Expert systems for telemetry processing [of power system data]

The National Grid Company has developed two expert systems for telemetry processing. In each case the object is to reduce the flow of information to the engineer. Firstly, the alarm handling and fault analysis expert system (AHFA) is designed as an online tool for an area control centre, where it can diagnose multiple simultaneous faults in real time from switching indications alone. Diagnosis is reported incrementally, as each telemetry message arrives-there is no fixed `time window´ to wait for all messages to arrive, and there is no need for a simulation process, which would otherwise further delay the response. Secondly, the automatic fault record analysis expert system (AFRA) is designed to assist the offline analysis of substation fault records, primarily by filtering out cases where there is a normal fault and the protection has operated correctly. AFRA first analyzes analogue waveforms for evidence and timing of any fault and then classifies it, after which the millisecond-resolution sequence and timing are checked for the event signals, from protection through relays to circuit breaker switchings