Condition monitoring of a power station

The aim of this study is to obtain a signature of the aging level of the various power apparatus in a generating station, with the view to initiate a condition-based maintenance (CBM) program. On-site off-line condition monitoring was carried out on a section of the station consisting of a 300 MVA, 16 kV 3φ generator 7, a 300 MVA, 16/230 kV oil-filled step-up generator transformer T/F 7, a 20 MVA, 16/6.6 kV unit service transformer, a 2.17 MVA, 16/0.6 kV exciter transformer, about 100 m of a 3φ, 230 kV underground pressurized oil-filled cable and a 3φ, 230 kV SF₆ gas insulated switchgear (GIS) system. The study is focused on recovery voltage measurement (RVM), polarisation current measurement (PCM) and frequency response analysis (FRA). From the test measurements and analysis, it is shown that for composite insulation such as that used in transformers, the extended Debye model describes well the conditions of the insulation. For solid insulation used in a generator, the universal fractional law appears to be more suitable. Furthermore, from FRA measurements carried out on two transformers, it is shown that a fault on the HV winding of one of the transformers was identified