MICROPROCESSOR BASED TRANSMISSION LINE TERMINAL FOR PROTECTION, CONTROL AND MONITORING

The introduction of microprocessor technique in protective relaying offers new possibilities to optimize and coordinate the required functions as well as providing remote communication. This paper describes a numerical and modulaxized transmission line terminal with separate microprocessor modules for each main function such as distance protection, earth fault protection, fault location autoreclosing and fault recorder. The use of signal processors allows a full scheme, continous and parallel measurement for all functions and quantities.This gives a high performance solution which fulfills all normal requirements for both HV and EHV transmission lines as well as giving several new benefits for the user. Single processor solutions are used by the authors company and other manufacturers and can provide compact solutions also for line protection when the requirement and application permit so. A multi processor solution as this paper describes offers faster and continous processing which makes it possible to also meet the high performance requirements for HV and EHV systems. The input module is based on an A/D converter with 40 samples/period and the terminal can be used with either conventional or optical instrument transformers. The terminal can be used stand-alone and has a local MMC for parametration and reading which easily can be used by the technician or the engineer. The terminal can also communicate via an RS232 port or a fiber optic port to a PC, a printer or be a part of a complete Substation Monitoring System (SMS) or a Substation Control System (SCS). The information handling and parametration is structured to meet the requirement from different personnel categories. Three different computerized work places can be connected to the terminal for the Operator, the Relay Engineer and the Service engineer. Several software package with support programs are available for the workstations. All together this numerical terminal offers a new tool in the search for excellence in Electricity Supply and Management.