Research on a novel digital transformer protection method based on the OCT

This paper describes a new approach for transformer differential protection based on OCT that ensures security for external faults, inrush, and overexcitation conditions and provides dependability for internal faults. This approach combines harmonic restraint and blocking methods with DC content blocking. In this paper, the digital signal processor (DSP) is applied to improve computation and render fast protection feasible. The novel transformer protection system interface construction, hardware structure, software algorithm are discussed. Performance analysis shows its has distinguish advantages over the traditional transformer protection.