Study on diagnosis of power transformer winding deformation through vibration signal

Abstract

As one of the most important equipment in power system, power transformer plays a major role in guarantying the safe and stable operation of power system. Among the faults in transformer, winding deformation takes a large part. Since 1970s, lots of method, such as Frequency Response Analysis, Low Voltage Impulse have been put into winding deformation detection. Among these methods, Vibration Analysis from oil tank has gained much attention through its advantage that it is closely related with the mechanical condition of winding and core and can be used in on-line monitoring. This paper based on the mechanism of transformer vibration and Fourier Transform, choose Fundamental Frequency of Vibration (FFV), Maximum Amplitude in Frequency spectrum (MAF) and Transformer Vibration Entropy (TVE) as vibration eigenvalue to indicate the mechanical condition of transformer. What's more, the failure threshold for diagnosis is acquired through 78 power transformer varying from 110kV to 750kV, single phase to three phase. Among the test results, the vibration eigenvalue from one 110kV power transformer who suffered an external short-circuit accident shows that the winding of 3 phases all have winding deformation. The conclusion and diagnosis results are proved to be effective after the transformer is sent back to the manufacturer and make a pendant-core examination. The diagnosis method for power transformer in this paper based on tank vibration can make contributions to condition monitoring.