Theory Of Synchronous Machines Research Articles

Development of method to design end-face synchronous motors made of amorphous steel using digital twin technology

Modern technologies of generative design and digital twins of electrical devices are based on the use of field models, as a rule, three-dimensional ones. Also, it is possible to solve design problems and to simulate accurately electrical machines and devices based on a set of 2D models of physical fields. Application of automatically generated field models in modern systems of engineering analysis during the design and optimization of electrical machines and devices makes it possible to get rid of many assumptions and outdated empirical and semi-empirical dependencies, as well as to reach a new methodological level of design theory, characterized by a unified approach to the calculation of various devices. Therefore, the purpose of this article is to develop a methodology to design a synchronous motor of an atypical design, based on the use of two-dimensional models of a stationary magnetic field at different design stages and allowing a solution to be obtained even in the absence of preliminary studies and recommendations. The finite element method is used implemented by means of the EMLib library (author's development), which allows calculating magnetic fields in a 2D formulation. Also, methods of the theory of synchronous machines and object-oriented programming in VBA in the MSExcel environment are used. Elements of digital twin technology and generative design are used while developing the methodology and design system. A method to design an end-face synchronous motor has been developed using automatically generated set of field models at the stages of choosing the height of a permanent magnet, calculating the parameters of an equivalent circuit, and an angular characteristic. Based on the popular MSExcel package, a system to design an end-face synchronous motor has been developed. The EMLib library has been implemented into the system, it allows using the results of calculating the magnetic field in the key design operations. The end-face synchronous motor has been designed and tested on the base of the developed system. The results of the research can be used during the development of methods to design electrical machines and devices of arbitrary, including non-standard design, for which approved algorithms for engineering analysis do not exist.

Research of Brushless Doubly-Fed Generator for Grid-Connection and Power Control

To reliably realize the grid-connection generating of brushless doubly-fed machine (BDFM), this paper firstly focuses on some essential issues, such as amplitude, frequency and phase of power winding voltage; the control of active and reactive power. Deducing the control method of power winding voltage amplitude, frequency and phase based on basic electrical machine principle. Referring synchronous machine theory, the modulation principle of active and reactive power for BDFM is obtained. Then, the connection progress to grid is researched by setting up the control platform based on DSP. The experimental results show that the amplitude, frequency and phase of power winding voltage are effectively controlled and the active and reactive power could be regulated when adopting the decoupled voltage control strategy. This control method provides a practical realization manner in the application of wind power generation and so on.

Starting of three-phase reluctance motors connected to a single phase supply

An analysis of the starting process of a three-phase reluctance motor when fed from a single-phase supply is presented. This analysis is aimed, mainly, at the determination of the variations in the different machine parameters as it pulls into synchronism. Special attention is given to the calculation of both the positive and negative sequence impedances. These impedances play an important role in the proper selection of the phase converter capacitance needed for ensuring satisfactory operation. For this purpose, the symmetrical component concept along with classical synchronous machine theory have been effectively employed. The devised mathematical model could also help in studying the asynchronous operation of synchronous machines when fed from either three-phase or single-phase power supplies. The effect of the value of the selected phase converter capacitance on the performance of the reluctance motor during starting and normal running conditions is investigated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Synchronous machine stability using composite governor and voltage regulator models

Abstract Most designers neglect the effect of the governor loop when selecting a suitable voltage regulator transfer function and gain of a turbo-generator. However, with modern fast acting governors, this could lead to unwanted interloop interference and oscillations. This paper investigates the steady state and transient stability limits of such a synchronous turbo-generator using analogue governor and voltage regulator loops similar to those found on large machines (30 – 750 MW). It proposes a design technique which optimizes the gains of the two loops on the basis of maximum steady state stability. Results obtained by measurement on a special micro-machine laboratory simulation are presented. These agree closely with predicted values based upon the well-known two-axis theory of synchronous machines.

Thrust and normal forces in a segmented-secondary linear reluctance motor

The linear counterpart of a segmented-rotor reluctance motor is studied to assess the feasibility of its application in ground transportation. Reactance formulas for the segmented-rotor motor are adapted to the segmented-secondary linear motor, and its performance is calculated using the salient-pole synchronous-machine theory. A numerical example of a preliminary design and analysis is presented, and the pertinent characteristics of the linear reluctance motor for ground transportation are discussed.

Novel interpretation of synchro principles

This paper deals with a now interpretation of synchro principles. Approximate equations for currant and torque in a synchro may be established directly from synchronous machine theory. However, this analysis is built up from fundamental laws in order to establish a theory especially adapted to synchros. The investigation centres on obtaining the basic mathematical relations governing the electro-mechanical operation of a transmitter-receiver synchro pair. The aim ia to derive the synchronizing torque for the condition where the synchros remain at rest. In this condition implementation of the superposition principle can be made. The method used is to write a set of vector equations for the synchros with stator current represented by direct and quadrature axis quantities, using the applied rotor voltage as the axis of reference. Theso equations are used to determine the stator Current in terms of which the torque is expressed.

Nonlinear Theory of Synchronous Machines On-Load

The usual two-reaction theory of synchronous machines yields results that neglect to take saturation into account. Based on a method developed in a companion paper [1], the radial airgap induction is found in synchronous machines when supplying balanced loads. The armature currents are considered to be distributed uniformly in the upper and lower layer of the armature windings. The partial differential equations, the boundary conditions, and the method of solution are reviewed. Numerical results are obtained for a 2750 kVA, 2300 V, 60 c/s, three-phase alternator at seven different internal power-factor angles. Calculated results compare well with tests.

Rotating-field theory and general analysis of synchronous and induction machines

The two-reaction theory of synchronous machines as developed by Blondel, Doherty, Nickle, Park and others is well known. The present paper attempts to develop the rotating-field theory of synchronous and induction machines as an important alternative to the two-reaction theory. The general analysis includes analysis of rotating machines under steady-state, transient-state and hunting conditions. Rotating reference frames are introduced. The new components, known as the forward and backward components, or f and b components, are then simply correlated to the direct and quadrature components, or d and q components. By use of the f and b components, it is shown that any external network and transmission line with lumped or distributed constants can be connected to a synchronous machine. This forms the basis of interconnection between synchronous and induction machines. A steady-state vector diagram of a salient-pole synchronous machine is given. Transient solution of short-circuit current and torque follows. An equivalent circuit for the same machine with direct- and quadrature-axis excitation is derived, and a 6-terminal network is developed for transient studies. The induction machine is similarly analysed with respect to its own rotor or with respect to a synchronously rotating reference frame. Interconnection of synchronous and induction machines is then possible for steady-state as well as transient studies. The hunting circuit involving one synchronous machine and a load is developed, based on Kron's uniformly rotating reference frame instead of the Blondel-Park reference frame. Hunting circuits for two rotating machines are developed, based on simple relations in absolute differential calculus. A number of instantaneous torque expressions are developed from the tensorial point of view. New expressions are given in terms of armature currents and flux linkages or their components.

Transient analysis of synchronous machines

The paper reviews the transient theory of synchronous machines and sets out the two-reaction transformation in matrix notation. The advantages of the matrix-transformation theory and the Laplace- transform method are demonstrated. It is shown that Park's transformation is equivalent to a change from a synchronous machine to a d.c. machine with brushes in the direct and quadrature axes and, in addition, an independent stationary zero- sequence circuit. An equivalent circuit is established for this d.c. machine (metadyne) and it is evident that transient fault-currents of a synchronous machine are intimately connected with those of a d.c. machine. Solutions are given for transient currents and torque.

The quadrature synchronous reactance of salient-pole synchronous machines

Advances in the theory of synchronous machines have created a number of reactance constants, and improvements in theory have led to continual refinements in methods of calculation and test. This paper presents an improvement in the calculation of the quadrature synchronous reactance, compares calculated with test results, and discusses four methods of test, one of which is an improvement in simplicity and ease of accomplishment over methods of test presented previously.

The Quadrature Synchronous Reactance of Salient-Pole Synchronous Machines

Advances in the theory of synchronous machines have created a number of reactance constants, and improvements in theory have led to continual refinements in methods of calculation and test. This paper presents an improvement in the calculation of the quadrature synchronous reactance, compares calculated with test results, and discusses four methods of test, one of which is an improvement in simplicity and ease of accomplishment over methods of test presented previously.

Extension of 2-reaction theory to multiphase synchronous machines

An extension of the 2-reaction theory of synchronous machines as developed by R. H. Park is given in this paper for machines with any number of phases.

Two-reaction theory of synchronous machines with any balanced terminal impedance

R.H. PARK <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1, 2, 3</sup> has presented a general analysis of salient-pole synchronous machines <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> in terms of direct, quadrature, and zero axis quantities. This analysis is very well adapted to the case of a machine with balanced series inductance and resistance in the armature circuit, but requires modification for any other terminal impedance. S. B. Crary <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> has recently extended the method of Park to include the effects of balanced armature circuit capacitance. In the present paper the same method of analysis is further extended to include the effects of any balanced impedance network connected to the armature terminals. Every concept (impedance operators, per-unit quantities, d and q axis quantities, etc.) of the previous synchronous machine theory is preserved unchanged in this extended theory, and every problem solvable by the previous theory is now susceptible to an exactly similar solution in the extended case. Such problems are, e.g.: 3-phase short circuit, sudden application or change of load, self-excitation, asynchronous operation, hunting, pulling into step, any prescribed change of field or armature voltage, torque under any of the conditions given above.

Two-reaction theory of synchronous machines

Discussion and author's closure of a paper by S. B. Gary published in the January 1937 issue, pases 27–31, and presented for oral discussion at the synchronous machinery session of the winter convention, New York, N.Y., January 27, 1937.

Contributions to synchronous machine theory

Discussion and author's closure of a paper by A. S. Langsdorf published in the January 1937 issue, pages 41–48, and presented for oral discussion at the synchronous machinery session of the winter convention, New York, N. Y., January 27, 1937.

Two-reaction theory of synchronous machines

An extension of the 2-reaction theory of synchronous machines as developed by R. H. Park is given in this paper for machines having capacitance in the armature circuit. General equations for predetermination of the performance under certain abnormal conditions of machines having balanced 3-phase capacitance in the armature circuit are presented.

Two-Reaction Theory of Synchronous Machines

An extension of the 2-reaction theory of synchronous machines as developed by R. H. Park is given in this paper for machines having capacitance in the armature circuit. General equations for predetermination of the performance under certain abnormal conditions of machines having balanced 3-phase capacitance in the aramture circuit are presented.

Contributions to Synchronous-Machine Theory

In this paper the 2-reaction theory of synchronous machines is extended, for steady-state conditions, to present some new deductions apparently not previously known.

Two-reaction theory of synchronous machines — Part II

RESULTS of certain mathematical investigations which have been found to be of practical use in the analysis of problems involving the transient behavior of interconnected machines are presented in this paper.

Calculation of Synchronous Machine Constants- Reactances and Time Constants Affecting Transient Characteristics

Recent advances in the theory of synchronous machines have introduced a large number of new constants. The method of symmetrical components requires sequence reactances, and an accurate theory of transients requires transient and subtransient reactances and time constants. Most of the published discussion on the constants has been concerned with the application, rather than the calculation of values. In this paper, all of the most significant constants are calculated, except the subtransient time constant. A general method of calculation is discussed in which the reactances are accurately resolved into components. Comparisons of test and calculated values are given. The formulas for salient-pole machines and turbine generators are given in Appendixes A and B. The principle of superposition is applied to resolve accurately the reactances into components which can be readily calculated. The induced currents in the field and additional damping circuits are accounted for simply by applying the constant interlinkage theorem.