Busbar Protection- A Solution to CT Saturation

Abstract: This work proposes a busbar protection scheme based on phase changes in positive sequence current of incoming and outgoing line current transformers (CTs). The angle differences of during fault and prefault current signals of incoming and outgoing CTs are the indicators of external or internal faults for bus bar protection. The advantage of the method is that it does not use magnitude information of the current and thus overcomes the CT saturation issues. The performance of the technique was investigated for a variety of operating conditions, for CT saturation, CT ratio mismatch, different fault inception angles, for different type of faults and for several bus-bar configurations. Keywords- Digital busbar protection, phasor estimation, CT saturation, DFT, Fault I