Abstract: An intelligent fault diagnosis and operator support system targeting in the safer operation of generators and distribution substations in power plants is introduced in this paper. Based on Expert Systems (ES) technology it incorporates a number of rules for the real time state estimation of the generator electrical part and the distribution substation topology. Within every sampling cycle the estimated state is being compared to an a priori state formed by measurements and digital signaling coming from current and voltage transformers as well as the existing electronic protection equipment. Whenever a conflict between the estimated and measured state arises, a set of heuristic rules is activated for the fault scenario inference and report. An included SCADA helps operators in the fast processing of large amounts of data, due to the user-friendly graphical representation of the monitored system. Enhanced with many heuristic rules, being a knowledge based system, the proposed system goes beyond imitation of expert operators’ knowledge, being able to inference fault scenarios concerning even components like the power electronic circuits of generator excitation system. For example, abnormal measurements on generator’s terminals can activate rules that will generate fault hypothesis possibly related to an excitation thyristors abnormal switching operation.
