Analysis of the impact of nonlinear loads’ harmonics on synchronous generators lifetime

Nonlinear loads are the cause of current and voltage harmonics present in the power system. Recent developments in power electronics have contributed to an increase in the number of nonlinear loads connected to the power grid. The current harmonics injected by these nonlinear loads have a negative impact on the lifetime of power system components. Harmonics contribute to the increase of the operating temperature of electrical machines, transformers and electrical cables. Synchronous generators, operating above their rated temperature rises, experience a decrease in their lifetime. The lifetime reduction is due to the premature aging behavior of the insulating material which is exposed to elevated temperatures. This thesis analyzes the impact of voltage and current harmonics on the lifetime of synchronous generators. The estimation of the reduction of the generator lifetime due to harmonics is performed in four steps. The first step is the modeling of nonlinear loads. The second step involves the computation of the additional losses created by voltage and current harmonics. The third step is the determination of the temperature rise of the windings due to harmonics. The fourth step is the estimation of the insulator lifetime percentage decrease relative to the rated lifetime.