Harmonic Control of Wind Turbine Generator Side Converters
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Solution Overview
Problem
Conventional harmonic control systems for generator side converters in wind turbines face issues such as reduced stability, poor dynamic performance, and inaccurate speed/position estimation due to the introduction of digital filters, which undermine system stability and affect outer control loops.
Innovation Solution
An arrangement and method for determining an operation parameter reference for a generator side converter, which includes a harmonic current reference calculation module, a fundamental current reference calculation module, a bandpass filter, and controllers to derive and combine fundamental and harmonic current errors, eliminating the need for additional digital filters and ensuring system stability by having the fundamental and harmonic current controllers work towards the same target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital filters are added to current feedbacks and voltage references, then harmonic control performance is improved, but system stability is undermined and stability margins are reduced
Solution Approach 1:
The control system is segmented into two independent parallel controllers: a fundamental current controller handling the fundamental frequency component and a harmonic current controller handling harmonic frequency components. Each controller processes its designated frequency range separately, allowing precise harmonic control without compromising overall system stability. The segmentation enables independent optimization of each controller's parameters.
Solution Approach 2:
A frequency-based intermediary mechanism is introduced where the system selectively processes fundamental and harmonic components through separate control pathways. The fundamental current controller and harmonic current controller act as intermediaries that divide and manage different frequency components independently, preventing the stability issues that arise from applying filters to the entire current signal.
2Use of energy by moving object
If bandwidth of the fundamental current control is reduced, then control effort is reduced, but dynamic performance is reduced and outer control loops are negatively affected
Solution Approach 1:
The current control is segmented into fundamental frequency control and harmonic frequency control that operate in parallel. This segmentation allows the fundamental current controller to maintain its original bandwidth and dynamic performance characteristics, while the harmonic current controller handles harmonic suppression independently, preventing the need to reduce fundamental controller bandwidth for harmonic control.
Solution Approach 2:
Instead of applying broad filtering that affects the entire current spectrum, the system applies targeted harmonic control only to specific harmonic frequency components. This partial action approach allows the fundamental current controller to operate with full bandwidth and dynamic performance while harmonic controllers address only the specific harmonic disturbances.
3Measurement precision
If digital filters are added to voltage references used as inputs to speed observer, then speed/position estimation accuracy is improved, but system stability is undermined
Solution Approach 1:
The speed observer inputs are processed through segmented frequency-based control pathways. The fundamental current controller and harmonic current controller independently manage their respective frequency components, allowing accurate speed and position estimation through the fundamental controller without requiring filtering that would compromise system stability.
Data Source
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AI summary
It is described an arrangement (229) for determining an operation parameter reference (262) for controlling a generator side converter (221) portion coupled to a generator (211), in particular of a wind turbine (100), the arrangement comprising: an arithmetic element (251) configured to derive a fundamental current error (252) by subtracting a, in particular unfiltered, generator output current (253) from a sum of a fundamental current reference (249) and at least one harmonic current reference (243); a fundamental current controller (254) adapted to determine a fundamental operation parameter reference (255) based on the fundamental current error (252); at least one other arithmetic element (256) configured to derive at least one harmonic current error (257) by subtracting a, in particular band pass filtered (253') according to the harmonics, generator output current from the at least one harmonic current reference (243); at least one harmonic current controller (259) configured to determine at least one harmonic operation parameter reference (260) based on the harmonic current error (257); still another arithmetic element (261) configured to determine the operation parameter reference (262) as sum of the fundamental operation parameter reference (255) and the at least one harmonic operation parameter reference (260).