An improved computational approach for thermal modeling of power transformers

Abstract

SUMMARYProposed IEEE/ANSI differential equation governing top oil temperature rise, and its improvements are widely used in top oil temperature prediction and parameter estimation for power transformer loss of life calculation and diagnostic systems. Approximately, all transformer thermal models employ backward Euler method to achieve related set of equations (or regressors) and use least square error estimator for parameter estimation. In this paper, we applied a new numerical integration methodology to solve the differential equation of thermal model. Related matrix format is calculated based on the numerical integration rectangle rule. Some comparison metrics are introduced to verify and compare the proposed computation methodology with conventional discretized backward Euler equation. The proposed method was tested on simulated top oil temperature using measured ambient temperature and load data in the field. Results showed a significant and meaningful improvement in top oil temperature prediction. Variations of calculated parameters, in the presence of noise, presented the superiority and advantages of the proposed computational methodology.

Fast computation of hot spots temperature due to high current cable leads in power transformers tank walls

“…To simulate convection between transformer oil and tank wall (inside the transformer) a top oil temperature T top _ oil = 72.3 °C and a convective heat transfer coefficient h oil‐tank = 138 W / m 2 K are determined and set to the internal face of tank wall using the theory showed from .…”

Reliability evaluation of distribution transformers considering the negative and positive effects of rooftop photovoltaics

“…Time and temperature are the main parameters for the transformer's insulation deterioration [13][14][15]. The HST of the transformer winding should be considered for the transformer thermal ageing failure evaluation [16].…”

“…Equation 3calculates the top oil temperature of the ith transformer rise over the ambient temperature in the steady state. After the calculation of θ ultO i , the transient top oil temperature rise over ambient temperature can be computed in (4) [13][14][15][16] P LP = P conv − P RPV if P conv ≥ P RPV direct P RPV − P conv if P conv < P RPV reverse (1)…”

Numerical and Experimental Evaluation and Heat Transfer Characteristics of a Soft Magnetic Transformer Built from Laminated Steel Plates

“…They provide a useful yet simple tool to evaluate the temperature evolution in the transformer, which can suffer dramatic heating due to its losses that can severely impact its overall efficiency. The thermal evaluation of a transformer is usually done using analytical thermal-circuit models or more complex simulations involving Finite Element Method (FEM) and/or Computational Fluid Dynamics (CFD) [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Numerous articles are present in the literature devoted to analytical methods to predict the temperature distribution in transformers [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”