Wind Power Plants and System Operation in the Hourly Time Domain: Preprint

Because wind is an intermittent power source, the variability may have significant impacts on system operation. Some studies have shown that this impact on regulation is not significant, but the impact on load following requirements has not yet received much attention. Part of the difficulty of analyzing the load following impact of wind is the inadequacy of most modeling frameworks to accurately treat wind plants and the difficulty of untangling causal impacts of wind plants from other dynamic phenomena. This paper presents a simple analysis of an hourly load following requirement that can be performed without extensive computer modeling. The approach is therefore useful as a first step to quantifying these impacts when extensive modeling and data sets are not available. The variability that wind plants add to the electricity supply must be analyzed in the context of overall system variability. The approach used in this paper does just that. The results show that wind plants do have an impact on load following, but when calculated as a percentage of the installed wind plant capacity, this impact is not large. Another issue is the extent to which wind forecast errors add to imbalance. Although load forecasts are generally more accurate than wind forecasts, they are also imperfect. The relative statistical independence of wind forecast errors and load forecast errors can be used to help quantify the extent to which wind forecast errors impact overall system imbalances. A case study is developed to illustrate the approach and to provide some quantitative results.