Multi-rotor Wind Turbine Stability During Shutdown
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Solution Overview
Problem
Multi-rotor wind turbine systems face challenges in mechanical stability during shutdown, particularly due to gusts, which can lead to high loads and make shutdown unsafe or impossible, exceeding operational limits and design requirements.
Innovation Solution
A wind turbine system with a control system that applies a first control command to a subset of modules to reduce thrust force and a second control command to another subset to oppose thrust force changes, mitigating deflections and oscillations in the support structure, thereby stabilizing the system during shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-rotor wind turbine systems are implemented to improve transport and upscaling advantages, then productivity and flexibility are improved, but mechanical stability during shutdown deteriorates due to rotor interactions and gust-induced loads
Solution Approach 1:
The control system segments the shutdown process by dividing rotors into different groups (first subset and second subset) that are controlled independently. This allows staged shutdown where not all rotors terminate power production simultaneously, reducing abrupt thrust force changes and improving mechanical stability during the transition to shutdown state.
Solution Approach 2:
The control system applies preliminary counteracting thrust control to the second subset of rotors before and during the shutdown of the first subset. This preliminary anti-action opposes the thrust force changes occurring during shutdown, preventing excessive deflections and oscillations in the support structure that would otherwise occur with simultaneous rotor shutdown.
2Speed
If shutdown is performed during gusty wind conditions, then operational responsiveness is improved, but safety and design requirements are exceeded due to high loads and oscillations
Solution Approach 1:
The control system dynamically adjusts the shutdown process based on real-time wind conditions and rotor responses. During gusty conditions, the system modulates the shutdown sequence and thrust control forces to maintain stability, allowing shutdown to proceed safely even in previously prohibitive wind conditions by continuously adapting control parameters.
Solution Approach 2:
The control system continuously monitors thrust force changes, rotor positions, and support structure deflections during shutdown, using this feedback to adjust the shutdown sequence and thrust control in real-time. This closed-loop control enables safe shutdown during gusts by detecting adverse conditions and modifying the shutdown process to maintain operational limits.
3Device complexity
If all rotors are shut down simultaneously to simplify control, then device complexity is reduced, but mechanical stability deteriorates due to abrupt thrust force changes and support structure oscillations
Solution Approach 1:
The control system segments the rotor population into manageable subsets with distinct control commands, making the complex multi-rotor system controllable through modular control strategies. This segmentation transforms an intractable simultaneous control problem into a series of simpler, coordinated control actions that maintain stability.
Solution Approach 2:
The shutdown process employs periodic or sequential action by cycling through different rotor subsets in a controlled sequence rather than simultaneous termination. This staged approach distributes the thrust force changes over time, preventing abrupt load transitions that would cause excessive oscillations while maintaining manageable control 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 enhances stability and reduces high loads during shutdown in multi-rotor systems, enabling safe operation even in unstable wind conditions, and allows for cost-effective implementation with mature wind turbine technology.
Implementation Method 1
applying a second control command (2CC) to a second subset of wind turbine modules (2") positioned at a different position relative to the first subset of wind turbine modules (2'), the second control command enabling thrust control (TC) of the second subset of wind turbine modules (2") to oppose the said thrust force change
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
The invention relates to a wind turbine system (1) with a plurality of wind turbine modules each with a rotor (7). A control system is arranged to execute a shutdown procedure with a first control command (1CC) for terminating 5 power production from a first subset of wind turbine modules (2', M3, M4) resulting in a thrust force change with a reduced thrust force from the wind on a first part (3') of the support structure carrying the first subset of wind turbine modules (2'). A second control command (2CC) is applied to a second subset of wind turbine modules (2'', M1, M2) for enabling thrust control (TC) of 10 the second subset of wind turbine modules to oppose the thrust force change at the first part ('3). Thus, there is obtained an improved and cost-effective way of stabilizing a wind turbine system with multiple rotors during shutdown.