Ground fault protection scheme using leakage current in ineffectively earthed power systems

Traditional protection schemes are difficult to detect and isolate grounding faults in ineffectively earthed power systems, especially to detect generator stator grounding faults with selectivity in Multi-Generator-System. In order to improve them, A novel ground fault protection scheme based on leakage current in ineffectively earthed power systems is proposed in this paper. The difference of leakage current before and during fault is nearly zero in external single-phase- ground fault conditions, but is large in internal faults. The leakage current difference can thus be applied to detect faulted feeders and faulted generators in neutral ineffectively earthed power systems. The protection scheme is presented, and the protection device is also developed in this paper. EMTP simulation and experimental results show that the proposed protection scheme can correctly detect ground fault in feeders and generators with high reliability.