Wind Energy Systems Integration
Goal
The goal of the Systems Integration activity is: "By 2012, complete program activities addressing electric power market rules, interconnection impacts, operating strategies, and system planning needed for wind energy to compete without disadvantage to serve the Nation's energy needs."
A Fair Playing Field for Wind Energy
As the need to stabilize the nation's energy resources and electricity demands increase, more utilities are seriously evaluating wind power to provide a portion of their generation mix. At the same time, many utilities are expressing concerns about possible impacts on system operations when greater percentages of wind power are introduced into the electric power system. Their concerns, if not adequately addressed, could limit the development potential of wind power in this country.
Wind energy researchers are assisting industry partners with a number of projects aimed at increasing utility understanding of integration issues and confidence in the reliability of new wind turbine products. Information and tools gained from the projects will be distributed through a national outreach effort to investor-owned utilities, electric cooperatives, public power organizations, and energy regulators to encourage the inclusion of wind power in generation portfolios and ensure the continued growth of the wind energy industry.
The Systems Integration strategy is to assist regional electric system planning and operations personnel to make informed decisions about the integration of wind energy into their systems. Six primary targets have been identified:
- Technology Characterization and Data Collection
- Tools and Methods Development
- Application and Implementation
- Integration of Wind Energy and Hydropower Technologies
- Wind Energy and Hydrogen Production
- Wind Energy and Clean Water
Technology Characterization and Data Collection
Wind Generator Modeling
The program is working with the wind industry to provide utilities and grid operation organizations that evaluate interconnection and system impacts of proposed wind farms with better wind generator electrical models. Without better wind generator models, the grid evaluations will use generic induction generator parameters. By using non-wind-specific models, these organizations will not capture the advantages of variable-speed power electronics, including their ability to provide VARs and their fault ride-through capability. Without these better models, the amounts of wind capacity that will be allowed access to transmission interconnection because of concerns about system impact will be unnecessarily low.
Wind Farm Data Monitoring
The principal concern of electric utilities unfamiliar with wind energy is that the plant output can suddenly fall to zero. The second-by-second power fluctuations from commercial wind farms are not generally known, although data are becoming available through cooperative efforts between the program and industry. Without long-term data sets from various wind resource regimes, evaluation of the grid impacts of variability cannot be performed. The data gathering effort has recently been expanded significantly to include not only Minnesota and Iowa, but also plants in Texas, the Northwest, and California. Over the coming years, other locations in Colorado, Wyoming, and other states will be included.
Resource Characterization
The program will work to provide representations of the wind resource, including seasonal, daily and hourly data, where possible, to allow models to better characterize the potential benefits and impacts that wind can have on system operation and to assess availability of transmission.
Tools and Methods Development
Grid Operational Impact Analysis
The wind program will address the variable, normally uncontrollable nature of wind power plant output, and the additional needs that its operation imposes on the overall grid. At present, the generation and transmission operational impacts that occur due to wind variability are not well quantified. This research will include efforts to quantify and fairly allocate impacts in both an engineering and cost sense. Methods of analysis are at an early stage of development. Without realistic analysis and cost allocation, utilities tend to overestimate imposed operational costs, resulting in the undervaluing of wind power in the system. Unrealistically high ancillary cost evaluations will result in lower wind deployment rates.
Transmission and Generation Planning
Continued growth in electric loads results in the need to plan for and install new generators and transmission lines. Wind generation is a relatively new power source in the evolving competitive wholesale electric markets, so existing planning organizations and methods do not generally include wind as an option. Future utility resource plans and regional planning efforts need to include wind stakeholders in the overall process. Characterizations of potential wind resource locations and power delivery profiles are critical to accurate assessment of potential transmission line upgrades or expansions. In addition, the reliability characteristics (capacity credit) resulting from wind and utility load temporal profile matches have an impact on the valuation of wind from the planning perspective. Most of the foregoing can be handled by existing utility practices, as long as the required data are known.
The problem at the moment for wind developers is that existing practice for interconnection requires the same level of interconnection studies for a 25 MW wind plant as for a 1000 MW coal-steam plant and as each study is completed the dynamics of the network often change, rendering an earlier study invalid. This is an expensive, time-consuming hurdle for most wind projects. What is needed in each region for cost-effective deployment of wind power is an integrated study such as the AWEA study of 10,000 MW of wind that was recently completed. The role of the wind program is to provide the technical information required and to provide assistance where needed.
Application and Implementation
Grid Rules Development
As a low capacity factor, variable resource, often located far from load, deployment of wind energy is impacted by the FERC-driven transmission organizational restructuring processes, which are setting the stage for grid treatment of wind power into the future. Wind energy information and interests must be at the table in each region for both interim and future rule development processes. This is a major challenge for the entire wind energy community. The methods developed in other tasks must be presented and applied to specific grid rule development processes in these venues.
Operational Impacts Mitigation Strategies
As wind deployment expands into the future, costs for grid integration of wind may increase, especially with higher penetrations. Both short- and longer-term mitigation of intermittency issues, including wind plant forecasting and control, application of energy storage and regional cooperation, could reduce additional integration costs.
Integration of Wind Energy and Hydropower Technologies
While fluctuating power levels and transmission constraints have hampered ready adoption of wind energy to the utility grids, fluctuating water levels, growing pressures on water supplies, the need for flood controls, and environmental issues are just a few of the constraints that may limit the future growth of hydroelectric production. DOE has started a research project to examine whether wind and hydropower technologies can work together to provide a stable supply of electricity to an interconnected grid. While researchers theorize that hydropower facilities may be able to act as a "battery" for wind power by storing water during high-wind periods, a detailed analysis examining regulation, load following, reserve, and generator and grid operations has not been performed.
To gain a better understanding of the synergy that may exist between wind and hydropower technologies, DOE researchers are working with federal agencies such as the Bonneville Power Administration, the Western Area Power Administration, and the Tennessee Valley Authority to analyze potential and existing generation projects and watershed basin and electric control areas. One of the key questions they will try to answer is: Can hydro operations be modified to accommodate wind without adversely affecting the other flow requirements? They will also attempt to quantify the benefits of integrating wind and hydropower systems.
Wind Energy and Hydrogen Production
Wind energy can be harnessed to provide electricity at some of the lowest costs available for new generation. Coupling wind turbines to hydrogen-generating electrolyzers has the potential to provide low-cost, environmentally friendly distributed generation of hydrogen in addition to electricity. In this way, hydrogen generation can be a pathway for wind generation to contribute directly to reducing the nation's reliance on imported fuels.
DOE researchers are investigating key technical and market issues in an effort to explore this wind and hydrogen synergy, specifically:
- What regions of the United States have the greatest potential for employing wind turbines to produce both electricity and hydrogen, and under what conditions and time frame are they likely to become economical?
- What are the costs of wind systems that produce both electricity and hydrogen, both today and in the future?
- What are the opportunities for reducing system cost, by designing hybrid wind-based systems specifically for production of electricity and hydrogen?
- What areas should research focus on to have the greatest impacts on cost, both in the near- and long-term?
DOE wind researchers are developing a modeling framework to identify promising development areas and better define costs, to provide a systematic summary for the potential for co-producing hydrogen fuel and electricity.
Wind Energy and Clean Water
Wind generation enhances the value of our national water resources. By using this abundant and competitive homeland energy resource today, we can enhance regional water stocks and secure future water resources.
Wind power can alleviate demand for water by traditional generation sources and contribute toward resolving conflicts surrounding freshwater uses. Irrigation is the largest user of freshwater in the United States. Thermal electric power plants are the second largest users of freshwater in the United States. The number of power plant permit denials due to high water resource demands is rising.
Wind applications could include energy for desalination, water treatment from oil and gas exploration processes, power for municipal wastewater treatment, and water pumping for irrigation. Wind can benefit a wide range of stakeholders across the country, including large water users, coastal and western areas, and the public sector.