Fixed-Speed Wind Turbine Blade Angle Control
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Solution Overview
Problem
Fixed-speed wind turbines face limitations in output and high costs due to their design, which is based on outdated principles that prioritize blade length over angle of attack and rotational speed, leading to inefficiencies at low wind speeds and high energy consumption from the grid.
Innovation Solution
A method to determine and control the optimal angle of attack for fixed-speed wind turbine blades, considering them as obstructions to airflow, using a truss-supported structure with flat blade segments, and adjusting angles based on wind speed to maximize energy extraction at low and medium wind speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fixed-speed wind turbine blades are designed with aerodynamic airfoils based on Betz' equation, then the swept area is increased to maximize power output, but the angle of attack cannot be adjusted at wind speeds below rated speed, leading to excessive energy consumption and potential grid shutdown
Solution Approach 1:
The patent applies the dynamics principle by making the blade angle adjustable through rotation around the longitudinal axis. The blade can dynamically change its attack angle from a fixed aerodynamic configuration to an adjusted position, enabling adaptation to different wind speed conditions. This dynamic adjustment allows the fixed-speed turbine to optimize performance across varying wind speeds rather than being locked into a single operating point
Solution Approach 2:
The patent implements parameter changes by modifying the blade's operational parameters - specifically the attack angle - in response to changing wind conditions. By rotating the blade around its longitudinal axis, the system changes the geometric parameter of the blade's orientation relative to the wind, thereby adapting the power extraction characteristics to match current wind speed conditions
2Adaptability or versatility
If the blade angle is rotated 2 to 10 degrees on its longitudinal axis, then some adaptability is achieved, but there are no rules for adjusting the attack angle, resulting in turbines falling short of economic and technological indicators
Solution Approach 1:
The patent applies feedback by establishing a control system that monitors wind speed conditions and automatically adjusts the blade attack angle accordingly. The adjustment rules provide feedback-based control where the blade position is continuously optimized based on real-time wind conditions, ensuring maximum energy extraction efficiency across the operating range
Solution Approach 2:
The patent implements preliminary action by pre-establishing adjustment rules that determine the optimal blade angle for different wind speed ranges. These predetermined rules enable the system to proactively adjust to changing conditions rather than reacting after performance degradation occurs
3Power
If turbine blades are designed with aerodynamic airfoils supporting blade movement, then power output is maximized at rated wind speed, but the design overlooks other important physical factors such as angle of attack and rotational speed, leading to inefficiencies at low wind speeds
Solution Approach 1:
The patent applies dynamics by transitioning from a static aerodynamic airfoil design to a dynamic configuration where the blade can rotate around its longitudinal axis. This dynamic capability allows the blade to adjust its effective angle of attack in response to varying wind speeds, optimizing energy extraction at both low and rated wind speeds rather than being optimized only for rated conditions
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 enables fixed-speed wind turbines to achieve optimal output at low and medium wind speeds, reducing costs and allowing for efficient operation and restart, while maintaining high output at high wind speeds without significantly impacting the grid.
Implementation Method 1
the wind turbine blade as an obstruction of the airflow... the blade surface of a very short blade segment should be considered flat... wind turbine blades have been broadly viewed as objects flying in the wind
Data Source
Figure 1
AI summary
The invention details a method of determining and controlling the attack angle of fixed-speed wind turbine blade aiming at finding out an appropriate angle of attack for optimal extraction of wind energy at low to medium wind speed, which comprises three steps: step 1 - defining basic parameters of the turbine including the blade length and width, fixed rotational speed, rated wind speed, start-up speed and the lowest speed at which the turbine is forced to stop, and the relationship with the wasted power; step 2 - defining wind speed based on which a set of attack angles can be calculated to form an overall optimal attack angle of the wind turbine blade; step 3 - calculate necessary physical parameters to come up with the most effective method of controlling the turbine blade; this invention is applicable to the manufacture of fixed speed wind turbine that can be directly connected to the grid, making wind power costs as low as those of other conventional energy sources.