Mitigation of adverse effects of gics on transformers using look-up table controlled ground resistance

Geomagnetically induced currents (GICs) in power systems can cause problems ranging from transformer overheating to tripping of protective devices and voltage instability. This paper presents a new approach by using a lookup table (LUT) controlled resistance to suppress the GIC flowing through the neutral of transformers. The performance of the proposed method is compared with that of the currently adopted method, i. e, the fixed-capacitor method. In this work, the tested network consists of a single synchronous machine connected through a step-up delta/wye transformer, transmission lines, and another step-down transformer to an infinite bus. The MATLAB/SIMULINK software is utilized to carry out simulations. Simulation results show that the proposed method is able to stabilize the system under GIC events as well as mitigate the zero sequence current flowing during unsymmetrical faults. Moreover, the performance of the proposed method is better than that of the conventional method.