Stability Of Synchronous Machine Research Articles

Stability of synchronous machine with divided-winding rotor

To deal with a divided-winding rotor (d.w.r.) synchronous machine in which the two field windings are not located on the rotor axes and may not have equal numbers of turns, an equivalent machine is introduced with field windings on the direct and quadrature axes. The steady-state stability calculations are carried out by applying the Nyquist criterion to the linearised equations for small oscillations of a system with more than one feedback regulator. This investigation is followed by using the nonlinear differential equations and a digital computer to find the transient response after a change in the tieline impedance. The calculated results are confirmed by experiments carried out on the micromachine equipment at Imperial College, London. The alternatives studied included systems using one regulator at a time, both regulators together and various transfer functions for each regulator. The main conclusion is that the angle regulator stabilises the voltage regulator and has a major influence on the stability of the system; hence the voltage-regulator gain can be varied over a wide range.

Stability of synchronous machine with divided-winding rotor

Stability of synchronous machine with divided-winding rotor

Concepts of Synchronous Machine Stability as Affected by Excitation Control

The phenomena of stability of synchronous machines under small perturbations is explored by examining the case of a single machine connected to an infinite bus through external reactance.

Comment on ‘An Application of Lyapunov Method to Synchronous Machine Stability by Fallside and Patel’

ABSTRACT The variable gradient method was used to generate a Lyapunov function for the system of first-order differential equations describing the synchronous machine, and Fallside and Patel (1966) used this V-function to estimate the domain of stability of the system. This particular problem, as mentioned by Barbashin (1961), was solved by Yanko-Trinitsky (1958). Trinitsky, according to Barbashin, used the ‘ separation of variables ’ method to generate his V-function, and in his analysis, he included second-order terms, which is more general than the problem solved by Fallside and Patel (1966).

Steady-state stability of synchronous machines with augmented rotor resistance

An analysis of the steady-state stability of round-rotor synchronous machines, which was restricted to operation with a relatively large rotor time constant, is extended to include operation with a small time constant. Experimental results show qualitative agreement with the analysis, but a weakness in it is also revealed.

Erratum: Steady-state stability of variable-frequency synchronous machine drives

Erratum: Steady-state stability of variable-frequency synchronous machine drives

Steady-state stability of variable-frequency synchronous machine drives

An analysis of the steady-state stability of round-rotor synchronous machines is shown to be valid over a wide range of supply frequency. Good agreement is reached with experimental results employing a d.c. link invertor over the frequency range 12.5–75 Hz, and a comparison is made with experimental results employing a sinusoidal supply.

Discussion on “Effect of excitation regulation on synchronous-machine stability”

Discussion on “Effect of excitation regulation on synchronous-machine stability”

Effect of excitation regulation on synchronous-machine stability

Effect of excitation regulation on synchronous-machine stability

On the Application of the Lyapunov Method to Synchronous Machine Stability†

ABSTRACT The Lyapunov stability method is applied to two problems in the dynamic behaviour of round-rotor synchronous machines. In one case analytical results of a sufficient nature are obtained from an approximate mathematical model which explain the dependence of the self-oscillation of a machine on the stator impedance and the rotor excitation, and good agreement is found with experimental results. The other case is the ‘two-machine’ problem of two synchronous machines connected by a transmission line subject to a fault. Using the complete set of Park's equations an analytical expression is obtained for the transient stability surface. In general this is of a fairly weak sufficient nature but in a restricted region of the state-Space it gives a close agreement with the computed region of stability. The dynamic equations of the machines involve trigonometrieal functions of the state variables, and in this study the variable gradient method of Schultz and Gibson has been found useful for generating Lyapu...

Effect of excitation regulation on synchronous-machine stability

The paper records a detailed study of the effect of a voltage regulator on the stability of an alternator connected through a reactance to an infinite bus. The stability is analysed by means of Nyquist loci calculated for the transfer functions of alternator and regulator. The accuracy and speed of response of the system are also considered. The first part of the paper considers a simple regulator with proportional feedback, and it is shown that such an ideal regulator can extend the region of steady-state stability to a point corresponding to the maximum of the transient power-angle curve.Practical regulators are classified according to the nature of their transfer functions. The analysis provides a means of predicting their behaviour and explains how they affect the stability, accuracy and response. The effect of delay elements, integrator elements and derivative elements in the regulator is considered particularly; e.g. a buck-boost exciter, which effectively introduces an integrator element, gives good accuracy but less satisfactory response, and has a limited effect on stability, and a derivative regulator which gives rapid response and a large extension of the stability region, but has limited accuracy.Experiments performed on a model machine with various simulated regulators agreed well with the computed results. The computations allowed fully for the system parameters, including alternator resistance and alternator damping.

Steady-State Stability of Synchronous Machines as Affected by Angle-Regulator Characteristics

Steady-State Stability of Synchronous Machines as Affected by Angle-Regulator Characteristics

Steady-state stability of synchronous machines as affected by voltage-regulator characteristics

Steady-state stability of synchronous machines as affected by voltage-regulator characteristics

Steady-state stability of synchronous machines as affected by voltage-regulator characteristics

Steady-state stability of synchronous machines as affected by voltage-regulator characteristics

Steady-State Stability or Synchronous Machines as Affected by Voltage-Regulator Characteristics

STEADY-STATE stability of synchronous machines is an old subject, and the fact that voltage regulators may on occasion increase the stability limit is more or less well known.1 The present paper, however, aims to contribute to the knowledge of the subject by:

Abridgment of stability of synchronous machines: Effect of armature circuit resistance

Abridgment of stability of synchronous machines: Effect of armature circuit resistance

Stability of large power systems

The paper deals with the stability, voltage control, and power limits of electric- power systems and machines?more particularly, large alternating-current systems. The subject is dealt with in the following sequence :? Definition of stability. Stability and power limits of simple circuits. Larger power lines. Artificial stability of power lines. Natural stability and power limits of alternators and synchronous machines. Short-circuits and transient stability of alternators. Internal reserve of excitation of synchronous machines. Artificial stability of alternators. Stability of exciters. Types of electric power supply systems. Feeders and transmission lines and their voltage control. The conclusions reached are that synchronous machines can be made sufficiently stable for all the usual purposes of power supply, and that the power limit and voltage regulation of transmission circuits depend principally on their series reactance.