Bearing Load Measurement in a Hydropower Unit Using Strain Gauges Installed Inside Pivot Pin

Nässelqvist, Mattias; Gustavsson, Rolf; Aidanpää, Jan-Olov

doi:10.1007/s11340-011-9495-y

Cited by 14 publications

(9 citation statements)

References 9 publications

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“…Based on previous tests, Nässelqvist et al [15] considered that the radial static load in the journal bearings of a 42 MW hydrogenerator of vertical assembly was 30 kN. In other references, the radial static load was measured using strain gauges installed in the bearing bracket arms [16] or in the pivot pins of the bearing pads [17]. This load may be also estimated using curves relating radial load with shaft eccentricity, calculated previously.…”

Section: Remarks On Lhg Modelsmentioning

confidence: 99%

“…Even in the more refined models, once the shaft eccentricity is determined, the pads clearances are calculated considering that the pivot point of all pads lies in a perfect circle. This means that the bearing housing is ideal, without the dimensional changes described in the previous section (Nässelqvist et al [17] comment that the geometry of hydrogenerator bearing brackets "changes with temperature, as the generator temperature varies from between 15 and 80 ∘ C," influencing "bearing clearances, which changes the relation between bearing properties"; however, apparently, no further investigations were done in this direction). Then bearing coefficients are determined, considering only the oil film hydrodynamic effects (hydrodynamic model) or considering the additional thermal effects from bearing losses (thermohydrodynamic or THD model) or with the deformation effects created by the oil film pressure (thermoelastohydrodynamic or TEHD model) [21].…”

Section: Remarks On Lhg Modelsmentioning

confidence: 99%

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Using Simplified Models to Assist Fault Detection and Diagnosis in Large Hydrogenerators

Brito

Machado

Neto

2017

International Journal of Rotating Machinery

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Based on experimental evidence collected in a set of twenty 700 MW hydrogenerators, this article shows that the operating conditions of large hydrogenerators journal bearings may have unpredictable and significant changes, without apparent reasons. These changes prevent the accurate determination of bearing dynamic coefficients and make the prediction of these machines dynamic behavior unfeasible, even using refined models. This makes it difficult to differentiate the normal changes in hydrogenerators dynamics from the changes created by a fault event. To overcome such difficulty, this article proposes a back-to-basics step, the using of simplified mathematical models to assist hydrogenerators vibration monitoring and exemplifies this proposal by modeling a 700 MW hydrogenerator. A first model estimates the influence of changes in bearing operating conditions in the bearing stiffnesses, considering only the hydrodynamic effects of an isoviscous oil film with linear thickness distribution. A second model simulates hydrogenerators dynamics using only 10 degrees of freedom, giving the monitored vibrations as outputs, under normal operating conditions or in the presence of a fault. This article shows that simplified models may give satisfactory results when bearing operating conditions are properly determined, results comparable to those obtained by more refined models or by measurements in the modeled hydrogenerator.

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Section: Remarks On Lhg Modelsmentioning

confidence: 99%

Section: Remarks On Lhg Modelsmentioning

confidence: 99%

Using Simplified Models to Assist Fault Detection and Diagnosis in Large Hydrogenerators

Brito

Machado

Neto

2017

International Journal of Rotating Machinery

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“…Giving sequence to the previous work, Nässelqvist et al [16] also in this methodology. Equation (1) is expressed in frequency domain, at a certain frequency Ω, as…”

Section: Introductionmentioning

confidence: 99%

Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators

Brito

Machado

Neto

2017

Shock and Vibration

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Based on experimental pieces of evidence collected in a set of twenty healthy large hydrogenerators, this article shows that the operating conditions of the tilting pad journal bearings of these machines may have unpredictable and significant changes. This behavior prevents the theoretical determination of bearing stiffness and damping coefficients with an adequate accuracy and makes damage detection difficult. Considering that dynamic coefficients have similar sensitivity to damage and considering that it is easier to monitor bearing stiffness than bearing damping, this article discusses a method to estimate experimentally the effective stiffness coefficients of hydrogenerators journal bearings, using only the usually monitored vibrations, with damage detection purposes. Validated using vibration signals synthesized by a simplified mathematical model that simulates the dynamic behavior of large hydrogenerators, the method was applied to a journal bearing of a 700 MW hydrogenerator, using two different excitations, the generator rotor unbalance and the vortices formed in the turbine rotor when this machine operates at partial loads. The experimental bearing stiffnesses obtained using both excitations were similar, but they were also much lower than the theoretical predictions. The article briefly discusses the causes of these discrepancies, the method's uncertainties, and the possible improvements in its application.

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“…These methods are more active in the field of research, but have little application in engineering. The classical identification methods are still mainly used in engineering application [12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Hydropower unit model identification using the field data

Wei¹,

Guo²,

Wu³

et al. 2017

Proceedings of the 2016 International Forum on Mechanical, Control and Automation (IFMCA 2016)

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Abstract:A model identification method of hydropower unit (HU) based on Auto-Regressive and Moving Average (ARMA) has been proposed. The ARMA model coefficients were obtained by least square method. Using the proposed method, the parameters e y , e, and e qh of hydro turbine can be calculated. Experiment results show that the model identification simulations were consistent with the measured data of field tests.

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Bearing Load Measurement in a Hydropower Unit Using Strain Gauges Installed Inside Pivot Pin

Cited by 14 publications

References 9 publications

Using Simplified Models to Assist Fault Detection and Diagnosis in Large Hydrogenerators

Using Simplified Models to Assist Fault Detection and Diagnosis in Large Hydrogenerators

Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators

Hydropower unit model identification using the field data

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