基于纳秒级IFRA方法的变压器绕组变形检测研究

Investigation of nanosecond impulse frequency response analysis system for power transformer winding displacement detection

脉冲频率响应分析法(IFRA)相比广泛应用于离线检测的扫描频率响应分析法(SFRA)在变压器绕组在线监测中有更好的适用性。目前,离线IFRA方法的激励脉冲波形特征尚未标准化,其可靠性、灵敏性、重复性需要深入研究。通过实验提取了适合于变压器绕组变形IFRA检测的激励脉冲波形特征,采用分频段分层小波阈值去噪提取IFRA频响曲线。在一台配电变压器上模拟了三种程度的轴向绕组变形,在两种接线方式下,均依次用IFRA方法和SFRA方法进行检测,并用斯皮尔曼相关系数和欧式距离对IFRA频响曲线进行量化分析,验证了纳秒级IFRA方法的可靠性和灵敏性,并进行了重复性验证。

A large amount of studies have shown that compared with sweep frequency response analysis （ SFRA）, the impulse frequency response （IFRA） is feasible for online condition monitoring of power transformer winding deforma- tion, while nowadays, even offline IFRA still has many drawbacks, e.g., the features of the injected impulse are not standardized and the sensitivity, reliability and reproducibility of IFRA are in question. In this paper, the features of impulses suitable for IFRA is extracted, and a novel de-noising method based on threshold wavelet de-noising is de- signed to extract appropriate IFRA response curves. Three levels of axial displacements were experimentally simulated on a distribution transformer. Both the IFRA system and a commercial SFRA analyzer were applied to obtain the fre- quency responses of the transformer at each fault level. Both the IFRA and SFRA measurement were conducted twice with two different connection schemes. Correlation coefficient and Euclidean distance are employed for the interpreta- tion of IFRA frequency responses. The reliability, reproducibility and sensitivity of the developed IFRA system are verified through experimental studies.