Wind Turbine Speed Control for Predictive Overspeed Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wind turbines experience overspeeding during rapid increases in wind speed, leading to shutdowns and mechanical stress, which existing speed control systems either fail to prevent effectively or cause excessive operating loads and oscillations.
Innovation Solution
A predictive speed control method that evaluates test criteria to anticipate overspeed, adjusting controller gain and control structure to prevent overspeed by implementing differential components, nonlinear control, and modifying blade angles based on blade angle deviations and extrapolated speed profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller gain is increased to prevent overspeeding during rapid wind speed increases, then the speed control effectiveness is improved, but the operating load and pitch angle oscillations increase excessively
Solution Approach 1:
The controller gain is made dynamically adjustable rather than fixed. The system switches between a first controller gain value for normal operation and a second, higher controller gain value when overspeed risk is detected. This dynamic adjustment allows the system to prevent overspeeding when necessary while maintaining normal operating loads during stable conditions.
Solution Approach 2:
The controller gain parameter is changed based on operating conditions. The system monitors rotor speed and wind speed to determine when to switch between different gain values. This parameter change enables the controller to be more aggressive (higher gain) only when needed for overspeed prevention, rather than continuously applying high gain that would cause excessive loading.
2Speed
If the controller gain is increased to counteract rapid speed increases, then the speed regulation response is improved, but pitch angle oscillations and rotor blade stress increase
Solution Approach 1:
The controller gain is dynamically adjusted based on the operational state. During normal operation with stable pitch angles, a lower gain maintains stability. When rapid wind speed increases are detected that could cause overspeeding, the system switches to a higher gain to provide stronger corrective action, accepting temporary increased activity only when necessary.
Solution Approach 2:
The system detects early signs of rapid wind speed increases and preemptively adjusts the controller gain before overspeeding occurs. By monitoring the rate of change of wind speed and rotor speed, the system can switch to high gain mode in advance, preventing the need for aggressive corrective actions that would cause oscillations.
3Reliability
If the speed control system applies strong deceleration to prevent overspeeding, then the rotor speed is regulated effectively, but mechanical stress on wind turbine parts increases
Solution Approach 1:
The controller gain parameter is adjusted to match the severity of the situation. During normal operation, low gain prevents unnecessary mechanical stress. When overspeed risk is detected, the gain is increased to provide stronger control action. This selective parameter change ensures strong deceleration is applied only when necessary for safety, rather than continuously applying strong control that would cause excessive mechanical stress.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a method for controlling a wind turbine (100) which has rotor blades (108) with adjustable blade angle and can be operated at a variable speed using a speed control system. The speed control system is configured to regulate the speed to a variable setpoint, comprising the steps of evaluating a test criterion to predict an impending overspeed, predicting an overspeed (nu) as a function of the at least one test criterion, and adjusting the speed control system when an overspeed (nu) has been predicted. A solution is proposed that avoids excessive increases in rotor speed even during strong increases in wind speed. In particular, reaching an overspeed that leads to shutdown is to be avoided without excessively increasing the operating loads.