A Novel Busbar Protection Based on Fault Component Integrated Impedance

This paper describes a novel principle for protecting busbars. The principle uses the ratio between the fault component voltage and the fault component differential current of the busbar to detect faults, which is defined as the fault component integrated impedance in this paper. The fault component integrated impedance of an external fault reflects the capacitance impedance of the busbar whereas that of an internal fault reflects the parallel connection result of the impedances of all the feeders connected to the busbar. As a result, the magnitudes of the integrated impedances are quite different between an external fault and an internal fault. According to such a characteristic, the criterion of fault detection is put forward, which has the inherent immunity to the impact of current flowing out when a fault occurs in the protection zone of the breaker-and-a-half busbar and is insensitive to fault resistance. The impact of the current transformer (CT) saturation on the proposed principle is discussed in this paper. Following the changes on the argument of the fault component integrated impedance, a feasible CT saturation detection algorithm is presented. EMTP simulation results verify the sensitivity and reliability of the proposed principle.