New Mitigating Measures against Core Saturation by Series of Additional Grounding Resistance from the Point of View of Network Configuration

High current of HVDC grounding electrode will induce a high potential in the nearby substation ground grid if the soil resistivity is high. Once there are potential differences among the ground grids, direct current will flow through the neutral grounded transformer. If the direct current through transformer winding is high enough core saturation will occur. The paper presented a method of series of additional resistance between the transformer neutral point and ground grid from the point of view of network configuration. A novel optimized algorithm is adopted in order to calculate the grounding resistance. Method presented in the paper is tested with China South Grid data. Results show that current through transformer neutral point can be reduced greatly and thus core saturation can be avoided