Alarm management in permanent PD monitoring for generators

Permanent Partial Discharge Monitoring (PDM) systems were installed in several generators in South America from 2009 to 2011. The installation fell within a long term project envisaging the installation of PDM systems in several generators placed in different power plants. All PDM units send automatically data and alarms to a Central Unit (CU) placed in the utility headquarter. Through the use of Time Frequency (TF) separation tools it is possible to reject noise and disturbances, as well as to separate on line multiple PD sources and tune proper alarm logics for each type of detected PD phenomenon without being affected by the significant on-line noise and disturbances. In addition, different criteria can be used to evaluate the trend of PD phenomena depending on PD source nature, i.e., if they are relevant to microvoids, slot, stress grading, bar to bar, delamination or corona. Furthermore multiple PD activities occurring in the same phase can be dealt separately avoiding false alarms coming from the sum of the statistical parameters relevant of each PD source.