Hundred years of experience in the dynamic thermal modelling of power transformers

Modelagem matemática do comportamento térmico de subestações subterrâneas considerando dados reais

“…Um dos primeiros trabalhos que propôs um modelo matemático para prever o comportamento térmico de subestações de distribuição subterrânea, sob vários tipos de carga, foi desenvolvido por Whirlow and Lockie (1968). Este modelo é um modelo clássico bastante referenciado em estudos de redes de distribuição subterrâneas quando o tema envolve análise térmica, e a partir dele diversos outros trabalhos surgiram na literatura (Djamali and Tenbohlen, 2017, Djamali et al, 2018, Sandraz et al, 2013. O modelo de Whirlow and Lockie (1968) considera que os componentes, tanto internos quanto externos possuem uma capacitância térmica e uma resistência térmica em relação ao fluxo de calor, de componente para componente.…”

Analysis of thermal models to determine the loss of life of mineral oil immersed transformers

“…Oil and paper in transformers are two insulation materials, that the integrity of them warranties the life of transformers. Hot spot temperature (HST) and top oil temperature (TOT) are two criteria to evaluate the integrity of these two insulation materials and transformers as important facility in power network [1]- [3]. These criteria determine the temperature limitation of transformer for loading capability, for example the IEEE standard suggests that the TOT rise over ambient temperature 65°C and depending on it has considered 110°C for HST [4]- [6].…”

Thermal analysis and derating of a power transformer with harmonic loads

“…In addition, different experimental results for the estimation of non-linear resistances coefficients and equivalent thermal capacitances were used. However, different components of transformer have not been separately modelled as such that windings losses and no-load losses are included as heat-generating sources and merely the winding hot-spot and top-oil temperatures are determined [14][15][16]. These TECs cannot appropriately be applied for thermal analysis of transformer with harmonic loads.…”