Wind Turbine Control via Passive Stall Elements
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Solution Overview
Problem
Conventional wind turbine control methods, such as peak-shaving control, reduce power output at wind speeds below the rated speed to mitigate aerodynamic loads, resulting in significant efficiency losses and limited control options for wind farms, especially since wind turbines often operate below their rated wind speed.
Innovation Solution
A system and method that determines the maximum power output of each wind turbine through loading analysis and adjusts operational setpoints to maximize power production without exceeding component load limits, allowing wind turbines to operate closer to their maximum power output across a range of wind speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If peak-shaving control method is used to reduce aerodynamic loads at rated wind speed by adjusting pitch angle towards feather, then blade loading is reduced, but power production is sacrificed and overall efficiency decreases
Solution Approach 1:
The patent changes the control parameter from pitch angle adjustment to active stall induction by modifying blade geometry. Instead of pitching blades towards feather to reduce loading, the system uses passive stall elements that create controlled flow separation, changing the aerodynamic characteristics without sacrificing power production at lower wind speeds
Solution Approach 2:
The patent divides the blade into different functional zones with passive stall elements positioned at specific locations. These segmented stall elements create localized flow separation that reduces peak loading while maintaining overall power production, allowing different parts of the blade to serve different functions
2Productivity
If pitch angle is maintained at power position to capture maximum energy, then power production is maximized, but aerodynamic loads continuously increase with wind speed creating peak loading at rated wind speed
Solution Approach 1:
The passive stall elements are pre-positioned on the blade to induce flow separation at specific Reynolds numbers. This preliminary geometric configuration ensures that when operating conditions reach certain wind speeds, the stall is automatically activated to reduce loading before peak loads are reached, preventing rather than reacting to the loading problem
Solution Approach 2:
The patent converts the harmful effect of flow separation (stall) into a beneficial control mechanism. Instead of trying to prevent stall, the system deliberately designs passive elements that create controlled stall conditions to reduce aerodynamic loads, turning what is normally considered an undesirable aerodynamic phenomenon into a useful load-management tool
3Stability of the object's composition
If wind turbines are constrained to operate at rated power output, then power output stability is maintained, but control options for wind farm are limited and total power output is reduced when operating below rated wind speed
Solution Approach 1:
The patent enables dynamic power output adjustment by allowing individual turbines to operate at variable power levels based on loading conditions. The passive stall mechanism provides natural load limiting that allows turbines to safely operate above or below rated power as needed, creating a dynamic system that can adapt to changing wind conditions and farm requirements rather than being constrained to fixed rated power operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly increases the total power output of a wind farm by eliminating operational constraints, ensuring the wind farm operates at or near its power output constraint, thereby enhancing efficiency and maximizing energy production.
Implementation Method 1
The rotor blades are the primary elements for converting wind energy into electrical energy. The blades typically have the cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between its sides. Consequently, a lift force, which is directed from the pressure side towards the suction side, acts on the blade.
Implementation Method 2
The lift force generates torque on the main rotor shaft, which is geared to a generator for producing electricity.
Data Source
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AI summary
A method 300 for controlling a wind farm 200 having a power output constraint is disclosed. The method 300 may include operating a plurality of wind turbines 202 within the wind farm 200. Each wind turbine 202 may include a baseline power output and a maximum power output 404. The baseline power output may be defined by a control-limited power curve as a function of wind speed 408. In addition, the method 300 may include comparing 304 a total power output for the wind farm 200 to the power output constraint of the wind farm 200, controlling the operation of at least one wind turbine 202 of the plurality of wind turbines 202 to provide an increased power output for the at least one wind turbine 202 when the total power output is less than the power output constraint.