During the past few years, there has been significant interest in alternative ways to manage power systems over a larger effective electrical footprint. Large regional transmission organizations in the Eastern Interconnection have effectively consolidated balancing areas, achieving significant economies of scale that result in a reduction in required reserves. Conversely, in the WesternInterconnection there are many balancing areas, which will result in challenges if there is significant wind and solar energy development in the region. A recent proposal to the Western Electricity Coordinating Council suggests a regional energy imbalance service (EIS). To evaluate this EIS, a number of analyses are in process or are planned. This paper describes one part of an analysis of theEIS's implication on operating reserves under several alternative scenarios of the market footprint and participation. We improve on the operating reserves method utilized in the Eastern Wind Integration and Transmission Study and apply this modified approach to data from the Western Wind and Solar Integration Study.

The anticipated increase in variable generation in the Western Interconnection (WI) over the next several years has raised concerns about how to maintain system balance, especially in smaller Balancing Areas (BAs). Given renewable portfolio standards in the West, it is possible that more than 50 gigawatts (GW) of wind capacity will be installed by 2020. Significant quantities of solar generation are likely to be added as well. The consequent increase in variability and uncertainty that must be managed by the conventional generation fleet and responsive load make it attractive to consider ways in which Balancing Area Authorities (BAAs) can pool their variability and response resources, thus taking advantage of geographic and temporal diversity to increase overall operational efficiency. Our analysis considers several alternative forms of an Energy Imbalance Market (EIM) that have been proposed in the non-market areas of the WI. The proposed EIM includes two changes in operating practices that independently reduce variability and increase access to responsive resources: BAA cooperation and sub-hourly dispatch. As proposed, the EIM does not consider any form of coordinated unit commitment; however, over time it is possible that BAAs would develop formal or informal coordination plans. This report examines the benefits of several possible EIM implementations, both separately and in concert.

The anticipated increase in variable generation in the Western Interconnection over the next several years has raised concerns about how to maintain system balance, especially in smaller Balancing Authority Areas (BAAs). Given renewable portfolio standards in the West, it is possible that more than 50 gigawatts of wind capacity will be installed by 2020. Significant quantities of solar generation are likely to be added as well. The consequent increase in variability and uncertainty that must be managed by the conventional generation fleet and responsive loads has resulted in a proposal for an Energy Imbalance Market (EIM). This paper extends prior work to estimate the reserve requirements for regulation, spinning, and non-spinning reserves with and without the EIM. We also discuss alternative approaches to allocating reserve requirements and show that some apparently attractive allocation methods have undesired consequences.

This analysis indicates the extent to which pooled regional dispatch for matching generation to load mitigates the costs and improves associated reliability, particularly in scenarios with high penetration of variable output resources, such as wind.

5.3 Simulation scenario based on 195 MW of positive power reserve -- 5.4 Simulation scenario based on 265 MW of positive power reserve -- 5.5 Potential power reserve provision with wind power in Germany during 2009 -- 5.6 Summary chapter 5 -- 6. Capability of wind farm clusters to provide power reserve -- 6.1 Project "Integration großer Offshore-Windparks in elektrische Versorgungssysteme"--6.1.1 Project description and main objectives -- 6.1.2 Project partners -- 6.1.3 Test scenario -- 6.1.4 Positive power reserve tests in the wind farm cluster"Bertikow" -- 6.1.5 Results of the project -- 6.2 Project "Wind on the Grid" -- 6.2.1 Project description and main objectives -- 6.2.2 Project partners -- 6.2.3 Control strategies development -- 6.2.4 Test scenario in Portugal (REN) -- 6.2.5 Electrical characteristics of the tested wind farm clusters -- 6.2.6 Description of the active power limitation tests in Portugal -- 6.2.7 Analysis of active power control tests in Portugal -- 6.2.8 Results of the project -- 6.3 Summary of chapter 6 -- 7. Conclusions and recommendations for further research -- 7.1 Conclusions -- 7.2 Recommendations for further research -- 8. Acknowledgments -- Appendix -- Appendix I: Project support for the thesis -- Appendix II: Wind Farm Cluster Management System (WCMS) -- Appendix III: Pre-qualification rules for wind farms -- Appendix IV: Economical consideration of providing power reserve with wind power -- Appendix V: References -- List of tables -- List of equations -- List of references -- List of Acronyms and Abbreviations -- Back cover

The variability that wind adds to the system requires the activation or deactivation of additional operating reserves. This paper provides a high-level international comparison of methods and key results from both operating practice and integration analysis, based on the work in International Energy Agency IEA WIND Task 25 on Large-scale Wind Integration. The paper concludes with an assessment of the common themes and important differences, along with recent emerging trends.