Temperature Impact on On-load Tap Changers VibroAcoustic Signals

Vibroacoustic signals based diagnosis is a promising method for monitoring the on-load tap changers (OLTC). However, the influence of temperature on the OLTC vibroacoustic signals is still not completely quantified or modeled. In this paper, the impact of temperature on vibro-acoustic envelopes registered from OLTC operations, was investigated. The data analysis focused on the maximum values and time shifting of the vibroacoustic envelopes at high frequency. Probabilistic distributions were associated with the maximum values and time shifting of vibro-acoustic envelopes. Also, mathematical models that correlate the changes in the distribution parameters with temperature were proposed. The maximum values in the envelopes showed an approximately lognormal distribution, whereas the time shifting was associated to a normal distribution. Curve fitting tools were then used to model the mean values of the maximum values and time shifting as functions of temperature. The mean maximum values showed an approximately linear relationship with the temperature. However, different patterns were identified in the analysis. Time shifting follows different probabilistic models based on changes in the direction of the operations, which shows an increase in complexity. The results of this work help in understanding the influence of temperature on OLTC vibro-acoustic signals and aid in the development of new monitoring methods.