Determination of temperature distribution on windings of oil transformer based on the laws of heat transfer

Abstract

Object of research: development of a technology for determining the temperature of the winding of a power oil transformer, in particular, the analysis of thermal processes in the winding of a power transformer during short-term overloads, taking into account the influence of the environment.
 Investigated problem: temperature distribution in the winding of a power oil transformer taking into account short-term load surges in the problem of assessing the residual life of the insulation of the transformer winding by temperature aging. The calculation of the temperature distribution in the winding was carried out using the passport data and characteristics of the power oil transformer, including the winding, transformer oil, load currents.
 Main scientific results: a mathematical model was calculated, with the help of which the results of temperature distribution in the transformer winding were obtained during short-term load surges or constant work with an increased load. According to the presented model, the analysis of the cooling time of the transformer winding after short-term overloads is carried out. Comparing the results obtained on the simulation model with the known results of experimental studies of the temperature distribution in the winding of a power transformer, the adequacy of the mathematical model is proved. It is shown that the use of the laws of heat transfer in a homogeneous plate to analyze the temperature distribution in the transformer winding is not wrong, but requires clarifications and simplifications.
 The area of practical use of the research results: enterprises of the machine-building industry and energy companies specializing in the production and operation of transformer equipment. Innovative technological product: simulation model of heat distribution in a transformer winding, which can take into account the load of the transformer, the effect of the environment on the insulation of the transformer windings.
 An innovative technological product: a method for diagnosing the duration of the non-failure operation of a transformer, which makes it possible to ensure trouble-free operation and save money for the repair of transformer equipment.
 Scope of application of the innovative technological product: design and development of diagnostic systems for windings of power oil transformers

Mathematical Model of Empirical Distribution Law of Power Transformer Failure Due to Winding Damage

“…Тому наявність частих поломок, а як наслідоквідключення споживачів, є справою звичною. Питання діагностування силових трансформаторів висвітлено в роботах [5]- [8]. Однак цікавим є й питання прогнозування виходу з ладу силових трансформаторів з метою забезпечення необхідної кількості запасних частин для їхнього швидкого відновлення.…”

“…Гіпотезу про нормальний логарифмічний закон розподілу виходу з ладу трансформаторів через пошкодження обмоток перевірятимемо з використанням χ 2 -критерію Пірсона, для якого необхідним є визначення статистики Q 2 [8] ( )…”

Method for assessing unevenness of cellulose insulation layers aging of power transformers winding

“…Known thermodynamic models are built on the basis of various differential equations of the heat balance of the transformer, which use various transformer equivalent circuits [11,12]. Solutions of these equations are found both by analytical methods [13] and by computer simulation [11,[14][15][16].…”

“…Then condition (15) can be rewritten in the form: 1  F (18) Moreover, the greatest underestimation of the aging intensity is achieved with a minimum index F. Substituting expressions (11)(12)(13)(14) into expression (17), we obtain an expression for determining F: 19), taking into account (8), ( 9) and approximation results in Fig. 4, we obtain: Analysis of expressions ( 15) and (16) shows that:…”