Michel Poloujadoff

POWER FLOW ANALYSIS AND EFFICIENCY OPTIMIZATION OF A DOUBLY FED SYNCHRONOUS MACHINE

ABSTRACT This paper deals with the energy balance of the doubly fed synchronous machine (DFSM). The proposed method is based on the principle which consider that the electro–mechanical conversion takes place between stator circuits and the machine shaft, so that the electrical power applied to rotor circuits is taken as a command. From this point of view, the study stresses are: Stability, A low ratio of the rotor command referred to the converted energy, High efficiency. Results are presented in the rms value of rotor applied voltage (V2a) – angle between the stator and the rotor voltages vectors (5) plane. We have found, when we vary the slip (s), that the high efficiency areas move in such way that the ratio of s over V2a remains constant (which means a constant rotor flux).

Modelling and Identification of Parameters of Saturated Induction Machine Operating Under Motor and Generator Conditions

This work presents modelling and parameters identification of a saturated induction machine. Different algorithms of nonlinear optimization were used in this work. The new model which was elaborated, allows us to carry out a good parameters identification from the measurements obtained from the two modes of operating as motor and as generator. This model has two different saturation reactances. One can be identified from motor and the other from generator operation. An interpretation of the reactance saturation is done.

Introduction to an improved modeling of electric lines propagation

The authors suggest an improvement to transient algorithms based on the simulation of a ladder network. This improvement is obtained by adding a negative capacitor in parallel with the series inductances. This improves both the harmonic and the transient responses without increasing the size of the matrices.

Stability analysis of a non-Park-transformable electrical machine model

The stability properties of a linear or linearized, periodically-varying model of an electrical machine can be studied as a function of speed via direct computation of the monodromy matrix, from which the characteristic exponents can be determined. The machine used as an example in this paper is the nonsalient-pole damped alternator described in [1], and also used as an example in [2]. The characteristic exponents are obtained in [1] by a completely different method. Although round-off error interferes with the computation of the fast (and hence rather unimportant) exponents at very low speeds, the monodromy computation provides a straightforward method for determining the characteristic exponents of the periodically-varying system. A conjecture in [2] on the asymptotes of the exponents in the low-speed limit is proved and extended here, and results in [2] on the high-speed limit are reformulated in the setting of classical averaging theory.

A Numerical Example of Alternator Model Reduction to Be Given in a Classroom

The authors give a numerical example of a stability study of an alternator connected to an infinite bus through a transmission line. Possible reductions of the model are carefully considered. This paper is intended to be the basis of exercises submitted to students for a computer solution.

EXPERIMENTAL DETERMINATION OF MACHINE CHARACTERISTICS FOR A DOUBLE STAR ARMATURE SYNCHRONOUS MACHINE

ABSTRACT In a recent paper, we have developed a two-axis d-q model for a double star armature synchronous machine. In this model we have defined new operational impedances and time constants corresponding to the mutual interaction between the stator windings. In this paper we present a method,that we developed, which permits us to determine experimently all the machine characteristics and model parameters.

DESIGNING 2 POLE AND 2/4 POLE WINDINGS BY THE SIMULATED ANNEALING METHOD

The object of the present paper is to explore the possibility of using simulated annealing procedures to determine multi-speed three phase windings. It is limited to the very simple case of p/2p polarities. The program has yielded the very well known solutions; thus, research may proceed towards more difficult problems.

COMMUTATION OF D.C. MACHINES WITHOUT COMMUTATION POLES BY MEANS OF EXTERNAL ELECTRONIC DEVICES

In DC machines commutation may be performed inside the rotor by means of commutating poles. This is the classical way which gives good performances in normal working but presents some limits for unsteady running conditions. This paper deals with a special commutation process, from the outside of rotor, which is achieved without commutating poles through an electronic circuit connected with the commutator. The device is easily drived from the actual rotor position and is able to adjust commutation to miscellaneous conditions. Besides driving versatility, such process allows the suppression of commutating poles whose size is about 20 per cent of main poles. The possible weight reduction is attractive. The paper presents theory and experiment on a classical DC machine with a lightly altered commutator at a level of some kW.

A Study of Unsymmetrical Short Circuit of Unsaturated Salient Pole Damped Synchronous Machine

It is shown that the study of salient pole synchronous machines is much more difficult than the study of uniform air gap synchronous machines. Indeed saliency leads to high order recurrent relations, and to singular matrices which prevent the use of methods already published. Nevertheless, the Floquets reference frame has been entirely determined. A numerical example is given.