Universal transmission line protection intelligent electronic devices

The paper addresses the concept of a universal transmission line protection IED designed to meet the complex requirements for primary and backup protection under different fault conditions and power system configurations. It has a modular architecture in order to allow adaptation of the hardware and software to different transmission line protection configurations. Multiple operating principles are included and can be combined in order to ensure correct operation for any condition. The functioning of the Universal Transmission Line Protection as a communications based unit type protection using differential or directional comparison mode is described. Digital communications based permissive or blocking schemes are addressed as well. Local and remote backup operation of distance, high and low set overcurrent, overload and broken conductor detection functions are presented. The application of the universal transmission line protection to two and three terminal lines, mutually coupled lines, transmission line-transformer circuits or ring-bus and breaker and a half-configurations are discussed. Advanced breaker failure protection and reclosing with synchronism check, as well as programmable scheme logic, metering, recording and monitoring functions are described later in the paper.