Mechanical Fault Diagnostics of Power Transformer On-Load Tap Changers Using Dynamic Time Warping

An on-load tap changer (OLTC) is one of the most error-prone parts in the transformer. The stability of the entire power system will be greatly threatened if the OLTC fails. It is necessary to diagnose the mechanical fault of OLTCs. At the same time, the mechanical fault signals are not easy to collect during practical application. It is desirable to have indicators that help to access the condition of the OLTC with a small number of fault samples. This paper describes a strategy for distinguishing different mechanical diagnostics of OLTCs based on dynamic time warping. By synchronization, framing, and Fourier transform, the signal can be represented by an energy matrix, which can be used to distinguish different conditions of the OLTCs and shows the severities of the fault. Some simulated experiments are designed and in order to make the simulations close to reality, all experiments are taken in a tank which is filled with transformer oil. These experiments demonstrate that the proposed approach can effectively diagnose different OLTC faults under different fault severities.