CRITICAL TIMEFRAMES OF IMPORTANCE FOR PV FROM A UTILITY PERSPECTIVE

摘要

As solar penetrations increase, several resource attributes and timeframes are becoming of increasing importance to utility and balancing authority operators. In particular, output and variability of PV systems during summer peak demand periods, during daytime minimum load conditions in the spring and fall, and finally at very high penetrations, during periods of significant load ramps for the utility. Using historical solar resource data and load data, PV output is simulated for different configurations and capacity levels to evaluate its potential to impact grid operations during these types of timeframes. In this study, historical SMUD hourly load data is correlated to validated modeled PV output to determine appropriate on-peak capacity values by orientation, minimum load -maximum PV output correlations and frequency, and diurnal patterns of change on an hourly basis. The assessment uses 9 years of SolarAnywhere(c) 10 km grid hourly data correlated to SMUD system load data. More recent sub-hourly assessments are done for these values using recently installed ground-based solar monitoring to evaluate sub-hourly variability that may significantly impact grid operations during low-load time periods of interest. The results show that for SMUD's service territory, peak contribution from solar PV can be consistently expected to contribute between 35% and 60% of its peak rating depending on orientation during the typical peak hour ending 6PM. Periods of high PV output and low utility loads occur during approximately 15% of the 4,200 hours that PV produces energy during year in Sacramento, primarily in the springtime with a second but lower concentration during the fall. Within an hour, a few dozen days a year appear to have high variability, potentially creating issues for distribution system operators with changes exceeding 50% of rated capacity of a multi-MW system in a 1 -minute period. Finally, over the longer term, periods of significant ramps of PV in the morning and evening are likely to present challenges for existing grid balancing resources during non-summer months.