Impact of Wind Energy on Hourly Load Following Requirements: An Hourly and Seasonal Analysis; Preprint

The impacts of wind energy on the power system grid can be decomposed into several time scales that include regulation, load following, and unit commitment. Techniques for evaluating the impacts on these time scales are still evolving, and as wind energy becomes a larger part of the electricity supply, valuable experience will be gained that will help refine these methods. Studies that estimatedthe impact of wind in the load following time scale found differing results and costs, ranging from near zero to approximately $2.50/megawatt-hour (MWh). Part of the reason for these differences is the different interpretation of the impacts that would be allocated to this ancillary service. Because of the low correlation between changes in load and wind, long-term analyses of the load followingimpact of wind may find low impacts. During the daily load cycle, there is a tremendous variability in load following requirements in systems without wind. When significant levels of wind generation are added to the resource mix, relatively small changes in wind output can complicate the task of balancing the system during periods of large load swings. This paper analyzes the load followingimpacts of wind by segregating these critical time periods of the day and separating the analysis by season. The analysis compares wind generation at geographically dispersed sites to wind generation based primarily at a single site, and for a large penetration of wind (more than 20% wind capacity to peak load).