Preface.Basic Principles for Electric Machine Analysis.Direct--Current Machines.Reference--Frame Theory.Symmetrical Induction Machines.Synchronous Machines.Theory of Brushless dc Machines.Machine Equations in Operational Impedances and Time Constants.Linearized Machine Equations.Reduced--Order Machine Equations.Symmetrical and Unsymmetrical 2--Phase Induction Machines.Semicontrolled Bridge Converters.dc Machine Drives.Fully Controlled 3--Phase Bridge Converters.Induction Motor Drives.Brushless dc Motor Drives.Appendix: Trigonometric Relations, Constants and Conversion Factors, and Abbreviations.Index.

Analysis of electric machinery and drive systems

Starting with the basic assumption of no saturation or hysteresis, and with distribution of armature phase m. m. f. effectively sinusoidal as far as regards phenomena dependent upon rotor position, general formulas are developed for current, voltage, power, and torque under steady and transient load conditions. Special detailed formulas are also developed which permit the determination of current and torque on three-phase short circuit, during starting, and when only small deviations from an average operating angle are involved. In addition, new and more accurate equivalent circuits are developed for synchronous and asynchronous machines operating in parallel, and the domain of validity of such circuits is established. Throughout, the treatment has been generalized to include salient poles and an arbitrary number of rotor circuits. The analysis is thus adapted to machines equipped with field pole collars, or with amortisseur windings of any arbitrary construction. It is proposed to continue the analysis in a subsequent paper.

Two-reaction theory of synchronous machines generalized method of analysis-part I

The effectiveness of an analog computer in studying the performance of induction machinery is demonstrated with computer results which show the dynamic behavior of 2-phase and 3-phase machines during balanced and unbalanced operation. The computer simulation for these various modes of operation is conveniently obtained from the equations which describe the symmetrical induction machine in an arbitrary reference frame. Of particular interest is the representation which is used to simulate the opening and closing of a stator phase. This simulation would be useful in studying the performance of the induction machine when used in conjunction with electronic switching devices. The examples which are given can be used directly, or in a slightly modified form, to study various practical problems. Also, these examples should serve as guideposts in selecting the best reference frame or the best combination of reference frames to be used in the computer simulation of systems which have more than one machine.

Simulation of Symmetrical Induction Machinery

This article reviews techniques for the control of wind turbines during power production. Pitch control is used primarily to limit power in high winds, but it also has an important effect on structural loads. Particularly as turbines become larger, there is increasing interest in designing controllers to mitigate loads as far as possible. Torque control in variable-speed turbines is used primarily to maximize energy capture below rated wind speed, and to limit the torque above rated, but it can also be used to reduce certain loads. The design of the control algorithms is clearly of prime importance. Additional sensors such as accelerometers and load sensors can also help the controller to achieve its objectives more effectively. By controlling the pitch of each blade independently, it is also possible to achieve important further reductions in loading. It is important to be able to quantify the benefits of any new controller. Although computer simulations are useful, field trials are also vital. The variability of the real wind means that particular care is needed in the design of the trials. Copyright © 2003 John Wiley & Sons, Ltd.

Wind Turbine Control for Load Reduction

Preface. Notation. 1. Background. 2. Introduction to SIME. 3. Sensitivity Analysis. 4. Preventive Analysis and Control. 5. Integrated TSA&C Software. 6. Closed-Loop Emergency Control. 7. Retrospect and Prospect. Appendices. References. Index.

Transient Stability of Power Systems: A Unified Approach to Assessment and Control

Two Reaction Theory of Synchronous Machines

Until somewhat recently, synchronous machine theory has been satisfied with a relatively few characteristic constants, or reactances, in terms of which the behavior of machines has been calculated. Present theory, however, requires many more coefficients. There are now generally recognized two values each of leakage, synchronous, and transient reactance which correspond to the two symmetrical axes of magnetization of the armature current and which refer to balanced operation. Negative and zero phase-sequence reactances are also employed to determine operation under unbalanced conditions, and it is possible and desirable to distinguish other reactances. In view of the increasing complexity of the subject it is felt that a critical survey of it is in order and the object of the paper has been to provide that survey. The paper has been divided into two parts. Part I is descriptive, and treats the subject with regard to those factors which are important to application or operating engineers, and to designers. In particular, the major types of reactances which include the synchronous, transient, and phase-sequence reactances, are discussed. These quantities are defined and their methods of test outlined. It appears necessary to consider a second type of transient reactance, namely sub-transient reactance. Both reactances may be determined from short-circuit oscillograms as illustrated in the paper. A table is included which gives the numerical range of reactances for the various types of synchronous machines. Part II discusses the theoretical considerations, with a view to broadening and classifying existing conceptions of reactance.

The Reactances of Synchronous Machines

Under modern conditions of operation the ability of the component machines of a power system to hold in step during system disturbances has become of major importance in the choice of system layout and machine design. This situation has greatly stimulated activity in the study of the problems involved. This paper reviews the general problem in the light of recent analytical and experimental studies made by the authors. The subject matter of the paper is grouped according to the following headings: Part I reviews the factors affecting stability, including generator short-circuit ratio, voltage regulators, excitation systems, neutral impedance, governors, amortisseurs, intermediate condensers. Part II gives methods of calculating stability, under the following heads: preliminary calculations, idealized case of two machines, general case of two machines, extension to include more than two machines, simplified method of calculating tie lines. The appendixes include an example illustrating the method of calculation in a particular case.

System Stability as a Design Problem

Three papers on the general subject, ``Graphical Determination of Magnetic Fields,'' are being presented simultaneously to cover three phases of the subject: 1. Theoretical Considerations, 2. Comparison of Calculations and Tests, by E. E. Johnson and C. H. Green, 3. Practical Applications to Salient-Pole Synchronous Machine Design, by R. W. Wieseman. In the following paper, which is the first of this series, the authors have reviewed the history of the subject, hare briefly stated the ordinary rules for plotting magnetic flux in air and in current-carrying copper, have developed additional rules for checking the accuracy of field plots, and have given theoretical methods for mathematically calculating the distribution of field in certain cases commonly encountered in practise. The authors have called attention to the great value of the mathmatical work by the German engineer, Rogowski, and the graphical methods by the French engineer, Lehmann. These German and French articles contain the only extensive practical applications of the plotting of magnetic fields in current-carrying regions with which the present authors are familiar. Since it is much more difficult to plot fields in current-carrying regions, and since the majority of readers are less familiar with this phase of the subject, the greater part of the first paper, ``Theoretical Considerations,'' is devoted to a study of such fields.

R. H. Park

Papers

Two-reaction theory of synchronous machines generalized method of analysis-part I

Two Reaction Theory of Synchronous Machines

The Reactances of Synchronous Machines

System Stability as a Design Problem

Graphical Determination of Magnetic Fields Theoretical Considerations