Mechanical Fault Diagnostics of Power Transformer On-load Tap Changers Based on Marginal Point Distribution Coefficient

With the continuous construction of power system in China, the safe and stable operation of power system has become a very important problem. The On-Load Tap Changer (OLTC), as the only movable part in power transformer, plays an important role in the stable operation of the transformer and even the whole power system. At present, the fault diagnosis of the OLTC based on the vibration signal has become the focus of scholars. In this paper, the vibration signals of the OLTC including good condition, tap loosening, tap abrasion and insufficient energy-storage are obtained by simulating experiment. Meanwhile, in order to characterize OLTCs in different conditions, a characteristic parameter Marginal Phase Space Distribution Coefficient (MPPDC) is proposed based on phase space reconstruction technology. Furthermore, based on MPPDC and fuzzy set, a fault diagnosis strategy of OLTC is proposed in this paper. The experimental results show that based on the method proposed in this paper, the fault types of the OLTC can be effectively identified, which provides the theoretical basis for the on-line monitoring technology of OLTC.