Wind Turbine Speed Control for Partial-Load Tip Speed Ratio
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Solution Overview
Problem
Conventional wind turbines experience reduced aerodynamic efficiency and performance in partial load operations due to operating away from optimal tip speed ratio, as they are limited by constant rated speed, which restricts their ability to maintain efficiency at higher wind speeds.
Innovation Solution
A method and system that dynamically vary the wind turbine's speed based on a non-monotonic torque-speed relationship, allowing the rotor speed to increase above the rated speed set point until system constraints are reached, and then decrease back to the rated speed, while calculating intermediate speed set points based on torque or power to optimize performance within electrical, mechanical, and thermal limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wind turbine operates at constant rated speed, then the system maintains stable electrical, mechanical, and thermal limits, but the aerodynamic efficiency is reduced due to operating away from optimal tip speed ratio
Solution Approach 1:
The patent implements dynamic speed adjustment by transitioning from a constant rated speed to a variable speed setpoint that increases with wind speed in the partial load region. The controller dynamically modifies the speed setpoint based on actual wind conditions, allowing the rotor to operate at optimal tip speed ratio while maintaining system reliability through controlled variation rather than arbitrary changes.
Solution Approach 2:
The patent changes the speed parameter from a fixed constant to a variable parameter that follows a defined trajectory. The speed setpoint is modified as a function of wind speed, creating a non-monotonic torque-speed relationship that optimizes aerodynamic performance while respecting system constraints. This parameter transformation enables the system to adapt to varying wind conditions.
2Productivity
If the rotor speed is increased to maintain optimal tip speed ratio at higher wind speeds, then the aerodynamic efficiency is improved, but the system reaches electrical, mechanical, and thermal constraints
Solution Approach 1:
The system dynamically adjusts the speed setpoint trajectory to increase speed in the partial load region while incorporating feedback mechanisms that monitor system constraints. When constraints are approached, the controller modifies the speed increase rate or direction, creating a dynamic balance between maintaining optimal aerodynamic performance and respecting system limitations.
Solution Approach 2:
The patent implements feedback control by continuously monitoring system constraints (electrical, mechanical, thermal parameters) and using this information to adjust the speed setpoint. The controller receives feedback on actual system state and modifies the torque-speed relationship accordingly, ensuring that the pursuit of optimal aerodynamic efficiency does not violate system constraints.
3Productivity
If the wind turbine uses a non-monotonic torque-speed relationship, then the operational space is expanded and power performance increases, but the control system complexity increases
Solution Approach 1:
The patent transforms the conventional monotonic torque-speed relationship into a non-monotonic one by introducing a variable speed setpoint that increases with wind speed. This parameter change creates additional operational space and improves power performance. The complexity is managed by implementing this transformation through the existing controller architecture, modifying control parameters rather than adding substantial hardware 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 the wind turbine's operational space, maintains optimal tip speed ratio at higher wind speeds, increases power performance, and improves stall margin for fouled or iced blades, thereby expanding the operational range and efficiency.
Implementation Method 1
The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy
Implementation Method 2
The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid
Data Source
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AI summary
A method 100 for operating a wind turbine 10 during partial load operation includes determining a power output of the wind turbine 10. The method 100 also includes determining 102 whether the power output is below a rated power of the wind turbine 10. If the power output is at the rated power, the method includes maintaining 106 a speed set point of the wind turbine 10 equal to a rated speed set point. However, if the power output is below the rated power, then the method includes varying, via a controller, the speed set point of the wind turbine 10 as a function of a torque of the wind turbine 10 in a non-monotonic torque-speed relationship.