Directional Comparison Protection Over Radio Channels for Subtransmission Lines: Field Experience in Mexico

In this paper, we first review the need for communications-assisted protection of subtransmission lines, describe the communications channels available, and compare applicable protection schemes. We show the advantages of directional comparison protection over digital point-to-point radio channels for this application. Later we present a summary of the applications of directional comparison protection over radio channels in Mexico. We also provide statistical data on the field performance of protection schemes and radio channels installed in Mexico. We then present and discuss several cases of protection scheme operation for actual faults. Finally, we provide guidelines for applying directional comparison protection over radio channels to subtransmission lines.