An integrated relay for differential protection of transmission lines

This paper presents a new integrated current differential protection scheme for transmission lines. The concept of the integrated protection is firstly introduced. An integrated protection scheme based on the current differential techniques is further described, in which a specially designed protection relay with protection algorithms of multiple settings is responsible for the protection of all the line sections associated with the substation busbar. The scheme incorporates a new effective CT supervision technique based on integrated information, the significant advantage of this technique is demonstrated in the paper through simulation studies. Results show that the integrated differential protection is not only able to offer significant advantages over the conventional protection.