Simple and Adaptive Busbar Protection Scheme Considering CT Saturation Effect

Abstract

his paper shows novel differential busbar protection proposal based on new and simple transform, called Akrap which joins the advantages of differential technique and Akrap transform. Akrap is a transform used to extract the arriving waves of the fault signals. Akrap is applied to both Sum of the currents which enter the busbar and sum of the currents which leave the busbar. The proposal uses current signals of all the links joined to the busbar. Ratio signal is calculated for internal/external faults discrimination. An innovative amplification process is proposed to be applied on the Akrap relaying signals. Such process increases the sensitivity and the stability. As the amplification of the Akrap signals is achieved during abnormal operation and keep the signals unity during normal operation. The studied system was modeled using the EMTP software. Huge numbers of fault cases with broad fault parameters variant are done to evaluate the protection proposal. The proposed protection fulfills the requirements of high speed, sensitivity even a high resistance faults, reliability in discrimination faults located in the zone and out of the zone and avoids early and severe CT saturation effect. The proposed scheme isn't affected by the fault conditions such as fault position, fault resistance, inception time or fault type. Also, it isn't affected by load switching.