Adaptive transmission relaying concepts for improved performance

Concepts for adaptive protective relaying of transmission lines are presented. These include changes in online relay settings, relay characteristics, or logic in response to power system or environmental changes, or as a result of operating experience. Such changes as line-out or generator-out contingencies, which affect fault current distributions and degrade the system´s security level, initiate adaptive protection system responses. Adaptive relaying is shown to be capable of improving relaying reliability and power system security and of achieving better utilization of transmission facilities. Most of the concepts require a hierarchical computer system, involving front-line parallel processors, a substation host, and remote central processors, all linked by channels that transmit data or relaying changes prior to or after a disturbance. It is suggested that maximum value from adaptive relaying will result from integration with existing or planned substation control and data acquisition functions and interfacing with the central energy management system (EMS). Emphasis is placed on use of interim hardware approaches to allow evolutionary development