Wind Turbine Pitch Control for Transient Wind Nulls
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Solution Overview
Problem
Wind power generator systems face output power fluctuations and efficiency reductions due to transient wind nulls, where a short-term reduction in wind speed causes the rotational speed of the windmill rotor to drop below rated levels, leading to reduced output power.
Innovation Solution
A wind power generator system that maintains output power at rated levels by adjusting the pitch angle of the blades, using a control method that switches between optimum curve control and rated value control based on rotational speed and pitch angle, ensuring effective energy extraction and stability during transient wind conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wind power generator system is designed to generate rated power when rotational speed is equal to or larger than rated rotational speed, then the system can operate efficiently under normal conditions, but output power is reduced below rated power when rotational speed drops below rated rotational speed due to transient wind null
Solution Approach 1:
The control system dynamically switches between two control modes (optimum curve control and rated value control) based on real-time rotational speed and pitch angle conditions. This dynamic adaptation allows the system to maintain rated power output during transient wind nulls by selecting the appropriate control mode, thereby resolving the contradiction between productivity and reliability.
Solution Approach 2:
The system changes control parameters (control mode selection) based on operating conditions (rotational speed and pitch angle). By transitioning between optimum curve control and rated value control modes, the system adjusts its behavior to maintain stable output power during transient wind nulls, addressing the reliability issue while preserving productivity.
2Reliability
If the pitch angle is increased to reduce wind energy extraction, then output power fluctuation is reduced, but generation efficiency is reduced
Solution Approach 1:
The system dynamically adjusts the pitch angle based on the detected control mode and rotational speed. During transient wind nulls in rated value control mode, the pitch angle is maintained at optimal values to preserve generation efficiency, while the control mode switching provides output power stability, thus resolving the contradiction between reliability and productivity.
Solution Approach 2:
The control system changes operational parameters (pitch angle and control mode) based on real-time conditions. By selectively applying rated value control with appropriate pitch angle adjustments only during transient wind nulls, the system maintains output power stability without significantly compromising generation efficiency under normal operating conditions.
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
The system effectively suppresses output power fluctuations and maintains generation efficiency by keeping output power at rated levels during transient wind nulls, utilizing rotational energy and maximizing energy extraction from the windmill rotor.
Implementation Method 1
the windmill rotor extracts more energy from wind when the pitch angle is small
Implementation Method 2
the torque of the generator is controlled with a field orientation control
Data Source
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AI summary
A wind power generator system according to the present invention includes: a windmill rotor including a blade having a variable pitch angle; a generator driven by the windmill rotor; and a control unit controlling the output power of the generator and the pitch angle of the blade in response to the rotational speed (ω) of the windmill rotor or the generator. The control unit performs a first control in which the output power is controlled in accordance with a predetermined power-rotational speed curve until the rotational speed (ω) is increased to reach a predetermined rated rotational speed, and performs a second control in which the output power is controlled to a predetermined rated power when the rotational speed (ω) exceeds the rated rotational speed; the control unit is responsive to the pitch angle for maintaining a state of performing the second control is or for switching to a state of performing the first control, when the rotational speed (ω) is reduced below the rated rotational speed after the control unit is once placed into the state of performing the second control. This provides a wind power generator system which suppresses output power fluctuation and generation efficiency reduction when a transient wind null occurs.