Grounding fault protection in distribution system based on method of the module maximum value

Fault line detection in distribution system is a problem. In this paper, method of the module maximum value is employed to analyze the electric information after the fault, and to respond the abrupt change of zero sequence currents, and through comparing the change of the zero sequence currents on all lines´ polarities and magnitudes, then the fault line can be determined. With the using of inner product, the criterion has good property of containing error, and so that it can get more high precision of fault line detection. This method is suited for various distribution systems with different neutral grounding modes. Moreover, it can be easily used in site without adjusting protective setting. EMTP simulations show that the method is effective and reliable.