Practical Modal Analysis of a Prototyped Hydrogenerator

Barros, Allan de; Galai, Ahmed; Ebrahimi, Amir; Schwarz, Babette

doi:10.3390/vibration4040048

Cited by 10 publications

(3 citation statements)

References 15 publications

(25 reference statements)

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“…Although there is a list of analytical eigenfrequency models in the literature [13]- [15], they are based on cylindrical shape assumption. They are validated mostly with smaller machines, and the interaction between the stator and core frame is more complex in large electrical machines [16], [17].…”

Section: Slot Number-loading Selectionmentioning

confidence: 99%

Winding Type Alternation of a Refurbished Old Generator

Tosun¹,

Gülletutan²,

Yakut³

et al. 2023

Preprint

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<p>Refurbishment of hydro-generators promises an increased lifespan and improved efficiency. Old generators are not only less efficient but also less reliable; their fault occurrence is more common. The economic impact of out-service time can be astronomical. Thus, refurbishment is a critical task; but it is challenging too. Most of the conducted works focus on the material update, enhancing the cooling network, and obtaining better efficiencies. Modifying winding type, i.e. conversion from lap winding to wave winding is rare since it often requires a change in the slot number. Such a move can be laborious, size change can become mandatory. In this study, a refurbishment design strategy is proposed which includes a winding type conversion. The task is to implement a wave winding since it has less out-service time and is easily replaced by field workers. In this paper, an old generator that started operation in 1956 is used for a refurbishment. This study promises a guideline to hydro-generator designers who work on a refurbishment study on old hydro-generators that have diamond coils.</p>

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Section: Slot Number-loading Selectionmentioning

confidence: 99%

Winding Type Alternation of a Refurbished Old Generator

Tosun¹,

Gülletutan²,

Yakut³

et al. 2023

Preprint

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“…Another knowledge field that plays a fundamental role in analysis of physics phenomena, and by consequence reducing costs of experimentation procedures and improving operation safety, is the realm of numerical modelling of hydrogenerators. Both two-and three-dimensional models have been developed in various areas of study [1,[17][18][19][20][21][22]. Those models employ the finite element method and encompass electromagnetic analysis [17,19], thermal analysis [18,20,21], and mechanical analysis [22].…”

Section: Introductionmentioning

confidence: 99%

“…Both two-and three-dimensional models have been developed in various areas of study [1,[17][18][19][20][21][22]. Those models employ the finite element method and encompass electromagnetic analysis [17,19], thermal analysis [18,20,21], and mechanical analysis [22]. In [18], a two-dimensional computational fluid dynamics (CFDs) model is incorporated into their thermal model.…”

Section: Introductionmentioning

confidence: 99%

Ozone Transport in 311 MVA Hydrogenerator: Computational Fluid Dynamics Modelling of Three-Dimensional Electric Machine

de Oliveira,

Girotto,

de Alcantara

et al. 2023

Energies

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In this paper, a three-dimensional turbulent fluid dynamics numerical model of a 311 MVA full hydroelectric power plant unit is made, using the finite element method, to study and understand the ozone transport mechanisms inside the enclosured electric machine structure. In the real world, ozone is produced by partial discharges related to faults on stator bars. In order to analyse ozone transport from localised sources, a 3D fluid dynamic model of a complete hydrogenerator in operation is developed and presented for the first time. The model has a high level of geometric detail. Furthermore, a new proposal to simplify the modelling of radiators is implemented and validated. The modelled structure is based on a Campos Novos hydrogenerator electric machine and it consists of 378 coil-type stator bars made of copper covered by mica and, more externally, by a semiconductor coating layer. Other parts are also represented, including the stator core and air directors made of stainless steel, copper radiators, the rotor with its epoxy surface, and the concrete floor and concrete external walls. In the fluid dynamics model, a finite element mesh was designed to represent the air regions inside the hydrogenerator and the material surfaces that react with ozone (with their respective reaction rates), where the airflow and ozone transport are modelled using the Navier–Stokes equations and the mass conservation law. Partial discharge sources are represented by ozone sources with prismatic shapes, placed on surfaces of stator bars. Ozone concentrations have been calculated inside and around the generator machine. The rotor radius is 3.8075 m and its rotation frequency is 200 RPM. Radial air velocity due to interpole ventilation is also considered (2.2 m/s, as experimentally verified in loco. The radial velocity in the vicinity of the radiators is 3 m/s. It has been concluded that the ozone transport profile is influenced by the source positioning on the stator bars in such a way that source pinpointing is possible and it depends on determining the local and global maxima areas of ozone concentration at the radiators.

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The analytical beam element model: novel approach for fast calculation of vibrations in electric machines

Gerlach

Barros

Huang

et al. 2023

Elektrotech. Inftech.

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The vibration and acoustic behavior of electric machines is an important aspect of the design process. A crucial part of the modeling is the correct prediction of the stator’s vibration behavior, characterized by the stator’s eigenfrequencies and eigenmodes. For this purpose, a calculation approach called the analytical beam element model (ABM) was presented in a previous paper [18], where Euler–Bernoulli beams were used to describe the vibration behavior of the stator. The ABM introduced offers an alternative to the finite element (FE) method and to classical analytical models. In this paper, the model is examined and extended further. Different approaches conceived to better describe the influence of the stator yoke’s thickness by using Timoshenko beams and a multi-layer discretization are presented and discussed. Furthermore, a new feature that considers the lever arm effect of the stator teeth with respect to the yoke is introduced. The results are compared to FE calculations and measurements. Lastly, the improved ABM is used to calculate the vibration behavior of four stators with outer diameters ranging from $$160\,\text{mm}$$ 160 mm to $$7\,\text{m}$$ 7 m . The results are compared to FE results to prove the accuracy of the ABM.

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Practical Modal Analysis of a Prototyped Hydrogenerator

Cited by 10 publications

References 15 publications

Winding Type Alternation of a Refurbished Old Generator

Winding Type Alternation of a Refurbished Old Generator

Ozone Transport in 311 MVA Hydrogenerator: Computational Fluid Dynamics Modelling of Three-Dimensional Electric Machine

The analytical beam element model: novel approach for fast calculation of vibrations in electric machines

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