Operating Reserves and Variable Generation A comprehensive review of current strategies, studies, and fundamental research on the impact that increased penetration of variable renewable generation has on power system operating reserves. Erik Ela, Michael Milligan, and Brendan Kirby NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Technical Report NREL/TP-5500-51978 August 2011 Contract No. DE-AC36-08GO28308 Operating Reserves and Variable Generation A comprehensive review of current strategies, studies, and fundamental research on the impact that increased penetration of variable renewable generation has on power system operating reserves. Erik Ela, Michael Milligan, and Brendan Kirby Prepared under Task No. WE110920 Cover photo is NREL PIX 19498. NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory Technical Report 1617 Cole Boulevard NREL/TP-5500-51978 Golden, Colorado 80401 August 2011 303-275-3000 • www.nrel.gov Contract No. DE-AC36-08GO28308 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. 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Table of Contents List of Figures ............................................................................................................................................... v List of Tables ............................................................................................................................................... vi Abstract ....................................................................................................................................................... vii Abbreviations and Definitions ................................................................................................................... viii Acknowledgements ....................................................................................................................................... x 1 Introduction ........................................................................................................................................... 1 2 Power System and Operating Reserves Overview ................................................................................ 4 2.1 Regulating Reserves .................................................................................................................... 12 2.2 Following Reserves ..................................................................................................................... 18 2.3 Contingency Reserves ................................................................................................................. 20 2.4 Ramping Reserves ...................................................................................................................... 22 2.5 Primary Reserves (Under Contingency Reserves) ...................................................................... 24 2.6 Secondary Reserves (Under Contingency Reserves and Ramping Reserves) ............................ 28 2.7 Tertiary Reserves (Under Contingency Reserves and Ramping Reserves) ................................ 28 3 Operating Reserves in Practice ........................................................................................................... 29 3.1 North America (NERC) .............................................................................................................. 29 3.1.1 Regulating Reserves ............................................................................................................ 32 3.1.2 Following Reserves ............................................................................................................. 36 3.1.3 Contingency Reserves ......................................................................................................... 36 3.1.4 Ramping Reserves............................................................................................................... 38 3.1.5 Primary Reserves ................................................................................................................ 38 3.1.6 Secondary Reserves ............................................................................................................ 38 3.1.7 Tertiary Reserves ................................................................................................................ 39 3.2 Key North American Regional Differences ................................................................................ 40 3.2.1 Regulating Reserves ............................................................................................................ 40 3.2.2 Following Reserve .............................................................................................................. 45 3.2.3 Contingency Reserve .......................................................................................................... 45 3.2.4 Ramping Reserve ................................................................................................................ 46 3.2.5 Primary Reserve .................................................................................................................. 46 3.2.6 Secondary Reserves ............................................................................................................ 49 3.2.7 Tertiary Reserves ................................................................................................................ 49 3.3 Europe: ENTSO-E (UCTE) ........................................................................................................ 50 iii 3.3.1 Regulating Reserves ............................................................................................................ 50 3.3.2 Following Reserves ............................................................................................................. 52 3.3.3 Contingency Reserves ......................................................................................................... 52 3.3.4 Ramping Reserves............................................................................................................... 54 3.3.5 Primary Reserves ................................................................................................................ 54 3.3.6 Secondary Reserves ............................................................................................................ 55 3.3.7 Tertiary Reserves ................................................................................................................ 56 3.4 Summary ..................................................................................................................................... 57 4 New Proposed Methodologies and Renewable Integration Studies.................................................... 60 4.1 Large-Scale Renewable Integration Studies ............................................................................... 60 4.2 Academic Research ..................................................................................................................... 78 4.3 Summary ..................................................................................................................................... 85 5 Conclusions and Discussion................................................................................................................ 87 6 References ........................................................................................................................................... 89 iv List of Figures Figure 1: Example of Variability and Uncertainty. ....................................................................................... 2 Figure 2: Power system operation time frames. ...........................................................................................