The starting of EHV power grid is a complex and cautious operation

which decides the security of entire power grid.To work out reasonable and effective starting scheme

this paper introduces the wiring system of a 750 kV substation and its interconnected substations

and comprehensively analyzes the idle line’s closing overvoltage

the collocation of system’s relay protection

and the 750/330 kV electromagnetic loop in the starting phase of the 750 kV substation.Correspondingly

the idle line’s closing overvoltage is restricted

the requirement for setting relay protection in the starting phase is proposed

the effect of electromagnetic loop is reduced by controlling provincial-level section current

and the safety precautions for the starting phase are worked out.This project has been accepted by the State Grid Corporation.This study may provide a reference for further development of intelligent power grids

especially for research on starting of EHV grid systems.