For zero sequence current differential protection phase selection element influenced by load current leading to low sensitivity in high impedance ground fault conditions

this paper puts forward a zero sequence differential protection phase selection element based on the sequence component. The phase selection element consists of three parts: to distinguish between single-phase grounding fault and two-phase high impedance ground fault using the similarity in strength of negative sequence to zero sequence differential; using phase relationship between positive sequence and negative sequence differential current to distinguish between single-phase grounding fault and two-phase grounding fault; using differential criterion of low restraint coefficient to prevent unbalanced zero sequence current by outside three-phase short circuit. A simulation model is developed and verified in RTDS

the results showing that: the phase selection element proposed is not affected by overload

can accurately select single-phase grounding fault without compensation

and ensure the higher sensitivity than zero sequence differential protection to trip out the faulty phase of zero differential protection.