变压器和应涌流的理论探讨

Theory Analysis of the Sympathetic Inrush in Operating Transformers

在线性化简化的基础上,建立了两台单相变压器并联和级联运行模型,推导了当一台变压器 正常运行,另外一台并联或级联变压器空投充电时,两台变压器的磁链解析表达形式,定性分析了 正在运行的变压器可能发生饱和现象以及和应涌流产生及影响的机理。同时,在利用分段线性特 性考虑磁化特性的情况下,通过数值仿真进一步分析了空投充电变压器的剩磁与合闸角、系统阻抗 参数对运行变压器和应涌流幅值及饱和速度的影响,仿真结果验证了分析结论,为和应涌流导致变 压器差动保护误动的分析以及认识和应涌流的本质奠定了基础。

A mathematical model is developed for two transformers in parallel and cascade operation to analyze the variation of their flux linkages based on the linearized magnetic circuit. The mathematical representations of flux linkage in the operating and energized transformer are deduced and it is analytically explained that the operating transformer may be saturated and the sympathetic inrush is produced and affected in it, after another adjacent transformer is energized in parallel or in cascade. At the same time, by adopting the piecewise linearized magnetization characteristics, the influences of such factors as the residual flux linkage, switching time, parameters of the connected power line on the amplitude of sympathetic inrush and the time of transformer saturation are further analyzed by numerical simulation. The analytic conclusions are verified by the results obtained. These analyses provide a theoretical basis to the investigation on the mal-operation of transformer differential protection and an understanding of the sympathetic inrush itself.