Real-time operation surveillance of a static cycloconvertor basedon waveform supervision

摘要

Conventional protection systems of large power converters offerhigh reliability in preventing destructive failures. Such systemsinclude differential and absolute current protections, under andovervoltage protections and semiconductor fuses. Also, some systems useindependent electronic monitoring to detect frequency deviations, earthcurrents and overtemperature of selected units. To improve performance alarge number of feedback signals is required. This number isproportional to the number of power semiconductors used in the convertercircuit. Therefore, the reliability of a complete and user-friendlydiagnosis system is intrinsically low. To overcome this problem anexpert system approach is proposed in this work for the surveillance ofa cycloconverter. A true on-line operation surveillance of acycloconvertor based an waveform supervision is discussed. Using thismethod, the diagnosis of the converter operation requires a reducednumber of feedback signals. Some usual abnormal and faulty conditionsare examined. Finally, selected experimental results obtained with alaboratory prototype are presented