For longitudinal differential protection of transformer

the starting current should avoid the influence of unbalanced current which is caused by the regulation of switch gear for on-load tap changer during the normal operation. When adjusting the wide range of switch gear

the sensitivity of differential protection would be influenced by high setting of the starting current. It is proposed that the gear position information could be obtained through the GOOSE network for the smart substation

and then the balance coefficient of the differential protection is adjusted automatically based on its actual gear position to eliminate the unbalanced current caused by gear position adjustment during the normal operation. Meanwhile

the tuning method of differential protection based on GOOSE network is proposed

which reduces the starting current and ratio restraint coefficient and improves the operation characteristics of differential protection. The simulation results show that the improved scheme can enhance the sensitivity and quickness of the differential protection of transformer.