Wind Turbine Generator Control for Torque Ripple and Noise Reduction
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Solution Overview
Problem
Wind turbines experience operational oscillations leading to increased sound emissions, which existing methods like geometric changes fail to effectively address across all operating points.
Innovation Solution
Implementing field-oriented closed-loop control for an active rectifier connected to the generator's stator, using d and q coordinates to modulate stator currents and account for rotor position, with additional 3-phase winding systems phase-shifted by 30° to reduce torque ripple and sound emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If geometric changes like skewing are made to the generator design, then cogging torques are counteracted at some working points, but the effect does not occur at all working points and the device complexity increases
Solution Approach 1:
The patent applies dynamics by making the skewing angle dynamic rather than fixed. The control unit calculates a skewing angle that varies with operating conditions (rotor speed, torque demand) and applies it through adjustable pitch elements, allowing the generator to adapt to different working points and maximize cogging torque counteraction across the entire operating range.
Solution Approach 2:
The patent changes the parameter of skewing angle from a fixed geometric value to a variable parameter that is continuously adjusted based on operating conditions. The control unit modifies the skewing angle parameter in response to changes in rotor speed, torque demand, and other operating parameters to optimize performance at each working point.
2Adaptability or versatility
If fixed geometric changes are made to counteract cogging torques, then the design is simplified, but the solution is not adaptable to different operating points
Solution Approach 1:
The system achieves adaptability through dynamic adjustment of the skewing angle. Multiple pitch elements can be independently adjusted to different angles based on real-time operating conditions, allowing the generator to adapt to various working points including different rotor speeds and torque demands without requiring multiple fixed designs.
Solution Approach 2:
The control unit implements feedback by continuously monitoring operating parameters (rotor speed, torque demand, current draw) and adjusting the skewing angle accordingly. This closed-loop control ensures the generator maintains optimal performance across different operating points by adapting the geometric configuration in real-time based on actual operating conditions.
3Ease of operation
If slot skewing is predetermined at the works, then manufacturing is simplified, but the solution cannot be changed during ongoing operation
Solution Approach 1:
The patent enables dynamic adjustment of the skewing angle during operation through actuated pitch elements. The control unit can modify the angular position of stator slots or rotor poles in real-time based on operating conditions, providing ease of operation by allowing continuous optimization without requiring complex manual reconfiguration or downtime for adjustments.
Data Source
AI summary
Provided is a method for controlling, by means of field-oriented closed-loop control, an active rectifier which is electrically connected to a stator of a generator of a wind turbine. The generator has a rotor which is mounted so as to be rotatable about the stator and comprises the steps of determining a mechanical position of the rotor with respect to the stator, predefining DC components of rotor-fixed d and q coordinates for at least one 3-phase stator current, determining an AC component for the q coordinate at least as a function of the mechanical position of the rotor, modulating the determined AC component of the q coordinate onto the predefined DC component of the q coordinate, so that a modulated q coordinate is produced which has a DC component and an AC component, and controlling the active rectifier at least as a function of the modulated q coordinate and preferably as a function of the d coordinate.