Abstract
Reviewing the development progress of power system relay protection technology, the paper describes the achievement of micro computerized relay protection technology and present sits development trends, is the integration and artificial intelligence on computer, network, relay protection, control, measurement and data communication technologies.
The timing and impedance relays on the tectonic movements and the principles of how they are to achieve their functions. Power network requires that protective relaying should be reliable, selective, speeding, and sensitive. People engage in it need to coordinate separately under different circumstances. The paper discusses the cause of backup protection on 110kV power line losing coordination and how to set kinds of protective equipment , in order to make them operating safely in accord with demands of power network.
Keywords relay protection;
instantaneous over current protection;
zero sequence over current protection;
setting calculation