Use of Alternative Fluids in Very High-Power Transformers: Experimental and Numerical Thermal Studies

Altay, Ramazan; Santisteban, A.; Olmo, Cristian; Estébanez, Carlos Javier Renedo; Fernández, Federico; Delgado, F.

doi:10.1109/access.2020.3037672

Cited by 13 publications

(6 citation statements)

References 24 publications

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“…Numerical simulations carried out have shown that the temperatures reached in a transformer using esters could be similar, or even lower, to those reached with mineral oils in adapted winding designs [12], [13], [14] Some manufacturers apply special treatments to improve the viscosity or the oxidation stability of these alternative liquids [15]. The effect of the fluid used on the degradation of the solid insulation, measured by the control of the chemical [16], mechanical [17] or light techniques [18] after a thermal [19] or electrical [20] ageing process, have also been afforded.…”

Section: Introductionmentioning

confidence: 94%

Understanding the Ageing Performance of Alternative Dielectric Fluids

et al. 2023

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Mineral oil has traditionally been used as a cooling fluid in power transformers, but its low biodegradability and low fire point have motivated the search of alternatives. In this work, six different dielectric fluids have been studied, including four vegetable liquids, from sunflower, rapeseed, soybean, and palm, one synthetic ester and a mineral oil used for comparison. These oils were subjected to an accelerated thermal ageing in glass vessels at 150 • C for four weeks (672 hours) in presence of Kraft insulating paper. Different oils parameters were measured during the ageing, i.e. breakdown voltage, dielectric dissipation factor, permittivity, DC resistivity, density, kinematic viscosity, flash and fire points, interfacial tension, acidity, and dissolved gases; additionally, the degree of polymerisation (DP) of the paper was measured. Results showed that the changes of the natural esters properties, except for the palm oil, were similar along the ageing time. Palm oil results were similar to those of the mineral oil, whereas synthetic ester showed a behaviour similar to natural esters. The kraft paper degradation was higher in the mineral oil, followed by the synthetic ester and the palm oil. No significant differences were found in the ageing with the natural esters.INDEX TERMS Insulating paper, natural esters, thermal ageing, transformers.

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Section: Introductionmentioning

confidence: 94%

Understanding the Ageing Performance of Alternative Dielectric Fluids

et al. 2023

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“…The output parameters in the data set are v-funnel (VF), T50, slump-flow (SF) and compressive strength (Fc). Silica fume, silica powder and stone fume are reduce the workability of the fresh concrete takes as group (Altay, Ulas & Alyamac, 2020). The effect of this group on the performance of concrete that has been hardened before 28 days is negligible.…”

Section: And Hidden Nodesñ;mentioning

confidence: 99%

DCS-ELM: a novel method for extreme learning machine for regression problems and a new approach for the SFRSCC

Altay¹,

Ulaş²,

Alyamaç³

2021

PeerJ Computer Science

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Extreme learning machine (ELM) algorithm is widely used in regression and classification problems due to its advantages such as speed and high-performance rate. Different artificial intelligence-based optimization methods and chaotic systems have been proposed for the development of the ELM. However, a generalized solution method and success rate at the desired level could not be obtained. In this study, a new method is proposed as a result of developing the ELM algorithm used in regression problems with discrete-time chaotic systems. ELM algorithm has been improved by testing five different chaotic maps (Chebyshev, iterative, logistic, piecewise, tent) from chaotic systems. The proposed discrete-time chaotic systems based ELM (DCS-ELM) algorithm has been tested in steel fiber reinforced self-compacting concrete data sets and public four different datasets, and a result of its performance compared with the basic ELM algorithm, linear regression, support vector regression, kernel ELM algorithm and weighted ELM algorithm. It has been observed that it gives a better performance than other algorithms.

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“…The model uses a structured hexahedral mesh of 14 M elements for the CFD analysis. Mesh independence test and validation of the CFD model have been carried out a previous work of the authors [7].…”

Section: ∇ (4)mentioning

confidence: 99%

“…With the results of these works, the temperatures in the different parts of the transformer windings can be known. This information is vital to using the proper type of solid insulation [7,8].…”

Section: Introductionmentioning

confidence: 99%

Effect of the Thermal Characteristics of Dielectric Fluids on the Loading Capacity of a Power Transformer

Matia¹,

Santisteban

Fernández

et al. 2022

2022 IEEE 21st International Conference on Dielectric Liquids (ICDL)

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The use of biodegradable dielectric liquids in power transformers has several advantages, such as increased fire safety or their biodegradability in the event of a leak in the tank. However, they also have a higher viscosity that does not benefit their cooling function within these machines. Although there are many references that analyze the transformers hotspot temperature for dynamic loading, there are hardly any references that focus on the dynamic evaluation of the hot-spot when the viscosity of the dielectric and cooling fluid changes, with respect to that of the oil of mineral origin. In this work, the algorithms proposed in the bibliography will be combined with the use of computational fluid dynamics software ANSYS-FLUENT, which uses the finite volumes method to solve the equations that govern fluid flow. The software tool will be used to calculate the temperatures of a 100MVA transformer winding. Once these temperatures have been calculated, they can be entered into the hot-spot temperature estimation algorithm when the machine's load regime is varied. This analysis will be repeated using dielectric liquids with different thermal characteristics. Transformer fleet managers may use the results of this study in order to adapt their procedures when the machines they manage do not have conventional mineral oil inside.

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Use of Alternative Fluids in Very High-Power Transformers: Experimental and Numerical Thermal Studies

Cited by 13 publications

References 24 publications

Understanding the Ageing Performance of Alternative Dielectric Fluids

Understanding the Ageing Performance of Alternative Dielectric Fluids

DCS-ELM: a novel method for extreme learning machine for regression problems and a new approach for the SFRSCC

Effect of the Thermal Characteristics of Dielectric Fluids on the Loading Capacity of a Power Transformer

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