Transmission Line Damping Effects on Power System Inertia Response

As the effects of climate change are becoming an ever-growing concern, countries around the world are rapidly increasing the participation of renewable generation to reduce CO2 emissions. A large portion of this generation is interfaced to the power system through power electronic converters, and as their participation increases it begins to have undesirable effects on frequency stability. As the increase in their participation begins to displace traditional synchronous generation through end of life and/or early decommissioning, the power system inertia will decrease. This increases the rate of change of frequency (ROCOF) making the frequency of the system respond quicker to power imbalances. In this paper, the damping effects of transmission lines on the inertia response of a simple power system characterized by long transmission lines is explored. The outcome sets the foundation to address concerns on the ROCOF by lowering system inertia on networks with characteristically long transmission systems and high renewable energy penetration. The results showed that for frequency disturbances, longer transmission lines result in a lower ROCOF.