C.A.E. Software for Transmission Protection System: Puget Power Experience

One major concern of a protection engineer is to achieve successful coordination of all relays in a transmission network. This tedious and laborious process is usually accomplished manually at present. In this paper we present the results of a Computer-Aided Protection System based on our experimentation with the entire 115 kV transmission network of Puget Sound Power and Light Company (Puget Power), which consists of 38 buses and 61 lines. The protection package entails algorithms for both overcurrent and distance relays. Effective man-machine interaction is provided by means of computer-graphics. Such interaction is invaluable in providing the protection engineer with both the details of coordination process and the control over this process. A novel feature of the package is the performance and analysis feature for overcurrent relays. The results for the above system are provided and the execution times for different test cases using an IBM 4341 computer system are also presented.