Providing explanations in a real-time expert system for control center operator assistance

Artificial intelligence techniques have been used for solving power systems problems for some years now. Expert systems in particular were of increasing importance in this area. Nevertheless, conceptual expert systems' capabilities have not yet been totally explored. Their ability to represent knowledge in a symbolic form thus allowing the explanation of its every behavior, justifying it with the knowledge it encodes is an example of neglected expert systems' possibilities. Regarding expert systems with real-time design requirements, the enabling of effective explanation features imposes several important constraints that must be taken into account. This paper presents an explanation mechanism that has been designed and implemented to be used by SPARSE, an expert system for intelligent alarm processing and power restoration aid which is running online in a Portuguese transmission control center. This explanation mechanism is intended for use in the real-time expert system with minimum of disturbances. It is also intended to work as a server, making explanations available to any application that requires them, be it a graphical user interface, a tutor module or any other.