With a high voltage level and large capacity

the main wiring and voltage regulation mode of the 1 000 kV transformer are markedly different from those of a 500 kV transformer. Thus the protection configured for an ultra high voltage (UHV) transformer differs from traditional transformer protection. Based on an analysis of the UHV transformer primary structure

this paper presents a protection scheme suitable for the UHV transformer. In order to solve the problem of differential protection malfunction presumably due to the low secondary harmonic content in the regulating transformer’s differential current during the main transformer no-load closing process

the inrush current identification scheme is optimized for the compensation transformer and the regulating transformer. The correctness and validity of the UHV transformer protection configuration and the improved solution for inrush current are proved by dynamic simulation and field operation.