A Novel Busbar Protection Method Based on Polarity Comparison of Superimposed Current

This paper proposes a novel busbar protection method based on the polarity comparison of superimposed current. Analysis shows that all lines connected to the faulted busbar have the same polarities for the superimposed currents in case of an internal fault to busbar; but for a fault occurring on any one of these lines, the polarity on the faulted line is opposite of those on healthy lines. According to this important characteristic, the busbar protection criterion can be established. To improve the reliability of the busbar protection method, waveforms of superimposed currents are integrated within a short time after the fault. Moreover, a new phase-mode transformation matrix is proposed to realize that single aerial modulus can reflect all fault types. A real 500-kV substation busbar model was built in PSCAD to evaluate the performance of busbar protection. Simulation results demonstrate that the proposed protection method has good adaptability, fast operation speed, and high reliability. In addition, its performance is rarely influenced by the fault initial conditions, series compensation, and CT saturation, etc.