Dynamic Wind Turbine Shutdown via Rotor Speed Feedback
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Solution Overview
Problem
Existing wind turbine shutdown methods fail to effectively manage excessive loads on components during shutdown, particularly in extreme wind conditions, leading to potential structural failure and reduced component lifespan.
Innovation Solution
A dynamic control method that adjusts blade pitch based on real-time rotor speed and tower movement, using a closed-loop feedback system to maintain optimal rotor speed and reduce loading on the drivetrain and gearbox, while accounting for fore-aft movement and wind direction to minimize stress on the turbine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wind turbine blades are pitched out at a predetermined pitch change speed to reduce power output, then the shutdown procedure is simple and fast, but excessive loads are induced on the wind turbine components
Solution Approach 1:
The patent applies dynamics by transitioning from a static predetermined pitch change speed to a dynamic pitch change speed that adapts in real-time. The control system continuously adjusts the blade pitch rate based on measured rotor speed deviations and tower fore-aft movements, allowing the shutdown process to be both fast and load-sensitive. This resolves the contradiction by making the pitch speed flexible rather than fixed.
Solution Approach 2:
The patent implements feedback control by measuring actual rotor speed and tower fore-aft movement, comparing these to reference values, and using the errors to adjust the blade pitch rate. This closed-loop feedback mechanism ensures that the pitch speed automatically reduces when excessive loads or speed deviations occur, preventing component damage while maintaining shutdown efficiency.
2Loss of time
If the rotor speed is rapidly reduced to zero during shutdown, then the shutdown time is minimized, but extreme loading occurs on the drivetrain and gearbox
Solution Approach 1:
The patent applies preliminary action by establishing a dynamic pitch reference that proactively anticipates loading conditions. Before excessive loads can occur, the control system continuously adjusts the pitch rate based on real-time measurements, preventing extreme drivetrain loading while maintaining rapid shutdown. The fore-aft tower movement measurement provides early warning of potential loading issues.
Solution Approach 2:
The patent changes the parameter of pitch change speed from a fixed value to a dynamically adjusted value based on rotor speed error and tower movement. This parameter change allows the system to optimize the trade-off between shutdown speed and drivetrain loading, reducing pitch rate when loading becomes excessive and increasing it when safe to do so.
3Device complexity
If the blade pitch is controlled without considering tower fore-aft movement, then the control system is simpler, but the loading on the tower and foundation increases
Solution Approach 1:
The patent uses feedback control by measuring tower fore-aft movement and using this information to adjust the blade pitch rate. The measured fore-aft movement is fed into the control algorithm, which modifies the pitch command to reduce tower loading. This feedback mechanism adds complexity but is necessary to resolve the loading issue.
Solution Approach 2:
The control system acts as an intermediary between the shutdown command and the blade pitch actuation. It processes both rotor speed and tower fore-aft movement measurements, and uses this combined information to mediate the pitch rate, balancing the need for fast shutdown with the need to protect tower and foundation structures.
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 reduces extreme loading on wind turbine components during shutdown, enhancing safety and extending component lifespan by dynamically managing rotor speed and blade pitch, thereby improving the design and operational safety of wind turbines.
Implementation Method 1
The swept area dictates how much of a given air mass is intercepted by the wind turbine and, thus, influences the power output of the wind turbine and the forces and bending moments experienced by the components of the turbine during operation.
Implementation Method 2
converting the energy extracted from the wind by the rotating blades into electrical power output
Implementation Method 3
the wind turbine controller may cause the blade pitch angle to be increased (towards 90 degrees) using the blade pitch actuators. This is commonly known as pitching the blade out, which causes the power output to be reduced since the pitched blade acts as an aerodynamic brake.
Data Source
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AI summary
A method is provided for controlling the shutdown of a wind turbine of the type having a rotor, the rotor comprising one or more wind turbine blades. The method comprises dynamically determining a rotor speed reference; obtaining a measure of the rotor speed of the rotor; determining an error between the rotor speed reference and the rotor speed of the rotor; and controlling a pitch of one or more of the wind turbine blades based on the determined error. A corresponding wind turbine controller and a wind turbine including such a controller are also provided.