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The paper seeks to present a methodology of computer simulation of 3D transient electromagnetic fields, losses and forces due to negative sequence currents in fragments of large synchronous turbogenerator rotors. The methodology allows for the preparation of initial data for further computations of thermal and mechanical behaviour of rotors.

The governing equations for 3D negative sequence transient electromagnetic fields with the Coulomb gauge using magnetic vector potential and scalar electric potential A, V – A are solved by the nodal finite element method in a Cartesian coordinate system moving synchronously with the rotor.

The presented methodology of 3D transient electromagnetic phenomena computation seems to be effective because the electromagnetic field in the rotor of a synchronous generator is generally three dimensional, and therefore 2D field‐computation approaches and software are not able to simulate intrinsically 3D electromagnetic processes in turbogenerator rotors.

Currently it is difficult to carry out accurate numerical simulation of 3D transient electromagnetic fields and therefore losses and forces within the whole structure of the rotor because of the resulting huge computational expenses. This paper is devoted to the finite element analysis of electromagnetic fields, losses and forces in separate structural parts of the rotor. As an example of practical utilization of the developed technique, the computer simulation of electromagnetic phenomena in junctions of nonmagnetic rotor slot wedges of a 300 MVA class synchronous turbogenerator is carried out.

The methodology can successfully be used during the design process of modern large synchronous turbogenerators.

This paper presents numerical analysis of intrinsically 3D transient electromagnetic phenomena in large turbogenerator rotors.

The finite‐difference discretization required to model accurately very small air gaps between ferromagnetic surfaces can be enormous. Provided the surrounding permeability is high, a simple representation of the air gap can be formulated within a finite‐difference equation, thus substantially reducing the number of nodes required. The method is applied to the determination of the force on a rectangular magnetic filler bar in the centre slot of the pole face of a turbogenerator rotor.

The paper seeks to present a methodology of computer simulation of coupled magneto‐thermo‐mechanical processes in various electrical engineering devices. The methodology allows determining their parameters, characteristics and behaviour in various operation regimes.

The mathematical model consisting of three equations describing magnetic field, temperature field and field of mechanical strains and stresses (or thermoelastic displacements) is solved numerically, partially in the hard‐coupled formulation.

The methodology seems to be sufficiently robust, reliable and applicable to a wide spectrum of devices.

At this stage of research, the hard‐coupled formulation of thermo‐mechanical (or thermoelastic) problems is still possible only in 2D.

The methodology can successfully be used for design of numerous machines, apparatus and devices from the area of low‐frequency electrical engineering ranging from small actuators to large synchronous generators.

Complete numerical analysis of coupled magneto‐thermo‐mechanical phenomena in electrical devices.

“Tribological Design — The Power Generation Industry”, was an invited paper presented at the 15th Leeds‐Lyon Symposium held in Leeds in 1988. A review of the proceedings published last autumn appeared in the last issue of Industrial Lubrication and Tribology. The permission of the publisher, Elsevier, Amsterdam, to reprint this article is gratefully acknowledged.

The armature slots produce flux density pulsations in the pole face and hence eddy current losses, the calculation of which has not been fully satisfactory to date. One consideration ignored is that, since the ac field in the pole face oscillates in the presence of a strong dc field, eddy currents are induced by a field whose mean value is at a point on the B/H curve dictated by the dc flux density so that the incremental permeability becomes important. In order to study this effect we require knowledge of both relative (?r) and incremental (pri) permeabilities. Some measurements have been made of ?ri as a function of Hdc in a ring sample and form the basis on which an analytical model of the phenomenon has been developed and some finite‐element studies have been performed.

To propose an air‐gap element for electrical machine simulation which accounts for static and dynamic rotor eccentricity.

The air‐gap element technique is extended to account for a non‐centered rotor. The consistency, stability and convergence of the discretisation error are studied. A specialized efficient solution technique combining the conjugate gradient algorithm with fast Fourier transforms is developed.

The eccentric air‐gap technique offers better discretisation properties than the classical techniques based on remeshing. Thanks to the specialized solver, the computation times remain comparable.

The introduction of eccentricity in the air‐gap element used for finite element electrical machine simulation is a new development.

The purpose of this study is to find out the influence degree of harmonic current on the generator operating parameters. In practical operation of the salient-pole synchronous generator, the heat generated by eddy current loss may lead to the breaking of damper winding, and the damper winding is a key component for ensuring the reliable operation of generators. Therefore, it is important to study the distribution characteristics and the influence factors of eddy current loss. Taking a 24-MW bulb tubular turbine generator as a reference, the influence factors that affect the eddy current loss of damper winding are analyzed.

A two-dimensional (2-D) electromagnetic field model of the generator is established, and the correctness of the model is verified by comparing simulation results and experiment data. The eddy current losses of damper winding in various conditions are calculated by using the finite element method.

It is identified that the cogging effect, pole shoe magnetic saturation degree, pole arc coefficient and armature reaction are the main factors that affect the eddy current loss of the generator rotor. When the generator is installed with magnetic slot wedges, the distribution characteristic of eddy current loss is obtained through the study of the eddy current density distributions in the damper bars. The variations of eddy current losses with time are gained when the generator has different permeability slot wedges, pole arc coefficients and pole shoe magnetic saturation degrees.

The study of this paper provides a theoretical reference for the design and optimization of bulb tubular turbine generator structure.

The research can help enhance the understanding of eddy current distribution characteristics and influence factors of eddy current loss in bulb tubular turbine generator.

The purpose of this paper is to present the influence of inter-turn short circuit faults (ITSF) on electromagnetic vibration in high-voltage line-starting permanent magnet synchronous motor (HVLSPMSMS).

In this paper, the ampere–conductor wave model of HVLSPMSM after ITSF is established. Second, a mathematical model of the magnetic field after ITSF is established, and the influence law of the ITSF on the air-gap magnetic field is analyzed. Further, the mathematical expression of the electromagnetic force density is established based on the Maxwell tensor method. The impact of HVLSPMSM torque ripple frequency, radial electromagnetic force spatial–temporal distribution and rotor unbalanced magnetic tension force by ITSF is revealed. Finally, the electromagnetic–mechanical coupling model of HVLSPMSM is established, and the vibration spectra of the motor with different degrees of ITSF are solved by numerical calculation.

In this study, it is found that the 2np order flux density harmonics and (2 N + 1) p order electromagnetic forces are not generated when ITSF occurs in HVLSPMSM.

By analyzing the multi-harmonics of HVLSPMSM after ITSF, this paper provides a reliable method for troubleshooting from the perspective of vibration and torque fluctuation and rotor unbalanced electromagnetic force.

Accurate prediction of temperature distribution in an electrical machine at the design stage is becoming increasingly important. It is essential to know the locations and magnitudes of hot spot temperatures for optimum design of electrical machines. A methodology based on axi‐symmetric finite element formulation has been developed to solve the conduction‐convection problem in radial cooled machines using a new eight noded solid‐fluid coupled element. The axi‐symmetric model adopted is formulated purely from dimensional data, property data and published convective correlations. Steady state temperatures have been determined for 102 kW radial cooled motor at 100 percent and 75 percent loads and are validated with experimental results obtained from heat run tests. Parametric studies have been carried out to study the effect of critical parameters on temperature distribution and for optimising the design.

Operation of synchronous machines in the power range of several 10 MW with variable speed up to 7,000 rpm using a current converter is, thanks to the development of power switches, possible and economically reasonable today. However, current harmonics, produced by converter, generate additional losses, especially eddy current losses on the rotor surface are produced by the converter, which strongly depend on the rotor permeability. The purpose of this paper is to show that an accurate machine modeling is required, in order to consider the nonlinearity of electromagnetic processes inside.

This paper concentrates on the determination of the rotor surface losses in a three‐phase turbogenerator feeding a current converter. Saturation of rotor steel is taken into account using a transient finite element method model of the machine, coupled with a converter model.

A detailed analysis of the damper currents and losses in a turbogenerator operating with a frequency converter is presented. The effectivenes of damper winding modifications, concerning the eddy current loss reduction in the rotor surface, is depicted.

The introduced modelling technique presents an accurate electromagnetic modelling of an I‐converter‐fed synchronous generator with massiv poles, which is fed by a current converter and so has to sustain additional eddy current losses in the rotor surface. In this way, the amount and distribution of these losses are evaluated more accurately which allows a more efficient design of the damper winding as well as machine cooling system.

Some researchers have made contributions to the analysis of current converter‐fed synchronous machine, regarding terminal behaviour of the machine. This paper focuses on eddy current losses on the rotor surface, considering the time and space dependent saturation aspect in the machine, particularly in the rotor.