Analysis of Vibration Signal for Power Transformer On-Load Tap Changer (OLTC) Condition Monitoring

Vibration measurement has been used for power transformer's On-Load Tap Changer (OLTC) condition monitoring. In this paper, a signal processing method based on Savitzky-Golay filter is developed. The proposed method is applied to process a series of vibration signals measured from an OLTC when the OLTC operates throughout a number of its tap positions and subsequently evaluate the condition of these tap positions. Savitzky-Golay filter extracts the information embedded in the originally measured signal without latency in time. As such, it transforms effectively complicate feature of vibration signal into a simplified form of envelope curve. After being processed by Savitzky-Golay filter, the vibration signals corresponding to different tap positions are compared. The comparison results help to understand the characteristics of vibration signals for monitoring the mechanical condition change in OLTC.