Specification of computer-aided design of transmission protection systems. Final report

The most tedious and time-consuming task for protection engineers is selecting and setting protective relays. It is shown that this and many other tasks of the protection engineer can be relieved by the computer-aided design (CAD) concept. The requirements of such a CAD system are specified. In the process, complete and precise primary/backup coordination criteria are identified for directional relays on transmission networks. Criteria are included for both overcurrent and 3-zone distance relays and for two and three terminal lines. A successful CAD system depends upon a suitable man-machine dialog, effective algorithms and convenient data management. We have begun the appropriate man-machine dialog structuring for the protection CAD system. Algorithms necessary for computer aided relay coordination have been developed. These algorithms consist of one for network analysis and one each for overcurrent and distance relay coordination. These algorithms will successfully coordinate the relays on a test system consisting of a portion of the Puget Sound Power and Light Company's 115-kV system. The results are as good or better than manual coordination by experienced engineers. It is proposed that modern data base methods be used for data management. The experimental code has been implemented using relational data base software. A relationalmore » data base design which includes all types of protection data expected to be necessary for the CAD system is provided.« less