oo load tap changers (OLTCs) play an important rolein regulating reactive power and stabilizing grid voltagein power systems [1]. According to statistical reports, OLTCinducedtransformer faults account for more than 20% of thetotal faults, and mechanical faults account for more than 90%of the total faults [2]. In addition, high-voltage direct currenttransmission systems raise the requirements of reliability, e.g.,the frequent voltage regulation operation of OLTCs for converters.With the rapid application of electric vehicles (EVs) inrecent years, there are an increasing number of novel electricalappliances and devices incorporated in the existing power grid,e.g., charging piles and energy storage devices [3]. Thesenew components inevitably bring new features and challenges