Modeling Ground Fault Impact on Adjacent Healthy Feeders in Distribution Networks

Traditionally, in simulation of electrical networks, the ground resistance is modelled by a single resistance at the fault point. In addition, in SLG (single line to ground) fault occurrence all shunt capacitances of the faulted phase are assumed short circuited, and are not included in the calculations. This paper outlines a new model to estimate the role and the impact of the earth in line-to-ground faults in distribution networks, including OHL (overhead lines) or cables, which takes into account the fundamentals of current field distribution in the earth. The proposed model can be utilized to simulate line-to-ground faults, as well as assess how a faulted feeder affects a healthy feeder at the faulted point on earth, no matter if those feeders have different voltage levels and even different energy sources (they come from the same substation or not). This model may declare maloperations of the traditional protection methods such as ZSC (zero sequence current) measuring and even longitudinal differential protection scheme (ANSI 87L) against SLG faults on adjacent feeders.