The offline setting calculation of distance protection of EHV transmission line is a complicated and error-prone systems engineering

and needs to be coordinated with operation mode

adjacent lines and component protection. For this reason

the offline setting principles and defects of the current distance protection is sorted out

the curve functions about reliable coefficient and sensitive coefficient is designed

and the features of zero-sequence current compensation coefficient under different operation modes is analyzed to research the error of the scope of protection under the setting with single value of zero-sequence current compensation coefficient. The scheme is proposed to complete self-setting and cooperation of each section of distance protection via the original parameters of line and system and the curve functions. It can avoid the error of human setting. In addition

the simulation results of numerical example show that the operation mode and the corresponding zero-sequence compensation coefficients can be determined and calculated automatically by collecting information of relevant device to promote the effective scope of distance protection. In this way

the operation performance of distance protection is always at its best.