Wind Turbine Rotor Speed Control for Tower Load Damping
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Solution Overview
Problem
Wind turbines experience increased loads on their towers due to oscillations caused by varying rotor speeds during wind gusts, leading to potential damage and reduced energy production when trying to maintain constant power output.
Innovation Solution
A control method that adjusts the pitch angle and generator torque of wind turbine rotor blades based on actual rotor speed, using a combination of main and additional power or torque set values to manage rotor speed deviations and reduce oscillatory loads, while maintaining energy production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the generator torque is adjusted to keep output power constant during wind gusts, then the power output is maintained, but the rotor speed variations increase causing oscillating loads on the tower
Solution Approach 1:
The control system dynamically adjusts the generator torque based on the actual rotor speed deviation from the reference speed. Instead of maintaining constant power, the torque is varied in response to wind gusts to actively dampen rotor speed oscillations, thereby reducing tower loads while accepting some power variation
Solution Approach 2:
The control method uses feedback from the actual rotor speed measurement to continuously adjust the generator torque. The controller compares the actual rotor speed with the reference speed and modifies the torque accordingly to minimize speed deviations and reduce oscillating loads on the tower structure
2Force
If the rotor speed is allowed to vary significantly to reduce generator torque adjustments, then tower oscillating loads are reduced, but the energy production decreases
Solution Approach 1:
The control system applies partial action by only adjusting the generator torque when rotor speed deviations occur, rather than maintaining constant torque or power. This selective adjustment reduces tower loads during wind gusts while minimizing the impact on overall energy production by allowing normal operation during steady wind conditions
3Speed
If the pitch angle is adjusted frequently to control rotor speed, then the rotor speed stability is improved, but the mechanical wear and complexity of the pitch system increases
Solution Approach 1:
The generator torque acts as an intermediary control mechanism to manage rotor speed variations. By using the generator torque as the primary control variable rather than directly adjusting the pitch angle, the system achieves rotor speed stability while reducing the frequency and magnitude of pitch adjustments, thereby lowering mechanical wear and operational complexity
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 tower loads and increases energy production by stabilizing rotor speed and torque, allowing for more efficient operation during wind gusts without compromising power output.
Implementation Method 1
Each rotor blade has an adjustable pitch angle for adjusting an angle of attack between the rotor blade and the wind moving the rotor blade
Data Source
AI summary
Method for controlling a rotor speed of a rotor of a wind turbine at rated or curtailed operation conditions the rotor being an aerodynamic rotor having one or a plurality of rotor blades, and the wind turbine further having a tower and a generator wherein a pitch control provides a pitch angle set value depending on an actual rotor speed for setting a pitch angle of the rotor blades, a main control provides a main power or torque set value for controlling the power or torque of the generator, and an additional control provides an additional power or torque set value depending on the actual rotor speed, wherein the additional power or torque set value is provided as an offset value and is added to the main power or torque set value respectively, wherein the additional power or torque set value is calculated depending on a control deviation of the rotor speed, and optionally, in combination with the additional control, or instead of it, a maximum power control provides a maximum power value as a varying value for limiting an output power of the generator and the maximum power value is calculated depending on a predetermined power limit value, and depending on a predetermined reference duration, in order to provide for the reference duration an average power reaching or at least not exceeding the predetermined power limit value.