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Energy Conversion, IEEE Transactions on

Issue 3 • Date Sept. 1991

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Displaying Results 1 - 25 of 32
  • Two-axis model development of cage-rotor brushless doubly-fed machines

    Page(s): 453 - 460
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    A two-axis model of a cage-rotor brushless doubly-fed machine (BDFM) which is suitable for machine and BDFM drive system dynamics studies is presented. The technique enables the two-axis model to be derived from a detailed model recently developed for investigation of design aspects of the machine. Unlike the conventional approaches to self-cascaded machines analysis, this method permits analysis of the machine characteristics in both dynamic and steady state conditions, and also facilitates machine and drive system design by directly correlating machine performance with machine structure and parameters. The approach allows the machine parameters to be calculated from machine geometry and developed into the model parameters.<> View full abstract»

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  • Losses influenced by third-harmonic flux in induction motors

    Page(s): 461 - 468
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    The trend toward increasing flux density in modern induction motors results in the increase of third-harmonic flux in the magnetic paths. The effects of third-harmonic flux on energy losses in induction motors are discussed. The shapes of flux distributions in various sections of an induction motor are interrelated. The most saturated section normally has a flattened shape of flux density distribution. The effects of the shapes of flux density distribution on losses are compared from the third-harmonic flux standpoint. The losses influenced by the third-harmonic flux may be controlled through lamination punching designs and winding connections View full abstract»

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  • A prototype expert system for failure cause analysis in closed feedwater heaters

    Page(s): 356 - 360
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    A joint effort to develop an expert system dealing with failure cause analysis in closed feedwater heaters is described. A summary of the development of the prototype system is presented, and its use in determining the cause of a tube failure in a feedwater heater is described. A prototype of the expert system has been developed and demonstrated View full abstract»

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  • Effect of saturation on the steady-state stability of a synchronous machine connected to an infinite bus system

    Page(s): 514 - 521
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    A synchronous machine model that includes the effect of the saturated reactances the cross-magnetizing phenomenon is presented. This model is used to study the steady-state stability of a synchronous machine connected to an infinite bus system. These studies show that the effect of saturation is noticeably large and depends mainly on the cross-magnetizing effect. The results obtained by this model are found to be in good agreement with those obtained from the experimental results View full abstract»

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  • Methodology for on-line incipient fault detection in single-phase squirrel-cage induction motors using artificial neural networks

    Page(s): 536 - 545
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (844 KB)  

    A novel approach for online detection of incipient faults in single-phase squirrel-cage induction motors through the use of artificial neural networks is presented. The online incipient fault detector is composed of two parts: (1) a disturbance and noise filter artificial neural network to filter out the transient measurements while retaining the steady-state measurements, and (2) a high-order incipient fault detection artificial neural network to detect incipient faults in single-phase squirrel-cage induction motors based on data collected from the motor. Simulation results show that neural networks yield satisfactory performance for online detection of incipient faults in single-phase squirrel-cage induction motors. The neural network fault detection methodology presented is not limited to single-phase squirrel-cage motors (used as a prototype), but can also be applied to many other types of rotating machines, with the appropriate modifications View full abstract»

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  • Analysis of the waveform-detection technique for indirect roto-position sensing of switched reluctance motor drives

    Page(s): 476 - 483
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    A sensing technique that monitors rotor-position indirectly by monitoring the phase current waveform is evaluated. Computer simulations showing the effects of back-EMF on phase current rise and fall-times are presented. A control circuit for current-waveform-based rotor-position detection has been implemented using hard-wired digital circuits. Torque-speed and system efficiency characteristics resulting from the application of the method to a 4 kW, four-phase SR motor with IGBT drive are also presented View full abstract»

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  • Suboptimal design of hydroturbine governors

    Page(s): 438 - 444
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    A state space method for the design of turbine governors in hydro power plants with Kaplan turbines is presented. The design is based on the suboptimal regulator problem solved by the use of projective controls. A design procedure that permits the design of multivariable static and low order dynamic hydroturbine governors is proposed. It provides an organized way of choosing the governor structure and the tuning of its parameters. A case study is presented to illustrate the proposed design method and to demonstrate the extensive applicability of the suboptimal solution and its merits as compared to conventional governors View full abstract»

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  • Speed and power factor controller for AC adjustable speed drives

    Page(s): 469 - 475
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    The speed and power factor of an adjustable speed slip power recovery drive are controlled in order to optimize the operation. This is accomplished by means of a variable-voltage-variable-frequencies power converter. The function of the digital controller of the power converter is to provide the online speed and power factor regulation. The hardware and software are described. This scheme has an accurate voltage output with very low harmonic content, a good resolution for the phase angle regulation and the frequency control with the possibility of range extension View full abstract»

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  • Test results for transient excitation boosting at Grand Coulee

    Page(s): 367 - 372
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    Transient excitation boosting (TEB) hardware is discussed, and its design and installation are described. The test results from the hardware commissioning on each generator type are addressed. The results show that an 8% boost in terminal voltage results in about a 50% change in reactive power loading and about a 10% change in real power with the classical high-frequency damped oscillations which are typical of a step response View full abstract»

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  • Synchronous-machine standstill frequency-response test data analysis

    Page(s): 564 - 571
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    Frequency response methods used in the development of linear transfer functions representing nonlinear processes are extended to standstill frequency response tests for synchronous machines, thus providing an independent check on the equivalent circuit method of IEEE Standard 115A. By iterative subtraction of three separate transfer function elements from the Bode plot of the experimental data an overall transfer function can be synthesized, leaving a small residue of Bode-plotted data that represent irregularities due to nonlinearities, noise, or erroneous data. Suggested limits for the range of test frequencies and the magnitudes of residual transfer function are given View full abstract»

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  • Thermoelastic effects on slipring surface leading to brush vibrations

    Page(s): 522 - 528
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    A novel interpretation of the brush vibration phenomenon is presented for current collection systems consisting of carbon brushes and steel sliprings. For the investigation of this phenomenon, a mechanical model with a rigid brush was used, and the thermal deformation of the slipring surface due to the losses generated by the vibrating brush was taken into consideration. The calculations show that at certain parameter configurations the brush vibration reinforces the thermal deformation and the closed-loop system becomes unstable, leading to pronounced brush vibration referred to as regenerative brush chatter. Measurements of the slipring surface temperature confirm this theory View full abstract»

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  • A state-space pressure and speed sensing governor for hydrogenerators

    Page(s): 414 - 418
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The use of the pressure signal for speed control of hydrogenerators is investigated. This is done by first analyzing and modeling the plant, assuming an isolated, resistive load. A set of governor gains that give an optimal response to a change in load level using speed feedback is then found. With this response as a benchmark, various methods are analyzed and implemented, utilizing the pressure signal, to improve the response of the system. A state-space observer, designed to attenuate noise on the pressure signal, is discussed. Results show that an observer-based controller using all states as input, as compared to a PID controller, improves the transient response of hydrogenerators, is effective at filtering out the noise on the pressure signal and is more robust to both steady-state pressure and plant parameter variations View full abstract»

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  • Development of a PC-based data acquisition system for performance monitoring on an 81 megawatt steam cycle electric power generating unit

    Page(s): 426 - 431
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A computer-based performance monitoring system has been successfully developed and implemented on an 81 MW steam cycle generating unit. The instrument, data acquisition, computer, and software requirements for the system are discussed. This PC-based system was designed in such a manner that it is transparent to the unit's existing control scheme. Data from this system permits the setting of operating limits to avoid ongoing problems of turbine blade damage View full abstract»

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  • Structural modeling of small and large induction machines using integral manifolds

    Page(s): 529 - 535
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    Structural dynamics of small and large induction machines are investigated using integral manifolds and are shown to be markedly different. Whereas the dominant behavior in small machines is characterized by a well-known first-order speed model, the corresponding behavior in large machines is characterized by a novel first-order voltage model. Nonlinear simulations and eigenvalue analyses illustrate the validity of the structural models developed View full abstract»

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  • Design of a 5 MW, 9000 V switched reluctance motor

    Page(s): 484 - 491
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    A large, high-voltage switched reluctance motor that benefits from the more reliable concentration stator winding with regard to switching surges is presented. The easy-to-build rotor construction enhances reliability. Details of the high-voltage winding are presented, together with performance predictions. Prospects for even larger machines are discussed View full abstract»

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  • Maximum slew-rate governor control for impulse turbines

    Page(s): 419 - 425
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    A deflector bang-bang and speed derivative methodology for controlling impulse turbine transients is developed. The control was implemented in a linear simulation to demonstrate its effectiveness in controlling load torque perturbations. The proposed controller strategy is implemented in a nonlinear simulation. The design was found to significantly reduce turbine off-speeds and nominal operating point settling times in both simulations View full abstract»

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  • Dynamic simulation of brushless doubly-fed machines

    Page(s): 445 - 452
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    Dynamic and steady-state models for the simulation of the performance of experimental brushless doubly-fed machines (BDFM) are presented. The dynamic simulation results are obtained using a two-axis representation which has been developed from a detailed machine design model. In turn, it is shown that several forms of steady-state equivalent circuit can be developed from the two-axis model for different specific modes of operation. Test data in dynamic conditions are compared with the predictions given by the two-axis model. It is concluded that these simplified models will provide adequate representation of full performance for control, stability, and scoping studies View full abstract»

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  • Stabilizing torsional oscillations using a hunt reactor controller

    Page(s): 373 - 380
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    Results of a study on the application of shunt reactors for the damping of torsional oscillations that occur in a power system containing series-capacitor compensation are presented. The IEEE Second Benchmark Model, system-1 is used to investigate the benefits of the utilization of modulated reactive power in suppressing unstable subsynchronous resonance (SSR) modal interactions. A set of shunt reactors is connected to the generator bus of the affected synchronous machine whose shaft is directly coupled to the turbine system of the benchmark model. In order to stabilize all the torsional modes, a unified approach based on modal control theory is proposed for the design of a shunt reactor controller, which is essentially a dynamic output compensator. To demonstrate the effectiveness of the damping enhanced by the proposed scheme, eigenvalue analysis for different loading conditions and sensitivity analysis for controller parameters are performed View full abstract»

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  • Optimum expansion planning of an unconventional generation system operating in parallel with a large scale network

    Page(s): 394 - 400
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    A package for the long-term optimal expansion planning of a generation system with renewable energy sources operating in parallel with a large-scale network is presented. The algorithm utilizes meteorological data, load demand data, and estimated economical parameters and determines the candidate plans for the expansion period. A forward dynamic programming algorithm is utilized to determine the optimal plan. Results from the application of the method to a local grid are presented View full abstract»

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  • Polarized film resolver for the control of permanent magnet synchronous machines

    Page(s): 560 - 563
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    The design of a three-phase sinusoidal output electrooptic resolver is presented. This resolver utilizes polarized films to provide variable attenuation of a light source. It generates a sinusoidal output voltage which is a function of the angular position of its shaft. A prototype of the sensor has been constructed and tested. It can be used to control an inverter to drive a permanent magnet synchronous machine. Uses include electric cars, industrial machine drives, and controllers for wind turbine systems View full abstract»

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  • Frequency measurement for use with a microprocessor-based water turbine governor

    Page(s): 361 - 366
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    A digital frequency measurement approach and its implementation for use in conjunction with a duplex fault-tolerant microprocessor-based governor for water turbines is described. The proposed approach has a wide measuring range, high resolution, and fast response. The circuitry and the software are simple. The interface to the generating plant is direct and simple. Due to the direct measurement of the frequency instead of speed, it can adapt to any plant without changes to either the hardware or the software. Results in an actual power system environment have proven that the proposed measurement technique can meet the requirements of speed control in electric power systems View full abstract»

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  • A fuzzy logic based stabilizer for a synchronous machine

    Page(s): 407 - 413
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    The application of a fuzzy logic controller to improve the stability of electric power systems is presented. The stabilizing signal is computed using the standard fuzzy membership function depending on the speed acceleration state of the generator in the phase plane. The required measurement is the speed deviation over two samples. The effectiveness of the proposed stabilizer is demonstrated by simulation studies for different operating conditions and disturbances View full abstract»

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  • Calculation of neutral voltage shift in LCI driven induction motors

    Page(s): 507 - 513
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    Load commutated inverter (LCI) drives are being used for adjustable speed control of induction motors and synchronous motors. It has been found that the motors and transformers connected to these drives are subjected to higher than normal voltage stresses to ground and premature failures of motors have been reported. This has been shown to be due to a voltage difference between the source side neutral voltage and the motor neutral voltage. This voltage is known as the neutral shift. This neutral shift voltage is added to the normal line to neutral or phase voltage causing a much higher than normal line or terminal to ground voltage stress in the ungrounded side of any DC linked AC converter. Voltages as high as 3.3 pu normal phase voltage may be seen for certain types of inverters. A method of determining the neutral shift voltage is presented. Results of a computer simulation of an LCI circuit and test results are presented to verify this analysis View full abstract»

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  • Analysis of transient forces in metal clad generator buses

    Page(s): 432 - 437
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    Transient short-circuit forces are analytically calculated in an arrangement of three parallel and coplanar busbars. Each is enclosed in a tubular, conducting, shell. Results can be used for the design of metal clad connection buses for large generators or similar uses. Shells made of aluminium with 10 mm thickness reduced the forces applied on the phase conductors by a factor of 20 or more as compared with arrangements without shells. Forces applied on a phase conductor and to the corresponding shell have same order of magnitude View full abstract»

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  • Dynamic response of power conditioning systems for superconductive magnetic energy storage

    Page(s): 388 - 393
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    The dynamic response of two power conditioning systems for superconductive magnetic energy storage (SMES) are presented. One power conditioning system is based on a hybrid current sourced inverter (CSI), the second is a combination of a DC chopper with a voltage sourced inverter (VSI). The response of both systems to a load change, a three phase fault, and start-up is presented View full abstract»

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Aims & Scope

The IEEE Transactions on Energy Conversion includes in its venue the research, development, design, application, construction, installation, operation, analysis and control of electric power generating and energy storage equipment (along with conventional, cogeneration, nuclear, distributed or renewable sources, central station and grid connection). The scope also includes electromechanical energy conversion, electric machinery, devices, systems and facilities for the safe, reliable, and economic generation and utilization of electrical energy for general industrial, commercial, public, and domestic consumption of electrical energy.

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Meet Our Editors

Editor-in-Chief
Juri Jatskevich
University of British Columbia