Transformer hot-spot temperature estimation for short-time dynamic loading

Josue, Fretz; Arifianto, Indera; Saers, Robert; Rosenlind, Johanna; Hilber, Patrik; Suwarno, &

doi:10.1109/cmd.2012.6416414

Cited by 14 publications

(6 citation statements)

References 4 publications

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“…Josue [44] (2012) Like Susa, this model modifies the IEC 60076-7 loading guides by investigating the variation of transformer oil viscosity with temperature, along with the dependence of winding losses on temperature. The oil temperature is equated to the HST to determine the change in its viscosity and simulate the extreme condition.…”

Section: )mentioning

confidence: 99%

Thermoelectric Modelling and Optimization of Offshore Windfarm Export Systems - State of the Art

Kazmi

Holbøll

Olesen

et al. 2019

2019 1st Global Power, Energy and Communication Conference (GPECOM)

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With recent developments and cost reduction, offshore windfarms are set to lead the energy markets of the west by 2030. This development can further be accelerated if the wind intensive periods can be utilized efficiently by optimizing the limited network capacity and if the energy output is increased during contingency outages. Therefore, dynamic rating operation of components that are primary system bottlenecks becomes crucial. This paper identifies potential bottlenecks in offshore windfarm export systems and provides an extensive state-of-the-art review of dynamic thermoelectric models which are applicable for real-time loadability assessment of the identified components. The loadability of these components is directly dependent on their thermal state, which is evaluated based on analytical solutions of the dynamic thermoelectric model, including the complicated heat transfer and temperature development phenomena in the identified components. Moreover, potential risks of using these models for offshore windfarm applications are also identified.

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Section: )mentioning

confidence: 99%

Thermoelectric Modelling and Optimization of Offshore Windfarm Export Systems - State of the Art

Kazmi

Holbøll

Olesen

et al. 2019

2019 1st Global Power, Energy and Communication Conference (GPECOM)

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“…As a result of measurements, when a critical or significant change is observed in the properties of the oil, necessary measures can be taken. In the literature, there are many methods and studies used to diagnose dielectric performance of transformer oils, and experience in this field has been standardized [32][33][34][35][36][37][38][39][40]. However, the situation of transformer boards (TB) used for both insulation and cooling purposes is more complex than transformer oils.…”

Section: Introductionmentioning

confidence: 99%

Determination of transformer board creep parameters under high‐mechanical and thermal stresses

Arabul

Kumru

Arabul

2020

IET Science Measure & Tech

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During operation of a transformer, all components inside the transformer begin to age and lose their performances due to various stresses. Among these components, transformer boards (TB) used between windings have an important role in terms of equipment reliability for being used for both insulation and cooling purposes. TBs are exposed to all sorts of specified stresses during operation and their physical structure deteriorates by creeping over time. This deterioration leads to a decrease in the gap between winding turns, and insulation failures occur due to insufficient cooling. In order to prevent these types of failures, it is quite important to specify creep characteristics of TBs before the production particularly for high‐mechanical and thermal stresses. In this study, creep parameters (secondary creep rate, time to breakdown) of TB samples used in a typical power transformer under various loading and temperature are determined experimentally. In addition, gradient values are calculated for fitted lines and results obtained evaluated in terms of transformer operating conditions. Creep data obtained under high temperature (90, 100 and 110°C) and loading (30, 35 and 40 kg) makes an important contribution to literature and will help transformer manufacturers in design and production stages.

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“…Failure of oil insulation may cause the transformer failure leading to the interruption of power delivery. Thermal ageing can change the dielectric properties of insulation oil [7][8][9][10]. In this paper, the experimental results on the thermal aging of kraft paper-mineral oil composite insulation is presented.…”

Section: Introductionmentioning

confidence: 99%

Thermal Aging of Mineral Oil -Paper Composite Insulation for High Voltage Transformer

Suwarno¹,

Pasaribu²

2016

ijeei

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High voltage transformer is one of the most important equipments in an electric power system. High voltage insulation plays important role in determining transformer performance and greatly determines the lifetime. In general, paper and oil composite is used as main insulations in a high voltage transformer. Due to thermal aging, the insulation performances of the insulation may be degraded. The degradation mechanisms are important to be clarified. This paper reports the experimental results on the effects of thermal aging on the properties of paper-oil composite insulation. The samples used were thermally upgraded kraft paper and mineral oil. They are widely used in high voltage transformers. Samples were conditioned to the same initial conditions through the heating at a temperature of 100 °C for 24 hours. Mineral oil samples with volume of 800 ml and 6 gram insulating kraft paper were put in hermetical bottles. The paper-oil ratio reflects the typical ratio of oil and kraft paper inside a real transformer. The bottles containing oil and paper samples were subjected to thermal aging at 120 o C and 150 o C in a controllable oven for a period up to 4 weeks. Dielectric properties of the oil such as breakdown voltage, resistivity, water content were measured after and before aging. Dissolved gas analysis (DGA) was used to identify the gasses released in the paper-oil composite insulation as the results of thermal aging process. The morphological aging of the kraft paper was investigated using SEM (scanning electron microscopy) while chemical element change was investigated using EDS (energy dispersive spectroscopy) with accelerated voltage of 0.3-30 kV. The results showed that the dielectric properties will decrease with the increasing duration and temperature of aging. From these experiments obtained CO gases, produced from thermal degradation of paper cellulose chain. H 2 and C 2 H 2 gases are not generated in this experiment. The result was consistent since H 2 usually generated under partial discharges while C 2 H 2 released under very high temperature such as partial combustion, electric arc which were not available in the experiment. Some hydrocarbon gas such as CH 4 , C 2 H 4 and C 2 H 6 were detected. CO gas was obtained as the result thermal aging of paper insulation through oxidation process. The EDS analysis showed that during aging the C element increased while O element decreased. EDS data of krafft paper aged at 120 o C for a duration of 4 weeks (672 hours) taken using JEOL 6510 at accelerated voltage of 10 kV with energy range of 0-20 kV showed that the aged paper consists of 3 elements, C , O and K elements with mass percentage of 75.23 % of C at energy of 0.277 kV, O of 21.69 % observed at energy of 0.525 kV and new element of K with mass percentage of 3.08 observed at energy of 3.312 kV. It is clearly observed that C increased from 58.83 % to 75.23 %. This is due to the migration from the ester into the paper on the other hand oxygen reduced from 41.17 % to 21.69 % because the oxygen from the pape...

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Transformer hot-spot temperature estimation for short-time dynamic loading

Cited by 14 publications

References 4 publications

Thermoelectric Modelling and Optimization of Offshore Windfarm Export Systems - State of the Art

Thermoelectric Modelling and Optimization of Offshore Windfarm Export Systems - State of the Art

Determination of transformer board creep parameters under high‐mechanical and thermal stresses

Thermal Aging of Mineral Oil -Paper Composite Insulation for High Voltage Transformer

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