非饱和区等效瞬时电感在判别变压器和应涌流中的应用研究

和应涌流可能引起运行变压器差动保护误动.影响变压器的正常运行,但目前还没有判别运行变压器中产生和应涌的有效方法。文章根据变压器和应涌流产生的原因,利用等效瞬时电感能够正确反映变压器运行状态的特点,由非饱和区内等效瞬时电感平均值的大小判别运行变压器发生和应涌流,闭锁差动保护,防止其误动。仿真和实验结果证明该方法较二次谐波比励磁涌流闭锁判据及三次谐波比电流互感器饱和判据在识别和应涌流方面具有可靠性高、抗电流互感器饱和能力强的优点。

Application of Equivalent Instantaneous Inductance in Nonstaturation Zone to Identify the Sympathetic Inrush in Transformer

The sympathetic inrush may cause the mal-operation of differential protection for running transformer, and affect its normal running. However, there is no available effective measure to identify the sympathetic inrush at present. In this study, according to the cause of sympathetic inrush occurring and the characteristic that the equivalent instantaneous inductance of transformer can reflect its running situation, using the average of equivalent instantaneous inductance in non-saturation zone detects the sympathetic inrush, further blocks the differential protection and prevents it from mal-operation. The simulation and experimental results verify that the method have higher reliability than second harmonic restraint scheme against initial and third harmonic block scheme against saturation of current transformer, and have better immune to the saturation of current transformer. This work is supported by National natural Science Foundation of China (No. 50507014), in part by the Electrical Power Science and Technology Foundation of Xuji and in part by the Youth Innovation Foundation of the department of Electrical Engineering, Tsinghua University.