Probabilistic Assessment of Generator Failure Using the Analytic Hierarchy Process (AHP)

A combination of diagnostic techniques was carried out for a 232 MVA hydro-generator stator. These techniques included quality assessment of the electrical contact between semi-conductive (S/C) coating of stator bars and the magnetic iron core, partial discharge (PD) measurements, polarization and depolarization currents and finally stator bar dissection. The analytic hierarchy process (AHP), a multi-criteria analysis approach, was used in order to combine the results of diagnostic methods and draw conclusions on the most probable failure cause. The AHP method enables one to systemize experts reasoning in a logical framework and to detect incoherence when it appears. The results lead to the same conclusion than the expert group for this specific case study.