考虑累积效应的35 kV油浸式三相变压器温升特性仿真与试验研究

Study on Simulation and Test of Temperature Rise Characteristics of 35 kV Oil-immersed Three-phase Transformer Considering Cumulative Effect

变压器长期处于不停机运行状态,焦耳热、电磁热等热源产生的温升会严重影响变压器的运行状态和使用寿命。为了更准确地得到35 kV油浸式变压器的热点温度和温升特性,针对现有研究未考虑温度影响下参数的时间尺度变化特征的问题,考虑温度累积效应带来的影响,围绕油浸式变压器的温升特性展开研究。首先,建立时变电流密度、磁感应强度的理论模型;其次,基于电磁热流多物理场耦合仿真方法,对油浸式变压器带负载工作过程进行电磁场、温度场及流场的有限元仿真分析,得到了铁心、绕组及漏磁损耗作用下油箱内部温度变化及其分布特性;最后,完成油浸式变压器长期带负载运行实验,并采集得到升高座下方及初级、次级绕组温度。仿真发现绕组附近温度约为95℃,铁心的直角区域及升高座下方也存在高温区,原因是该位置油流流速较大,仿真结果约为28 mm/s。实验与仿真的对照结果表明,考虑累积效应的仿真结果与实测值较为接近。研究内容可为油浸式变压器的温升特性提供技术参考。

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.