Adaptive current protection with sensitivity independent of different type of faults

The reliability and sensitivity of the present adaptive current protection is dropped under phase-to-phase fault due to the existence of load current in non-valid grounded power systems. This paper presents a new algorithm, which can take into account of the impact of load current under phase-to-phase fault, and can convert the measured phase-to-phase fault current to the three-phase fault current at the same fault point, then the three-phase fault current is used to compare with the setting value. This method ensures the same class of sensitivity for three-phase short circuit and phase-to-phase short circuit, and the simulation verifies the flexibility and reliability.