基于非饱和区等效瞬时电感的变压器励磁涌流鉴别方法

Identification of transformer magnetizing inrush based on equivalent instantaneous inductance in nonsaturation zone

变压器的等效瞬时电感能够反映其饱和程度的变化,按照差流大小将变压器的运行状态划分为饱和区与非饱和区,分析了变压器经历励磁涌流和短路故障过程中,其等效瞬时电感值在饱和区与非饱和区内的变化范围及特点,根据非饱和区内等效瞬时电感大小区分励磁涌流和短路故障的方法。该方法原理清晰、整定简单、裕度大。试验结果证明,在区内短路故障以及带故障合闸时,该方法能够快速开放差动保护;在励磁涌流时,能够可靠闭锁差动保护,并有良好的抗电流互感器饱和特性,具有工程实际应用价值。

The equivalent instantaneous inductance of transformer can reflect the change of its saturation level. The variation range and characteristic of equivalent instantaneous inductance between nonsaturation and saturation zones is analyzed,which are divided according to the differential current during the magnetizing inrush and short-circuit fault in transformer. A method is proposed to distinguish magnetizing inrush from short-circuit fault based on the average of equivalent instantaneous inductance in the nonsaturation zone. Its principle is clear,and its setting is simple and easy. The experimental results verify that the method can correctly open the differential protection in short time during internal short-circuit fault and energizing with turn-to-turn short-circuit and reliably block the protection during the magnetizing inrush. It is well immune to the saturation of current transformer and applicable in practice.