Comprehensive electrical and thermal analysis of the stress grading system of a large hydro generator

Staubach, Christian; Hildinger, Thomas; Staubach, Axel

doi:10.1109/mei.2018.8246120

Cited by 19 publications

(11 citation statements)

References 3 publications

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“…In order to verify the correctness of the model presented in this paper, the result of Ref. [28] is used as a reference. The stator bar of a hydro generator at the end region with a rated voltage of 20 kV is analyzed using the finite element method in Ref.…”

Section: Influence Of Nonlinear Corona Protection Materials On the Dismentioning

confidence: 99%

“…The stator bar of a hydro generator at the end region with a rated voltage of 20 kV is analyzed using the finite element method in Ref. [28]. The distribution of the electric field strength is shown in Figure 7, which only shows the color plot of the ECP, and the maximum field strength is 3.77 kV/cm in the ECP/OCP overlapping area.…”

Section: Influence Of Nonlinear Corona Protection Materials On the Dismentioning

confidence: 99%

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Optimization of the Electric Field Distribution at the End of the Stator in a Large Generator

Zhang

et al. 2018

Energies

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The electric field distribution at the end of a large hydro-generator is highly nonuniform and prone to corona discharge, which damages the main insulation and significantly reduces the service life of the hydro-generator. In order to reduce the thickness of the main insulation and the physical size of a large hydro-generator, it is necessary to understand the distribution of the electric field at the end of its stator bar. In this paper, the stator bar at the end of a large generator is simulated using the finite element method to determine the distribution of the potential, electric field, and loss at the rated voltage, as well as to elucidate the differences between the linear corona protection, two-segment nonlinear corona protection, and three-segment nonlinear corona protection structures. The influences of the arc angle, length of each corona protection layer, intrinsic resistivity of the corona protection material, and nonlinear coefficient are also analyzed. The results manifest that the angle of the stator bar should be 22.5 • , the difference in resistivity between the two adjacent corona protection coatings should not exceed two orders of magnitude, and the resistivity of the medium resistivity layer should be nearly 10 6 Ω·m or 10 7 Ω·m, for an optimal design of the corona protection structure.

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Section: Influence Of Nonlinear Corona Protection Materials On the Dismentioning

confidence: 99%

Section: Influence Of Nonlinear Corona Protection Materials On the Dismentioning

confidence: 99%

Optimization of the Electric Field Distribution at the End of the Stator in a Large Generator

Zhang

et al. 2018

Energies

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“…FEM has become one of the most commonly used techniques for modeling stress-grading systems [37][38][39]. With FEM, the geometry can be considered including most of the details that influence the electric field distribution.…”

Section: Modeling Of Stress-grading Systems From Rotating Machinesmentioning

confidence: 99%

Modeling and Simulation of Rotating Machine Windings Fed by High-Power Frequency Converters for Insulation Design

Cortés¹,

Gómez²,

KhalilHussain³

2018

Simulation and Modelling of Electrical Insulation Weaknesses in Electrical Equipment

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Modern power systems include a considerable amount of power electronic converters related to the introduction of renewable energy sources, high-voltage direct current (HVDC) systems, adjustable speed drives, and so on. These components introduce repetitive pulses generated by the commutation of semiconductor switches, resulting in overvoltages with very steep fronts and high dielectric stresses. This phenomenon is one of the main causes of accelerated insulation aging of motors in power electronic-based systems. This chapter presents state-of-the-art computational tools for the analysis of motor windings excited by fast-front pulses related to the use of frequency converters based on pulsewidth modulation (PWM). These tools can be applied for the accurate prediction of overvoltages and dielectric stresses required to propose insulation design improvements. In the case of the stress-grading system used in medium-voltage (MV) motors, transient finite-element method (FEM) is used to study the effect of fast pulses. It is shown how, by controlling the material properties and the design of the stress-grading systems, solutions to reduce the adverse effects of fast pulses from PWM-type inverters can be proposed.

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“…of generator vibration to find out e.g. the vibrations effects on the stator winding and insulation [17], [18], [19]. The end winding vibration is also an important aspect which is considered in the previous works [5].…”

Section: Introductionmentioning

confidence: 99%

“…The converter is connected to the common 1000 V DC bus (15). The AC-DC conversion is realized with the line converter (18) which is connected via a power switch bank (19) to the electrical grid. The DFIG can Fig.…”

Section: Introductionmentioning

confidence: 99%

Characterization of a Large Electrical Machine Test

Ebrahimi¹

2018

Preprint

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The acceptability and also the acceleration ofrenewable energy technologies is tightly linked with a betterunderstanding of dynamic behavior of drive train componentsand their interactions. This ultimate understanding of systemcharacteristics can only be achieved with comprehensiveexperimental investigations on different phenomena of largeelectrical generators. This leads consequently to a betterverification of numerical and analytical models of largegenerators. The large generator-converter lab which is discussedin this paper is a unique opportunity for deep experimentalinvestigations on large hydro and wind generators. It is designedto deal with the current as well as future research topics in thefield of wind and hydro generators and their interactions withpower electronic devices and electrical grid.

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Comprehensive electrical and thermal analysis of the stress grading system of a large hydro generator

Cited by 19 publications

References 3 publications

Optimization of the Electric Field Distribution at the End of the Stator in a Large Generator

Optimization of the Electric Field Distribution at the End of the Stator in a Large Generator

Modeling and Simulation of Rotating Machine Windings Fed by High-Power Frequency Converters for Insulation Design

Characterization of a Large Electrical Machine Test

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