换流变压器不同工况下的铁心磁特性研究

Study on the Magnetic Characteristics of Core of Converter Transformer Under Different Working Conditions

换流变压器在发生绕组内部短路故障工况下,其绕组内部短路环会流过较大的短路电流,该短路环引起的空间漏磁通会对铁心饱和效应。以某工程一台实际换流变压器产品为例,借助3D有限元仿真时谐求解对变压器在非故障条件下的空载运行工况、负载运行工况的铁心磁密进行了仿真分析,发现铁心在空载与负载工况下磁密分布云图类似且均未发生饱和,仿真得到了在负载感性负载条件下由于空间漏磁的叠加主磁通会对芯柱磁通有削弱效果。对变压器在内部短路故障条件下的空载运行工况、负载运行工况的器身整体磁密进行了仿真分析,通过对比不同工况条件下铁心内部与空间的磁通分布,证明了变压器在发生内部短路故障工况下铁心会由于短路安匝而产生局部区域性的饱和,提出了在故障分析条件下绕组内部受力分析需要考核变压器由于铁心饱对漏磁边界的影响,对研究变压器故障条件下内部短路绕组受体分析具有一定的参考意义。

Under the condition of internal short-circuit fault in the winding of converter transformer,the internal short-circuit ring of the winding will flow large short-circuit current,the core will be saturated effect due to the short cirucit ring’s stray flux.Taking an actual converter transformer product of a project as an example,the magnetic density of the iron core under no-load operation condition and load operation condition of the transformer under non fault conditions was analyzed with 3D finite element simulation time harmonic method.It was found that the magnetic density distribution under the iron core under no-load and load conditions was similar and non-saturated.The simulation showed that under the load inductive load condition,due to the superposition of magnetic leakage,the main magnetic flux would weaken the magnetic flux of the core column.The magnetic density of the iron core under no-load operation condition and load operation condition of the transformer under the condition of internal short-circuit fault was simulated and analyzed.By comparing the magnetic flux distribution in the iron core and stray duct under different working conditions,it was proved that the iron core of the transformer will be locally saturated due to short-circuit ampere turn under the condition of internal short-circuit fault.It was proposed that under the condition of fault analysis,the internal force analysis of the winding needed to examine the influence of the magnetic leakage boundary of the transformer due to the saturation of the iron core,which had a certain reference significance for analysis of the internal short-circuit winding of the transformer.