Application of Fault Line Selection Apparatus Based-on Transient Current Principle in Small Current Grounding System of WISCO Grid

The small current grounding system is widely used in the medium voltage distribution system in China.Single phase grounding fault happens frequently in this system.So how to detect the fault line quickly and accurately is an important subject of relaying protection in the power system.Several common line selection methods are introduced briefly.The transient current principle-based line selection ways of small current grounding are analyzed and studied.The apparatus applying this principle was used in a simulation test in a 10 kV substation of WISCO grid and the test effect is satisfactory.