Wind Turbine Control Hysteresis Avoids Resonance
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Solution Overview
Problem
Wind turbines experience vibrations due to resonance frequencies, leading to efficiency losses when trying to avoid critical speed ranges, especially when wind speeds align with these frequencies, causing frequent switching between speed ranges and resulting in performance loss.
Innovation Solution
A method for controlling wind turbines using a speed/power characteristic curve with a hysteresis range that adjusts rotor speed and power output to maintain stability and efficiency, allowing the turbine to operate above or below critical speeds without entering resonance frequencies, utilizing a hysteresis section structure with distinct power or torque adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the wind turbine rapidly traverses the critical speed range by increasing rotational speed, then the resonance problem is avoided, but power loss occurs due to delayed power output increase
Solution Approach 1:
The patent applies dynamics by making the speed-power characteristic curve adaptive and variable rather than fixed. The curve dynamically adjusts its shape based on operating conditions, allowing the control system to optimize the trade-off between rapidly traversing critical speeds and maintaining power output. This is achieved by modifying the functional relationship between speed and power setpoint in real-time.
Solution Approach 2:
The patent changes the parameters of the speed-power characteristic curve, specifically introducing a hysteresis range around critical speeds. Instead of a single-valued function, the system uses a range of acceptable speeds for each power level, or vice versa. This parameter modification allows the turbine to operate within a band of speeds rather than following a precise trajectory, enabling faster traversal of critical regions.
2Ease of operation
If the wind turbine operates with a fixed speed-power curve, then control simplicity is maintained, but efficiency is reduced when wind speed aligns with critical rotational speeds
Solution Approach 1:
The patent segments the speed-power characteristic curve into multiple regions or modes, including normal operation mode and hysteresis mode. By dividing the control strategy into distinct segments based on operating conditions (particularly proximity to critical speeds), the system can apply different control characteristics appropriate to each region while maintaining an overall simple control architecture.
Solution Approach 2:
The control system transitions from a static fixed curve to a dynamic adaptive curve that can change its characteristics based on the operating point. The speed-power relationship becomes a time-varying function that adapts to avoid critical speeds while maintaining efficiency, achieved through real-time modification of the characteristic curve parameters.
Data Source
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AI summary
The invention relates to a method for controlling a wind energy installation (100) having an aerodynamic rotor with rotor blades, the blade angle of which can be adjusted, comprising the steps of operating the wind energy installation in a partial load range with a rotor speed below a nominal speed and with an output power below a nominal power, using a speed/power characteristic curve which indicates a relationship between a rotor speed established on the basis of the prevailing wind and an output power to be set for this purpose or using a speed/torque characteristic curve which indicates a relationship between a rotor speed established on the basis of the prevailing wind and a torque to be set for this purpose, setting an output power according to the speed/power characteristic curve or a torque according to the speed/torque characteristic curve, wherein the speed/power characteristic curve or the speed/torque characteristic curve has a hysteresis region in the region of a problem speed to be avoided.