Study on Simulation and Test of Temperature Rise Characteristics of 35 kV Oil-immersed Three-phase Transformer Considering Cumulative Effect
Transformers are in long-term non-stop operation,and the temperature rise caused by heat sources such as Joule heating and electromagnetic heating seriously affect the operation state and life of the transformer.To obtain the hot spot temperature and temperature rise characteristics of 35 kV oil-immersed transformer more accurately,in view of the time scale change characteristics of parameters under the influence of temperature that have not been considered in existing research,this paper considers the impact brought by the cumulative effect of temperature and carries out research on the temperature rise characteristics of oil-immersed transformer.Firstly,the theoretical model of time-varying current density and magnetic flux density was established.Based on the multi-physics field coupling simulation method,the finite element simulation analysis of electromagnetic field,temperature field,and flow field in an oil-immersed transformer under load working process was carried out.The results and distribution characteristics of the internal temperature of the oil tank under the action of core,winding,and leakage magnetic loss were obtained.Finally,long-term load operation experiments of the transformer were carried out to collect the temperatures of primary and secondary winding under the riser.The simulations find the temperature near the winding is about 95 ℃,and there are also high-temperature areas in the right angle area of the core and under the riser.The reason is that the oil flow rate at this position is large,and can reach 28 mm/s.The comparison results between experiment and simulation show that the simulation results considering cumulative effect are close to the measured values.This study can provide technical reference for temperature rise characteristics of oil-immersed transformers.
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维普
