This study examines how short-term variability in wind power—known as wind intermittency—affects real-time electricity system imbalances in U.S. regional power markets. The authors, Victoria Godwin and Matthew E. Oliver of the Georgia Institute of Technology and EPIcenter affiliates, analyze data from four major system operators: Bonneville Power Administration (BPA), New York ISO (NYISO), Southwest Power Pool (SPP), and PJM Interconnection. They focus on Area Control Error (ACE), a real-time metric used by grid operators to measure the mismatch between electricity supply and demand, adjusted for frequency deviations. Maintaining ACE near zero is essential for grid stability.

The authors find that a doubling of hourly wind generation variance increases average hourly ACE by 2% in BPA, 3.7% in NYISO, and 11.4% in SPP—equivalent to 1.2 MW, 1.8 MW, and 9.35 MW increases in system imbalance, respectively. PJM shows no significant effect, likely due to less granular data. They also show that sudden increases in wind generation are more likely to cause oversupply (positive ACE), while sudden drops lead to undersupply (negative ACE), confirming asymmetric operational impacts.

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