Wide-Frequency Finite Element Based Model for Partial Discharge Pulse Propagation in Stator Winding of Generators

Condition monitoring of generators is one of the main keys to reduce outages and keep the system stable during disturbances. The partial discharge (PD) test is among the most reliable tools for diagnosing generator insulation defects in the early stages. However, various studies show that it is impossible to correlate the measurement results with the apparent charge of the occurred PD in the generator winding. Therefore, no specific threshold can be set for the harmful PD activities in the generator stator windings. Modeling the stator winding for PD pulse propagation helps to interpret the PD test results properly. In this regard, this paper presents a finite element method (FEM)-based model with acceptable accuracy in a wide frequency range. Practical laboratory tests performed on stator bars are used to validate the model. The results and findings of the proposed model are fully matched with practical tests. Also, the proposed model covers the features obtained for PD pulse propagation in previous experimental studies. The proposed model can be employed to investigate the PD pulse propagations at both low and high frequencies, which is an important tool to analyze the results of a PD test correctly.