A Critical View on the Partial Discharge Models for Various Electrical Machines’ Insulation Materials

Synchronous generators (SGs) play a vital role in energy production as well as in the industry. Their insulation system, where epoxy resin and mica dominate among the most common insulation materials, plays the most significant role in proper operation of a SG and in extending its lifetime. Epoxy resin and mica have characteristics, which make them very good materials for a reliable SG insulation. Partial discharges (PDs) are one of the most serious problems, because they can cause problems on the SG insulation. PDs are both a symptom of insulation degradation and a means to identify possible insulation faults. Thus, it is very important to detect PDs with offline or/and online PD Tests. A comparison of different MATLAB/Simulink PD models of PDs occurring in insulation materials is presented in this paper. Epoxy resin, mica, and a combination of these two insulation materials are used for simulations in order to investigate factors, such as the applied voltage and the geometry of a void inside the insulation, and how these affect the condition of the materials and are related to PDs and flashover voltages, which may also appear in electrical machines’ insulation. The aforementioned factors are examined in order to evaluate which of the materials is affected the most and which one is the most proper for SGs’ insulation system.