Analysis of the effects nonlinear loads have on the lifetime of generator sets

Tactical generator sets are utilized for military applications to power essential equipment as well as personal electronics. Nonlinear loads are becoming increasingly present due to the advancements in power electronics for high efficiency power conversion. However, nonlinear loads also introduce voltage and current harmonics into the power system which in turn has negative effects to the generator, potentially reducing the lifetime of the generator set. The harmonics introduced into the system causes an increase in power losses on the stator windings thus increasing the operating temperature of the components in proximity. When the operating temperature surpasses the temperature rating of the insulation of the stator windings, the aging of the insulation material is accelerated leading to premature deterioration. This thesis investigates the effects nonlinear loads have on the lifetime of two different tactical generator sets. A testbed comprised of various nonlinear load profiles was designed and developed and the generator sets were operated for extended periods under heavy nonlinear loads. Analysis was conducted on the voltage and current harmonics introduced into the system as well as the temperature rises in the stator windings during operation. Stator winding temperature data is then utilized to determine if nonlinear loads cause an accelerated deterioration of the stator winding insulation, reducing the lifetime of the generator sets.