Figure 3 presents the methodology used to perform wide-area oscillation assessment and trending. We collected information of generation mix and load mix for the past years primarily from the Energy Information Administration https://www.eia.gov/consumption/.

We also collected ambient PMU phasor data of the past years. We performed oscillation detection and analysis using the Mode Meter tool to scan the collected PMU phasor data and estimate the oscillation modes. Based on the past generation/load mix information and the oscillation modes at the same past period, correlation analysis was performed to determine the oscillation trends with respect to generation/load mixes.

Meanwhile, we also collected and developed North American power grid models (power flow + dynamic) of the past years and analyse oscillation modes by simulating a set of credible oscillation events selected from the past years. The oscillation modes from this model-based simulation was compared to and contrasted with the PMU-based mode estimates to validate the accuracy of the developed North American power grid models.

Finally, the validated North American power grid models was used to analyse the oscillation modes by simulating a set of future scenarios framed with estimated future generation and load mixes. Sensitivity analysis was also performed to investigate how oscillation modes would vary with respect to future evolution of generation and load mixes.