Research on non-fault-phase current characteristics in grounding fault in power transmission grid

When grounding fault occurs in power transmission line in neutral-point grounded system, fault current of the fault phase tends to increase dramatically. In the meantime, the amplitude and phase of the current of non-fault phase also changes abruptly in some degree due to mutual inductance between phases. Firstly, by building model with complete electrical parameters based on induction between phases, this paper illustrates current characteristics of non-fault phase when single-phase grounding occurs in system with neutral-point solid grounding using physical conception. Then, RTDS model is built incorporating parameters of actual system to verify the accuracy and validity of the analysis model with complete electrical parameters using real-time simulation. In conclusion, amplitude and phase of non-fault phase is influenced by load condition, position of fault, system impedance, line impedance, etc., which offer favorable references for judging grid fault characteristics and positioning of fault in a fast and effective way.