A new fast method for improvement of power transformer differential protection based on discrete energy separation algorithm

Abstract Differential protection is one of the most widely used protections in power transformers. The challenges associated with this protection are distinguishing the inrush current, overexcitation, and external fault conditions from internal and winding faults. So far, various methods have been proposed to prevent differential protection from mal-operation, which are not necessarily simple to implement and do not guarantee the proper performance in all scenarios. This paper proposes a new method based on the discrete energy separation algorithm to improve differential protection. The proposed method consists of two sections. The first section detects internal disturbances from external faults, and the other distinguishes the inrush current and overexcitation from internal and winding faults. One of the advantages of the proposed method is the parallel employment of these two sections in the logic of the method, which reduces the detection time. Moreover, other advantages such as the fast detection speed (1.5 ms), simple implementation, and low computational burden make it possible to implement the method in real-time. The simulation results show the appropriate efficiency of the proposed method in detecting all disturbances even in noisy conditions and saturation of current transformers.