Over the last few decades, wind energy has evolved into a large international industry involving major players in the manufacturing, construction, and utility sectors. Significant innovation in the technology has resulted in larger turbines and wind plants with lower associated costs of energy. However, the increasing importance of wind energy’s role within the electricity sector imposes more requirements on the technology in terms of performance, reliability, and cost.
To address these changing expectations, the industry has made efforts that focus on achieving a variety of goals including reducing installed capital costs for the turbine and plant, decreasing the downstream costs for operation and maintenance (O&M), increasing energy production, and minimizing negative external environmental impacts such as noise emission or habitat disruption. In many cases, these goals involve trade-offs. For example, up-front investment in a robust component design may avoid large downstream costs for component repair and replacement. In another case, the design of a machine with a higher tip speed can reduce required torque and loads through the drivetrain, but at the same time these higher tip speeds can lead to more aero-acoustic noise that adversely impacts surrounding communities. Trade-offs, and techno-economical conflicts such as these exist throughout the entire system.
Considering the plant as a collection of wind turbines, the operation of the wind turbines and design of a wind plant is linked via:
- the atmosphere, where the operation of upwind turbines modifies the downstream flow locally, with a velocity deficit and added turbulence behind each rotor; and globally, acting as an additional surface drag on the atmospheric boundary layer;
- the electric system, where the voltage and frequency at one wind turbine may be a function of the power output of other wind turbines; and,
- plant control actions, where the logic used to distribute a power set-point to a given wind turbine may be a function of the operating conditions of other wind turbines.
Thus, understanding the design and dynamics of a wind power plant requires a system-level model. There are open research topics in all areas of wind power plant design and operation. For instance, how does pitching the blades of a group of upstream turbines affect the atmospheric boundary layer flow at a group of downstream turbines, where the convection time at the nominal hub-height wind speed may be a half-hour or more? How should the power dispatch function respond to rapidly varying flow conditions across the plant, for instance with the passage of weather fronts or thunderstorms? How should the converters at each turbine -- and for plants with HVDC transmission, at each end of the HVDC line -- be operated to best support power-system stability? How should the level of fatigue degradation of each turbine be monitored, and how should the turbines be operated, in order to most economically distribute the degradation among the turbines in the plant? What influence does turbine placement have on energy production, effective turbulence intensity, fatigue degradation, maintenance requirements, and system costs?
Finding answers to these and many more system-level questions is a multi-disciplinary effort, requiring the coordination of diverse research groups and analytical capabilities. To fully assess how a change in a design parameter affects the myriad of objectives in system performance and cost, a holistic and integrated approach is needed. Integrated system research, design and development (RD&D) can provide opportunities for improvements in overall system performance and reductions in overall cost of energy.
The mission of this task is to improve the practice and application of systems engineering to wind energy RD&D. This will be achieved through a set of coordinated international research activities that move the community towards the analysis of wind power plants as holistic systems.
- Improve quality of systems engineering by practitioners through development of best practices and benchmarking exercises
- Promote general knowledge and value demonstrations of systems engineering tools and methods applied to wind energy RD&D
Expected results of the effort will include guidelines to support integration of analytical capabilities for modeling wind turbine and plants, reference wind turbine and plant models that may be used by the entire wind energy RD&D community, and reports on best practices in performing MDAO analysis of wind turbines and plants.