Ultra-Fast Busbar Protection by Applying Improved ACUSUM

This paper presents a new method for fast busbar protection based on online improved ACUSUM of current signals at the point of current transformers (CTs) in a substation. In this method high frequency components of fault current are extracted by applying online improved ACUSUM and then the results are processed by the proposed decision rule to discriminate external faults (bay faults and line faults) from internal ones. According to the simulation results of a 400 kV substation model in EMTP/ATP-Draw software, the proposed algorithm has high security and dependability in discrimination between external and internal faults and has a very fast operation and it is immune to fault type, fault inception angle and fault resistance.