Considering the new developmental tendency of the state grid including hybrid AC/DC power grids

the access of clean energy

and the power electronics dominated power systems

the changed fault characteristics of modern power systems are analyzed

meanwhile

the challenges and development situation faced by relay protection technology are proposed. Based on this

the principles to be persevered for relay protection technology development are summarized. The emphatic development directions are discussed in detail

namely

the plug-and-play outdoor installation protection

the optimally configured back-up protection

the intelligent operation and maintenance system

three technical supporting platforms of relay protection; the control and protection of high voltage direct current(HVDC)transmission; the forward technologies of relay protection.