the Spreadsheet Model will be made available as free shareware on the PCIC web site. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
4. Reliability Block Diagram Simulation Techniques Applied to the IEEE Std. 493 Standard Network.
- Author
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Wendai Wang, Loman, James M., Arno, Robert G., Vassiliou, Pantelis, Furlong, Edward R., and Ogden, Doug
- Subjects
TECHNOLOGY ,METHODOLOGY ,ELECTRIC power ,ELECTRONICS ,ENGINEERING ,POWER resources ,ELECTRIC utilities - Abstract
This is one of a series of papers discussing the application and accuracy of different analysis techniques supporting the determination of industrial and commercial power system reliability and availability. There is a need recognized in the power industry to identify and utilize a standard tool, or a set of tools, to analyze the reliability of power systems. historically, the results of applying different reliability methodologies and tools varied significantly, and comparisons were difficult. The Reliability Analysis Techniques Working Group of the Gold Book (WEE Std. 493-1997) developed a standard network to enable comparison of analytical techniques. This paper describes the approach of simulations via reliability block diagrams as applied to the Gold Book standard network. Reliability indexes of the load points are presented, and are compared with ones obtained from other techniques in the series to determine the accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
5. Harmonic Order Tracking Analysis: A Speed-Sensorless Method for Condition Monitoring of Wound Rotor Induction Generators.
- Author
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Sapena-Bano, Angel, Riera-Guasp, Martin, Puche-Panadero, Ruben, Martinez-Roman, Javier, Perez-Cruz, Juan, and Pineda-Sanchez, Manuel
- Subjects
INDUCTION generators ,ALTERNATING current generators ,TECHNOLOGY ,ENERGY consumption ,ENGINEERING - Abstract
This paper introduces a speed-sensorless method for detecting rotor asymmetries in wound rotor induction machines working under nonstationary conditions. The method is based on the time–frequency analysis of rotor currents and on a subsequent transformation, which leads to the following goals: unlike conventional spectrograms, it enables to show the diagnostic results as a simple graph, similar to a Fourier spectrum, but where the fault components are placed always at the same positions, regardless the working conditions of the machine; moreover, it enables to assess the machine condition through a very small set of parameters. These characteristics facilitate the understanding and processing of the diagnostic results, and thus, help to design improved monitoring and predictive maintenance systems. Also these features make the proposed method very suitable for condition monitoring of wind power generators, because it fits well with the usual nonstationary working conditions of wind turbines, and makes feasible the transmission of significant diagnostic information to the remote monitoring center using standard data transmission systems. Simulation results and experimental tests, carried out on a 5-kW laboratory rig, show the validity of the proposed method and illustrate its advantages regarding previously developed diagnostic methods under nonstationary conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
6. Inertia Design Methods for Islanded Microgrids Having Static and Rotating Energy Sources.
- Author
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Soni, Nimish, Doolla, Suryanarayana, and Chandorkar, Mukul C.
- Subjects
ELECTRIC power ,POWER resources ,TECHNOLOGY ,ENERGY consumption ,ENGINEERING - Abstract
Dynamic frequency regulation and effect of penetration of static and inertial sources on system stability are important issues for islanded microgrid power quality and reliability. This paper presents a novel strategy of utilizing an inverter-based source as a voltage source inverter or virtual synchronous generator (VSG). Electromechanical and power modes are critical for small signal stability of an isolated microgrid having static and inertial sources. Interaction of these modes is analyzed through eigenvalue analysis of microgrid model and differential equations describing respective modes. Inertia is important for providing fault current, determining steady state and transient stability, and better system frequency profile. A novel technique is proposed to include inertia virtually to the inverter-based sources by adding swing equation. Furthermore, inverter-based sources with traditional and modified droop controls and VSGs are compared with respect to inertia, energy, and stability. The proposed control and stability comparison are verified through experimental microgrid setup having three inverter-based sources, which can be alternately operated as VSGs. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
7. Dead-Time Issues in Predictive Current Control.
- Author
-
Summers, Terrence J. and Betz, Robert E.
- Subjects
ELECTRONIC systems ,ELECTRONIC equipment ,ENGINEERING ,ELECTRICITY ,ALGORITHMS ,ELECTRONICS - Abstract
Current control in inverter-driven machine systems is the inner most component of the hierarchy of control loops. If the control of current in the machine is not fast and accurate then it is difficult, if not impossible, to build a high-performance drive system. Unfortunately, the implementation of current control in power electronic systems is not ideal. Practical effects can have a significant influence on its performance. This paper examines one of these effects, dead time, and considers the influence it has on the performance of predictive current controllers (PCCs). The paper presents analysis that shows that a PCC implicitly compensates for voltage loss due to dead time. Also, a modified PCC is introduced that reduces the zero-current-clamp problem caused by dead time. Simulation and experimental results are presented to verify the analysis and confirm the performance of the new algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
8. Grounding and Ground Fault Protection of Multiple Generator Installations on Medium-Voltage Industrial and Commercial Power Systems Part 3: Protection Methods Working Group Report.
- Author
-
Pillai, Prafulla, Bailey, Bruce G., Bowen, Jim, Dalke, Gerald, Douglas, Bruce G., Fischer, Jay, Jones, James R., Love, Daniel J., Mozina, Charles J., Nichols, Neil, Normand, Clifford, Padden, Lorraine, Pierce, Alan, Powell, Louie J., Shipp, David D., Stringer, Norman Terry, and Young, Ralph N.
- Subjects
ELECTRIC current grounding ,ELECTRIC generators ,ELECTRIC power ,INDUSTRIAL applications ,ELECTRIC machinery ,ENGINEERING - Abstract
This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
9. Grounding and Ground Fault Protection of Multiple Generator Installations on Medium-Voltage Industrial and Commercial Systems Part 2: Grounding Methods Working Group Report.
- Author
-
Pillai, Prafulla, Bailey, Bruce G., Bowen, Jim, Dalke, Gerald, Douglas, Bruce G., Fischer, Jay, Jones, James R., Love, Daniel J., Mozina, Charles J., Nichols, Neil, Normand, Clifford, Padden, Lorraine, Pierce, Alan, Powell, Louie J., Shipp, David D., Stringer, Norman Terry, and Young, Ralph N.
- Subjects
ELECTRIC current grounding ,ELECTRIC generators ,ELECTRIC power ,INDUSTRIAL applications ,ELECTRIC machinery ,ENGINEERING - Abstract
This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
10. A Systematic Approach for Medium-Voltage Power Factor Correction Design.
- Author
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Cooper, Carolyn L., Pragale, Ritchie O., and Dionise, Thomas J.
- Subjects
ELECTRIC power factor ,UTILITY meters ,ENGINEERING ,NUISANCES ,CATASTROPHIC illness - Abstract
The value proposition for the installation of power factor (PF) correction (PFC) to avoid costly utility penalties is easily understood. The attractive payback of such PFC opportunities often pushes the project ahead without engineering considerations. In the case of medium-voltage PFC, lack of upfront engineering can lead to unexpected consequences in the performance of the PFC equipment ranging from nuisance trips and blown fuses to catastrophic failure in the extreme. In this paper, the authors propose a systematic approach to the design of PFC for medium-voltage systems. Three actual case studies were selected to illustrate this systematic approach and show that it can be applied regardless of the size, type, and complexity of the facility. Such a methodology is composed of load flow and harmonic measurements, harmonic analysis, utility billing demand and PF analysis, and reactive compensation specification in the form of either capacitors or harmonic filters, if needed. Diverse and competing design constraints, including daily and week load cycles, nearby utility capacitors, switched or stepped requirements, specifics of utility tariffs, loads with high harmonic content, and harmonic resonance, are identified, analyzed, and then incorporated into the solution to ensure successful performance of the PFC equipment. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
11. Tuning a PID Controller for a Digital Excitation Control System.
- Author
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Kim, Kiyong and Schaefer, Richard C.
- Subjects
DIGITAL communications ,ENGINEERING ,DATA transmission systems ,VOLTAGE regulators ,SYNCHRONOUS capacitors ,TECHNOLOGY - Abstract
Some of the modem voltage regulator systems are utilizing the proportional, integral, and derivative (PID) control for stabilization Two PID tuning approaches, pole placement and pole-zero cancellation, are commonly utilized for commissioning a digital excitation system. Each approach is discussed including its performance with three excitation parameter variations. The parameters considered include system loop gain, uncertain exciter time constants, and forcing limits. This paper is intended for various engineers and technicians to provide a better understanding of how the digital controller is tuned with pros and cons for each method. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
12. Mitigation of Voltage Dips Through Distributed Generation Systems.
- Author
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Macken, Koen J. P., Bollen, Math H. J., and Belmans, Ronnie J. M.
- Subjects
ELECTRONICS ,VOLTAGE regulators ,ELECTRIC controllers ,ENGINEERING ,PHYSICAL sciences ,COMPUTER simulation - Abstract
Voltage dips are often responsible for disrupting the operation of sensitive electronic equipment. In this paper, two solutions are presented to prevent sensitive equipment from disruptive operation. Both solutions make use of distributed generation systems to maintain the voltage across the equipment in the presence of voltage dips. The emphasis of this paper is on the transient re. spouse of both solutions to balanced as well as unbalanced voltage dips. Simulations have been carried out to provide a thorough analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
13. Application of Material Characterization Techniques to Electrical Forensic Analysis.
- Author
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David Mills, T., Hoskins, Richard S., and Nemier, Marie S.
- Subjects
INDUSTRIAL equipment ,ENGINEERING ,FAILURE analysis ,TESTING ,FORENSIC sciences ,QUALITY control - Abstract
The application of forensic science techniques to electrical equipment failure investigation has not been widely documented in the engineering world. This paper is intended to share an example of using material characterization techniques to support an initial cause determination of an electrical component "failure" event The resulting conclusion supported the initial cause determination and ruled out the possibility of design deficiencies. Thus, the qualification testing of the equipment was allowed to continue to successful completion. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
14. Four-Quadrant and Zero-Speed Sensorless Control of a Switched Reluctance Motor.
- Author
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Hossain, Syed A., Husain, Iqbal, Klode, Harald, Lequesne, Bruno, Omekanda, Avoki M., and Gopalakrishnan, Suresh
- Subjects
RELUCTANCE motors ,SYNCHRONOUS electric motors ,ALTERNATING current electric motors ,SYNCHRONOUS electric machinery ,ENGINEERING - Abstract
A four-quadrant sensorless controller for switched reluctance motor (SRM) drives is presented in this paper. The drive system with appropriate turn-on and turn-off angles for each operating quadrant delivers excellent dynamic performance over a wide speed range including zero speed. The problems associated with practical implementation especially at low and zero speeds have been addressed and overcome with engineering solutions. Experimental results for a 1-kW SRM obtained on a dSPACE-based system are presented along with useful guidelines for practical implementation. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
15. Recent Important Changes in IEEE Motor and Generator Winding Insulation Diagnostic Testing Standards.
- Author
-
Stone, Greg C.
- Subjects
MOTORS ,ENGINEERING ,TECHNICAL specifications ,DESIGN ,ELECTRIC insulators & insulation ,ROTORS - Abstract
IEEE standards and test procedures are widely used by motor and generator vendors and users to commission windings in new machines, as well as evaluate the condition of the winding insulation in operating machines. Until recent revisions, the basic procedures and standards in use were written over 25 years ago. Since the 1970s, motor windings have encountered many changes in their design and manufacture. The result was that the interpretation of results in many of the standards was no longer valid for the more modern motors. Over the past five years, the IEEE Power Engineering Society has conducted a major review and updating of most of these standards. Many important changes in test procedures and interpretation guidelines have resulted. This paper reviews the main insulation standards used for stator and rotor winding diagnostic testing, and discusses the changes that have been made. Standards discussed include: IEEE 43, 56, 95, 286,522, and 1434. For example, IEEE 43-2000 now requires a minimum insulation resistance of 100 M&Ohm; for new stator windings rated 2300 V or more, rather than the "kV + 1" that was required in the past. Furthermore, the interpretation for polarization index has changed such that a motor with a polarization index of 1 is no longer automatically classed as "bad." [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
16. Trends in Advanced Motor Protection and Monitoring.
- Author
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Robinson, Jeihri, Whelan, Charles D., and Haggerty, N. Kent
- Subjects
ENGINEERING design ,MAINTENANCE equipment ,ELECTRICAL engineering ,ENGINEERING ,ELECTRIC appliance protection ,COST effectiveness - Abstract
Industrial manufacturers strive to maximize uptime of plant operations and processes. However, downtime can be a valuable asset and present many opportunities to address those critical maintenance items that can impact reliability. Since motors and associated driven equipment comprise almost 90% of the process loads, identifying and correcting these mechanical and electrical maintenance problems will reduce unplanned production shutdowns and significantly increase business profits. This paper explores the various protection technologies available to the plant and design engineer for implementation of a cost effective and reliability centered motor management program. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
17. Power Engineering Effective Solution Triangle Customer-Consultant-Manufacturer: A Case History on Meeting Energy Let-Through Requirements for a Distribution Transformer.
- Author
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Moylan, William J., McShane, C. Patrick, Corkran, Jerry L., and Pierce, Alan
- Subjects
ENGINEERING ,ELECTRIC transformers ,ENERGY transfer ,ELECTRIC generators - Abstract
Provides information on a study concerning the application of power engineering on solution triangle customer-consultant-manufacturer connections. Requirements for distribution transformer; Assessment of the reliability of medium-voltage energy-delivery systems; Development of a standby generator project.
- Published
- 2002
- Full Text
- View/download PDF
18. Electrical Fatalities Reported by Federal OSHA for Calendar Year 2014 With Consideration of Design Interventions.
- Author
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Burdge, Gavin F. and Floyd, H. Landis
- Subjects
ELECTRIC currents ,TECHNOLOGY ,ELECTRIC machinery ,ENGINEERING - Abstract
Electrical workplace fatalities for the calendar year 2014 (January 1, 2014–December 31, 2014) were evaluated from the federal Occupational Safety and Health Administration's (OSHA) list of workplace fatalities and catastrophes. Electrocutions in U.S. workplaces continue to be a concern, especially for nonelectrical workers where electrical hazards may not be sufficiently recognized. This study includes a comparison between electrical fatalities of electrical and nonelectrical workers. The most common fatality from electrocution for nonelectrical workers was contact with power lines followed by contact with an energized machine, tool, appliance, or light fixture. The most common cause of a fatality among electrical workers was contact with wiring, a transformer, or other electrical components. Possible design interventions for the prevention of electrical fatalities are suggested. Design interventions are also needed for nonelectrical workers who may work near overhead power lines. Human costs are also considered in this study. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
19. Discussion of "Electric Arcing Burn Hazards".
- Author
-
Wellman, Craig M.
- Subjects
ELECTRIC arc ,FAULT location (Engineering) ,ELECTRIC spark ,ENGINEERING - Abstract
The article presents comments of the author on researcher A.D. Stokes and D.K. Sweeting's study "Electric Arcing Burn Hazards." The paper succeeded in relating theoretical electrical power system arcing fault energy to the possible incident energy on employees in a quantitative way. It was the origin point for all arc-flash incident energy studies and programs. It enabled the development of a model that simulates the real world case where protection may be set for a relatively long time. Various tests showed that the possible arc projection distance is much smaller for equipment with short horizontal buses.
- Published
- 2006
- Full Text
- View/download PDF
20. Development of a Stator-Magnetless Linear Synchronous Motor for Sensorless Control
- Author
-
Tsuyoshi Higuchi, Masanobu Kakihara, Motomichi Ohto, Takashi Abe, Yoshiyasu Takase, Mamoru Takaki, Toru Shikayama, and Shogo Makino
- Subjects
Engineering ,Stator ,Thrust ,02 engineering and technology ,01 natural sciences ,Industrial and Manufacturing Engineering ,law.invention ,law ,Control theory ,long stroke ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Linear scale ,Electrical and Electronic Engineering ,Armature (electrical engineering) ,conveyance ,010302 applied physics ,flux-switching ,magnet-saving ,business.industry ,saliency ,020208 electrical & electronic engineering ,Linear motor ,Magnetic hysteresis ,Inductance ,Control and Systems Engineering ,Magnet ,business - Abstract
Sensorless control techniques that do not use a linear scale are desired for applications that require a long-stroke linear synchronous motor (LSM). This paper discusses the development of a stator-magnetless LSM (i.e., no magnet is mounted on the stator of the LSM) for sensorless control that includes a high-speed position estimation algorithm based on the magnetic saturation phenomenon. This paper presents a new structure of a flux-switching LSM that achieves a high saliency ratio using a cutout that results in magnetic saturation in the armature core. The effect of the sub-tooth on reducing the cogging thrust is also discussed. Furthermore, the analytical and experimental characteristics of inductance, thrust, cogging thrust, and sensorless drive control are discussed based on a prototype., IEEE Transactions on Industry Applications, 53(5), pp.4559-4568; 2017
- Published
- 2017
21. An Approach to Eliminating DC Magnetic Flux From the Series Transformer of a Dynamic Voltage Restore
- Author
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Takushi Jimichi, Hideaki Fujita, and Hirofumi Akagi
- Subjects
Engineering ,business.industry ,Industrial and Manufacturing Engineering ,Magnetic flux ,law.invention ,Dc voltage ,Control and Systems Engineering ,Control theory ,law ,Initial phase ,Voltage sag ,Voltage regulation ,Electrical and Electronic Engineering ,Transformer ,business ,Control methods ,Voltage - Abstract
This paper proposes a control method for eliminating dc magnetic flux from the series transformer of a dynamic voltage restorer. The method is characterized by intentionally injecting no compensating voltage during a one-sixth line cycle (=3.3 ms at 50 Hz). The control method is independent of an initial phase angle of a voltage sag, thus requiring no flux detection. The period, during which no compensating voltage is injected, is one-third as short as that of an existing method. This paper confirms the effectiveness and viability of the proposed method. A 200-V 5-kW laboratory system verifies experimentally that the proposed method brings no dc magnetic flux to the series transformer. Moreover, the proposed method brings a smaller dc voltage drop to the dc load of a three-phase diode rectifier than the existing method does in the same conditions.
- Published
- 2008
22. Table of Contents.
- Subjects
ELECTRICAL engineering ,ELECTRICITY ,ENGINEERING - Abstract
Presents the table of contents for this issue of the publication. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
23. Table of Contents.
- Subjects
INDUSTRIALIZATION ,ENGINEERING - Abstract
The table of contents for the June 2013 issue of "IEEE Transactions on Industry Applications" is presented.
- Published
- 2013
- Full Text
- View/download PDF
24. Secondary Selective System Residual Bus Transfer -- A Modem Application Approach.
- Author
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Cossé Jr., Roy B., Bowen, James E., and Kerr, Stephen H.
- Subjects
PROGRAMMABLE controllers ,ENGINEERING ,PROGRAMMABLE logic devices ,LOGIC devices ,MOTION control devices ,PROCESS control systems - Abstract
A traditional secondary selective residual bus automatic transfer scheme is reviewed, and the basic logic necessary for automatic transfer operation is discussed. Although many transfer scheme documents are available, the authors believe the scheme complexity should challenge application engineers to better under- stand the "Why's" rather than the "How To's" of the application. A modern programmable logic controller approach is proposed as a contemporary solution to a complex control application. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
25. A Speed-Sensorless Start-Up Method of an Induction Motor Driven by a Modular Multilevel Cascade Inverter (MMCI-DSCC)
- Author
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Hirofumi Akagi, Yuhei Okazaki, and Makoto Hagiwara
- Subjects
Electric motor ,Engineering ,Universal motor ,Vector control ,Torque motor ,Computer science ,Stator ,business.industry ,Control engineering ,AC motor ,Industrial and Manufacturing Engineering ,Wound rotor motor ,law.invention ,Chopper ,Motor drive ,Direct torque control ,Control and Systems Engineering ,Cascade ,Control theory ,law ,Torque ,Inverter ,Electrical and Electronic Engineering ,business ,Induction motor - Abstract
This paper presents theoretical and experimental discussions on a practical speed-sensorless start-up method for an induction motor driven by a modular multilevel cascade inverter based on double-star chopper cells (MMCI-DSCC) from standstill to middle speed. This motor drive is suitable, particularly for a large-capacity fan- or blower-like load. The load torque is proportional to a square of the motor mechanical speed. The start-up method is characterized by combining capacitor-voltage control with motor-speed control. The motor-speed control with the minimal stator current plays a crucial role in eliminating a speed sensor from the drive system and in reducing an ac-voltage fluctuation occurring across each dc capacitor. Experimental results obtained from the 400-V 15-kW downscaled system with no speed sensor verify that the motor-speed control proposed for the DSCC-based drive system can enhance the start-up torque by a factor of three under the same ac-voltage fluctuation. Several start-up waveforms show stable performance from standstill to middle speed with different load torques.
- Published
- 2014
26. Experimental Verification of a Modular Multilevel Cascade Inverter Based on Double-Star Bridge Cells
- Author
-
TITICHAIWORAKORN, N, THITICHAIWORAKORN, NUNTAWAT, Hagiwara, Makoto, and Akagi, Hirofumi
- Subjects
Engineering ,business.industry ,Converters ,Modular design ,Grid ,Industrial and Manufacturing Engineering ,Control and Systems Engineering ,Cascade ,Modulation ,Electronic engineering ,Inverter ,Electrical and Electronic Engineering ,business ,Pulse-width modulation ,Voltage - Abstract
A modular multilevel cascade inverter based on double-star bridge cells (MMCI-DSBC) is expected to be one of the next-generation medium-voltage pulsewidth modulation (PWM) inverters intended for grid connections. This inverter is formed by six modular arms, each of which consists of a cascaded stack of multiple full-bridge converters. The DSBC is different from the traditional two-level PWM inverter in that the ac voltages are independent of the dc link voltage. Hence, the DSBC is suitable for a grid-connected inverter with a time-varying dc link voltage. This paper describes the DSBC with a focus on its operating principles and performance. The validity of the inverter is confirmed by experiments using a three-phase, 200-V, and 10-kW downscaled system.
- Published
- 2014
27. Overvoltage Mitigation of Inverter-Driven Motors With Long Cables of Different Lengths
- Author
-
Hirofumi Akagi and Itaru Matsumura
- Subjects
Engineering ,Computer science ,business.industry ,Electrical engineering ,Inductor ,Industrial and Manufacturing Engineering ,Electromagnetic interference ,law.invention ,Control and Systems Engineering ,Overvoltage ,law ,EMI ,Object-relational impedance mismatch ,Electronic engineering ,Inverter ,Adjustable-speed drive ,Electrical and Electronic Engineering ,Resistor ,business ,Electrical impedance ,Induction motor ,Voltage - Abstract
This paper presents an intensive discussion on an overvoltage appearing at the motor terminals of an adjustable-speed drive that consists of a voltage-source pulsewidth-modulated inverter, an induction motor, and a three-phase symmetric long cable. It describes a design procedure for a simple passive electromagnetic-interference filter based on parallel connection of an inductor and a resistor, which is intended for mitigating the overvoltage at the motor terminals. The modeling of the cable and the motor is characterized by focusing on the natural frequency or ringing frequency inherent in the cable used, which is inversely proportional to cable length. Impedance mismatch at the inverter and motor terminals causes the overvoltage that may reach double the inverter dc-link voltage. The effectiveness and validity of the simple design procedure of the filter are confirmed on the 400-V 15-kW experimental system with either a 100- or 200-m-long cable, as well as on computer simulation based on the modeling of the cable and the motor.
- Published
- 2011
28. Estimation of a Multimass System Using the LWTLS and a Coefficient Diagram for Vibration-Controller Design
- Author
-
Y. Yoshioka and Tsuyoshi Hanamoto
- Subjects
Closed-loop transfer function ,Engineering ,business.industry ,System identification ,Servo control ,Vibration control ,Servomotor ,time delay ,Transfer function ,Industrial and Manufacturing Engineering ,multimass mechanical system ,Control and Systems Engineering ,Control theory ,Control system ,Mechanical resonance ,Electrical and Electronic Engineering ,business ,system identification - Abstract
Vibration caused by mechanical resonance and time delay caused by signal detection and transmission degrade the control performance of a servo controller for a multimass mechanical system. A precise numerical model that represents resonance characteristics and time delay is necessary to design a desired control system. This paper presents an identification method using the iterative process of the linearized and weighted total least-squares method. The proposed method derives a transfer function without any prior knowledge of resonance characteristics and time delay. The order of the transfer function is determined with a coefficient diagram that shows coefficients of the denominator of the transfer function. Identification results with an experimental setup are shown to demonstrate the performance of the proposed method. A velocity servo controller with vibration-suppression control is designed with the transfer function, and control performance is verified with the experimental setup to validate the transfer function.
- Published
- 2008
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