Generator Force Ripple Control via Harmonic Current Injection
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Solution Overview
Problem
Wind turbine generators face challenges in reducing acoustic noise and vibration due to air gap torque ripples and radial force pressure ripples, which are difficult to minimize simultaneously using existing design approaches, especially with variable speed generators where the frequency range of excitation is wide, making it costly and inefficient to avoid all resonance frequencies.
Innovation Solution
A method involving the use of harmonic current references to control force ripples by obtaining and filtering input signals for radial and tangential force ripples, and using transformation procedures to generate output signals for synchronous rotating frames, allowing for efficient minimization of torque and radial force pressure ripples through feedback mechanisms, potentially using a frequency converter to inject harmonic currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If mechanical parts are designed to place all resonance frequencies out of the excitation range, then noise and vibration are reduced, but this is very difficult due to variable speed generating a wide frequency range and size and cost limits
Solution Approach 1:
Instead of attempting to mechanically design the generator to avoid all resonance frequencies across the wide variable speed range, the patent uses feedback control to actively measure and counteract ripples at any operating frequency. The system adapts in real-time to the current operating point, eliminating the need for complex mechanical designs that would be required to cover the entire frequency range passively.
Solution Approach 2:
The patent transitions from a static mechanical design approach to a dynamic control approach. By continuously adjusting harmonic current references based on real-time measurements of torque and radial force pressure ripples, the system can adapt to any speed and load condition, effectively handling the wide frequency range without requiring complex mechanical designs for each operating point.
2Object-generated harmful factors
If existing wind turbines are improved to reduce noise and vibration, then acoustic noise and vibrations are reduced, but significant redesign or additional expenses are required
Solution Approach 1:
The patent replaces mechanical design modifications with an electrical control solution. Instead of physically redesigning the generator structure, magnets, or mechanical parts to reduce noise and vibration, the system uses electrical harmonic current injection controlled by a feedback mechanism. This substitution allows existing turbines to be upgraded with minimal hardware changes, primarily requiring only control system modifications rather than expensive mechanical redesigns.
Data Source
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AI summary
It is described: a method for providing a harmonic current reference, in particular for controlling force ripples of a generator, the method comprising: Obtaining a first input signal (IN1) indicative for a radial force ripple of a generator; obtaining a second input signal (IN2) indicative for a reference harmonic generator radial force; obtaining a third input signal (IN3) indicative for a tangential force ripple of the generator; obtaining a fourth input signal (IN4) indicative for a reference harmonic generator tangential force; obtaining a fifth input signal (IN5) indicative for an electrical angle of the generator; determining a first internal signal (int1) by filtering the first input signal (IN1) with taking into account the fifth input signal (IN5), the first internal signal (int1) being indicative for a radial force ripple comprising only a first harmonic component at a certain harmonic of a generator current; determining a second internal signal (int2) by filtering the third input signal (IN3) with taking into account the fifth input signal (IN5), the second internal signal (int2) being indicative for a tangential force ripple comprising only a second harmonic component at the certain harmonic of the generator current; determining a first output signal (OUT1) by a first transformation procedure (TP1) making use of the second input signal (IN2) and the first internal signal (int1), the first output signal (OUT1) being indicative for a certain harmonic current reference for a first axle of an synchronous rotating frame; and determining a second output signal (OUT2) by a second transformation procedure (TP2) making use of the fourth input signal (IN4) and the second internal signal (int2), the second output signal (OUT2) being indicative for a certain harmonic current reference for a second axle of the synchronous rotating frame.