Variability assessment of solar and wind resources in Puerto Rico

The integration of bulk solar and wind generation into the electric power network of Puerto Rico introduces new operational and economic challenges. When local atmospheric conditions deteriorates and causes unexpected mismatches in short-term forecasts, the electric network will be subjected to strong active power ramp events that online generation units may not be able to support and manage. Uncertainties in the variability of the net-load prediction may result in over-commitment of rapid-response resources. Additionally, from the perspective of a variable generation developer, these events may increase the chances of curtailment. Thus, quantifying the intensity and frequency of these events in a spatial-temporal framework, and evaluating its interaction with electricity demand, should provide a better understanding of the impact that bulk intermittent generation will have on the rest of the existing generation portfolio of the island. Characterizing the variability of solar and wind ramp events in Puerto Rico, and its effect on the power system capability to adapt, is the main scope of this investigation. By synthesizing solar radiation and wind speed data sets, a one-year renewable energy time series was re-created by means of Markov Chain Processes. The spatial-temporal characteristics of solar and wind energy ramp events in the island were evaluated and the impact of these events on the existing inter-hour requirements was quantified for the 12%, 15% and 20% yearly renewable generation targets. Results have shown that predictable ramp events will create most of the challenges at sunset, mostly due to the fact that intermittent generation will ramp down continuously as electricity demand increases. Meanwhile, for the 15% and 20% targets, VG will be detrimental during off-peak hours, when base-load units are expected to be committed to their minimum operational limits.