This report analyses the impact of generator size (geographic footprint and installed capacity) on ramp rates for solar and wind farms in Australia. The findings can help to inform on-grid and off-grid applications; however, developers of off-grid hybrid power stations have the most to gain from the presented outcomes.
Understanding how quickly solar and wind farms can “ramp” their generation up or down in response to variable weather conditions is relevant to understanding how a high penetration renewables grid (from off-grid applications to the NEM) can best operate, and the requirements for storage or backup generation to account for intra-day weather variability. Ramp rates are one of the factors in determining whether a grid will remain stable after a sudden drop and then increase in generation due to thick cloud cover passing quickly over a solar farm or change in wind speed at a wind farm.
This new empirical analysis on wind and solar “ramp rates” will assist developers and operators in being able to better optimise the design of hybrid power systems and the appropriate storage, forecasting and other strategies required to best manage generation variability. This study analyses high frequency (i.e., 4 second) dispatch data from 2020 at 54 grid-connected solar and wind generators to improve the understanding of the relationship that exists between size (i.e., geographical footprint and capacity) and ramp rates. We report on the probability distributions of 4-second, 6-second, 60-second and 5-minute ramp rates.
The findings can help to inform on-grid and off-grid applications; however, developers of off-grid hybrid power stations have the most to gain from the presented outcomes. Off-grid power stations can achieve higher renewable energy fractions if their design accounts for ramp rates at short time intervals (i.e., sub 5-minute). Previously, there has been limited analysis of empirical evidence that quantifies ramp rates for variable renewable energy (VRE) generators at short time intervals.