Wind Turbine Power Coefficient Calibration via Perturbation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wind turbines face sub-optimal operations due to mismatches between predetermined and actual power coefficients, leading to incorrect pitch and tip-speed-ratio setpoints.
Innovation Solution
A method for controlling wind turbines in partial load operation mode using a tip-speed ratio (TSR) tracking scheme, where the operating power coefficient is adjusted through an adjustment process involving a scaled power coefficient and a transfer function from a perturbation signal to a power error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a predetermined power coefficient is used in the control scheme, then the control system is simple to implement, but the operational efficiency deteriorates due to mismatch between predetermined and actual power coefficients
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the actual power coefficient by comparing measured rotor power with estimated rotor power, and adjusts the operating power coefficient accordingly. This closed-loop feedback system resolves the contradiction by maintaining operational efficiency through continuous adaptation while keeping the control system relatively simple.
Solution Approach 2:
The patent applies preliminary action by adding a time-varying perturbation signal to the power setpoint before evaluating the transfer function. This pre-adjustment allows the system to proactively calibrate the power coefficient based on predicted performance rather than reacting to errors after they occur, improving operational efficiency without significantly increasing control complexity.
2Measurement precision
If wind speed measurements are used to determine operating conditions, then the accuracy of power coefficient determination improves, but the device complexity and measurement requirements increase
Solution Approach 1:
The patent introduces an intermediary approach by using a wind speed estimator based on power or torque balance between aerodynamic and electrical components, rather than direct wind speed measurements. This intermediary estimation method achieves sufficient accuracy for power coefficient determination while avoiding the complexity of direct wind speed measurement systems, especially given that anemometer measurements are already disturbed by the rotating rotor.
3Ease of operation
If the operating power coefficient is not adjusted to match actual conditions, then the control scheme remains simple, but wrong pitch and tip-speed-ratio setpoints are selected leading to sub-optimal operations
Solution Approach 1:
The patent implements self-service by enabling the control system to automatically determine and adjust its own operating power coefficient without external intervention. The controller uses the transfer function evaluation and frequency response analysis to self-calibrate, ensuring optimal pitch and tip-speed-ratio setpoints while maintaining ease of operation through automated adaptation rather than complex manual tuning.
4Productivity
If a transfer function evaluation with perturbation signals is implemented to calibrate the power coefficient, then the operational efficiency improves, but the control process complexity increases
Solution Approach 1:
The patent applies periodic action by using a time-varying perturbation signal with specific frequency characteristics to evaluate the transfer function. This periodic excitation allows the system to efficiently extract the necessary information for power coefficient calibration through frequency response evaluation, achieving improved operational efficiency while managing control process complexity through structured periodic testing rather than continuous complex adjustments.
Data Source
Figure 1~2
Figure 3~7
Figure 5~6
AI summary
The present invention relates to controlling a wind turbine with a scaled power coefficient where the scaled power coefficient is determined in an adjustment process. In particular is disclosed control of a wind turbine in a partial load operation mode based on a tip-speed ratio (TSR) tracking scheme which based on an estimated wind speed determines a power setpoint. The disclosed adjustment process comprises setting a scaled power coefficient as a predetermined power coefficient multiplied by a scaling factor; adding a time-varying perturbation signal to the power setpoint; determining a transfer function from the perturbation signal to a power error; evaluate the frequency response of the transfer function over a time period to determine the scaling factor which minimizes the gain of the transfer function; and setting the operating power coefficient as the scaled power coefficient.