基于不同傅里叶算法之间相似度的励磁涌流鉴别方法

利用半波傅里叶算法计算的差流基波幅值与绝对门槛值相比较来鉴别励磁涌流和内部故障电流,存在定值整定困难的缺点.提出了一种改进算法,利用全波和半波傅里叶算法计算的差流基波幅值之间的波形相似系数进行励磁涌流鉴别,克服了原方法的上述不足.理论分析和大量动模试验表明:该方法能够可靠区分励磁涌流和变压器内部故障电流,并对对称性励磁涌流具有较好的识别效果,在空载合闸于内部轻微匝间故障时,差动保护仍能快速动作出口.

Novel Identification Method for Magnetizing Inrush Current Based on the Comparability of Different Fourier Algorithm

It is difficult to set the value by comparing the amplitude of differential current from half wave Fourier algorithm and absolute threshold wlue to identify magnetizing inrush current from inside fault current. Hence this paper presents an improved method to solve the problem, taking the advantage of similar coefficients of differential current magnitudes calculated by full-wave and half-wave Fourier algorithm. Theoretical analysis and dynamic simulation results indicate that the proposed method can distinguish magnetizing inrush current including symmetrical inrush current from internal fault current. The transformer differential protection based on the above criteria can trip rapidly and reliably even if transformer is switched on with slight internal turn-to-turn fault.