Wind Turbine Cascade Controller for Load Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wind turbine control systems fail to effectively reduce loads on critical components such as the tower and rotor blades, particularly during variations in wind speed, leading to potential damage and inefficiencies in power output.
Innovation Solution
A cascade control structure is implemented, where a fast inner control loop compensates for the slower outer loop, using rotor acceleration performance as an input signal to adjust pitch rates and limit setpoints, thereby reducing excessive loads and optimizing power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional single-loop speed controller is used, then the control system is simple, but the response speed is slow and cannot effectively reduce loads on components
Solution Approach 1:
The control system is segmented into two independent loops: an outer speed control loop and an inner acceleration control loop. Each loop handles specific control functions, with the outer loop managing overall speed regulation and the inner loop handling rapid acceleration changes. This segmentation enables faster response without excessive complexity.
Solution Approach 2:
The inner control loop is nested within the outer control loop, where the outer loop's speed setpoint becomes the inner loop's reference. This nested structure allows the fast inner loop to operate within the framework of the slower outer loop, achieving rapid response while maintaining overall control stability.
2Speed
If the controller increases the pitch rate rapidly to reduce speed, then the speed regulation is faster, but excessive loads are imposed on the rotor and tower
Solution Approach 1:
The inner control loop continuously monitors actual rotor acceleration and compares it with the desired acceleration derived from the speed setpoint. This feedback mechanism allows the controller to adjust pitch rates dynamically, achieving fast speed regulation while preventing excessive loads by correcting over-acceleration in real-time.
Solution Approach 2:
The controller dynamically adjusts the pitch rate setpoint based on real-time conditions rather than using fixed rates. The inner loop modifies the pitch rate continuously to match the actual acceleration needs, enabling optimal speed control while minimizing mechanical loads on the rotor and tower structure.
3Productivity
If the controller allows large speed changes, then the power output can be optimized, but the cutting loads on components increase
Solution Approach 1:
The inner control loop applies partial correction actions rather than allowing full excessive acceleration. By continuously monitoring and adjusting the pitch rate based on actual acceleration feedback, the system achieves optimal power output through controlled acceleration while preventing excessive loads that would compromise component strength.
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to a controller structure (300) for a wind turbine (100) comprising an aerodynamic rotor (106) having at least one rotor blade (108). The controller structure (300) is designed to control a rotational speed (n) of the rotor (106) of the wind turbine (100), wherein the controller structure (300) is designed as a cascade control and has an outer control loop (310) and an inner control loop (350), wherein the inner loop (350) receives an input signal (340) which includes a change of speed, a speed acceleration, a function of the change of speed and/or a function of the speed acceleration.