Short-Term Power Fluctuations of Large Wind Power Plants

Abstract

With electric utilities and other power providers showing increased interest in wind power and with growing penetration of wind capacity into the market, questions about how wind power fluctuations affect power system operations and about wind power’s ancillary services requirements are receiving lots of attention. To evaluate short-term wind power fluctuations and the range of ancillary service of wind power plants, the National Renewable Energy Laboratory (NREL), in cooperation with Enron Wind, has started a project to record output power from several large commercial wind power plants at the 1-Hertz rate. The project’s purpose is to acquire actual, long-term wind power output data for analyzing wind power fluctuations, frequency distribution of the changes, the effects of spatial diversity, and wind power ancillary services. This paper presents statistical properties of the data collected so far and discusses the results of data analysis. Although the efforts to monitor wind power plants are ongoing, we can already conclude from the available data that despite the stochastic nature of wind power fluctuations, the magnitudes and rates of wind power changes caused by wind speed variations are seldom extreme, nor are they totally random. Their values are bounded in narrow ranges. Power output data also show significant spatial variations within a large wind power plant.