基于场-路耦合有限元法的干式变压器匝间短路暂态特性研究

Research on Transient Characteristics of Interturn Short Circuit of Dry-Type Transformer Based on Field-Circuit Coupled Finite Element Method

因抗短路能力不足,干式变压器运行中因负荷侧出口短路引起的绕组匝间短路故障仍有发生。为提高实时监测故障的灵敏度,有必要对干式变压器绕组发生匝间短路故障时的暂态特性进行研究。首先分析了“场-路”耦合的原理;其次,利用有限元软件ANSYS建立了与干式变压器实物结构一致的二维“场-路”耦合仿真模型,并验证了该模型额定运行工况下的准确性。随后,通过耦合模型的外电路设置绕组不同位置发生匝间短路故障,分析干式变压器绕组发生单匝匝间短路故障时电磁参数的分布特征。最后,研究得到工程上易检测且变化显著的损耗因数、有功功率损耗变化率作为敏感特征状态量,所得结论可为实现干式变压器发生匝间短路故障的实时在线监测及实施提高绕组抗短路能力的措施提供针对性的理论依据。

Due to the insufficient anti-short-circuit ability of dry-type transformer,the interturn short-circuit fault of the dry-type transformer windings caused by the load side outlet short circuit in operation still occurs.In order to improve the sensitivity of realtime monitoring faults,it is urgent to study the transient characteristics of the dry-type transformer windings when the interturn short circuit fault occurs.The principle of"field-circuit"coupling is analyzed in this paper.Secondly,a two-dimensional"field-circuit"coupling simulation model is established with finite element software ANSYS that is consistent with the physical structure of the drytype transformer,and the accuracy of the model under the rated operating conditions is verified.Moreover,the interturn short circuit fault occurs at different locations set by the external circuit of the coupling model and distribution characteristics of electromagnetic parameters is analysed when a single interturn short circuit fault occurs in the winding of dry-type transformer.Finally,the transient characteristics of electrical parameters such as the power loss factor and change rate of active power loss are obtained as sensitive characteristic state quantities,and the conclusion provides a theoretical basis for the real-time online monitoring of interturn short circuit faults in dry-type transformers and the improvement of winding anti-short circuit capability.