Clustering transformer reactive power losses due to geomagnetic storm disturbance bring about voltage stability problems in power systems. In order to reduce these reactive power losses generated by grounded transfomers due to geomagnetically induced current (GIC)

this paper proposes a method for optimizing and controlling the multi-transformer reactive power losses by installing series resistors in the neutral point of the transformers. Firstly

the generation mechanism of the GIC and the reactive losses resulting from geomagnetic storm disturbance and the relationship between GIC and grounded resistors are analyzed. Secondly

the objective function of minimizing reactive power losses and grounded resistance are developed. Then the grounded resistance limits and constrains for normal operation of power systems are considered according to the stipulation on grounded resistance and stable operation range of power systems in the national standards. Finally the non-dominant sorting genetic algorithm (NSGA-Ⅱ) is used to solve the model. The GIC Benchmark model is taken as an example to optimize the transformer’s reactive power losses resulting from GIC with the proposed model and method. The results show that the method can effectively reduce the reactive power losses due to geomagnetic storm disturbance.