Model-parameter identification based bus-bar protection principle

A novel model-parameter identification based bus-bar protection principle is proposed. An inductance model can be developed when the internal fault occurs on bus, and the inductance and the resistance of the model are taken as the unknown parameters. By calculating the equivalent instantaneous impedance and the dispersion of the parameters, and utilizing their difference, the external fault and the internal fault with different current transformer (CT) saturation degrees can be distinguished correctly. According to this, a new criterion with self-adaptive restraint characteristic for bus-bar protection is put forward. As the new principle is suitable for non-periodic component, fundamental component and harmonic component, it can operate more rapidly compared with the traditional bus-bar protection principles. Moreover, it can be applied to the bus-bar with one-and-a-half breaker arrangement and the protection performance won't be affected even when an internal fault occurs with current flowing out the bus. Simulation results show that the presented principle has high sensitivity and reliability.