Expert systems for protection grading [of power systems]

The author describes a power system protection coordination package was developed some years ago and now includes an expert system which can point out the errors after the user has carried out the design. Data input/output procedures have also been made as simple and straightforward as possible and a menu is very suitable for parameter modifications and interacting different modules within the package. The choice of options could be assessed by using a menu. By means of digital simulation, the users can be sure whether there is a proper coordination between the primary protection and backup protection. In addition, the package can perform protection coordination automatically. The automatic analysis is only an auxiliary function to understand the basic concept of coordination