Converter Impedance Measurement With Grid-Impedance Decoupling
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Solution Overview
Problem
Existing impedance measurement methods for converters face high costs, transportation difficulties, complex operations, and the need to disclose controller design, with secondary-side methods neglecting grid impedance considerations.
Innovation Solution
An impedance measurement method that superimposes positive-sequence current and voltage disturbances at sampling points of the converter, determining impedance values through transfer functions and decoupling coefficients, without modifying the primary-side circuit or requiring controller disclosure, accounting for grid impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If primary-side measurement method is used, then measurement precision is improved, but device complexity and ease of operation deteriorate due to high costs, transportation difficulties, and complex operations
Solution Approach 1:
The patent uses the converter's existing control loop as an intermediary to perform impedance measurement. Instead of directly connecting disturbance sources to the primary-side circuit, the measurement is conducted through the control loop which acts as a mediator, eliminating the need for external disturbance sources and complex primary-side modifications.
Solution Approach 2:
The patent creates a virtual model of the impedance measurement process by injecting disturbances into the control loop and calculating equivalent impedance values. This virtual copying of the measurement process avoids the need for physical primary-side modifications while maintaining measurement accuracy.
2Measurement precision
If primary-side measurement method is used, then measurement precision is improved, but ease of operation worsens due to complex operations and slow disturbance switching speed
Solution Approach 1:
The patent replaces the mechanical/electrical disturbance source system with a software-based control loop disturbance injection. Instead of using physical disturbance sources with slow switching speeds, the measurement is performed by injecting disturbances through the digital control loop, which operates much faster and is easier to implement.
3Device complexity
If secondary-side measurement method is used, then device complexity and ease of operation are improved, but measurement precision deteriorates due to lack of grid impedance consideration
Solution Approach 1:
The patent incorporates grid impedance considerations into the secondary-side measurement by using feedback from the control loop responses. The measurement process captures the interaction between the converter and grid impedance through the control loop, allowing accurate impedance determination without requiring primary-side access.
4Ease of operation
If secondary-side measurement method is used, then ease of operation is improved, but adaptability worsens due to requirement of controller disclosure and control loop modification
Solution Approach 1:
The patent creates a universal measurement method that can be applied to different converter types without requiring specific controller disclosures. By using the control loop as a generic interface for disturbance injection and measurement, the method becomes adaptable to various converter configurations while maintaining ease of operation.
Data Source
AI summary
An impedance measurement method and apparatus for a converter, an electronic device, and a medium are applied to the field of converter data calculation and processing. A positive-sequence current disturbance and a positive-sequence voltage disturbance are respectively superimposed at a current value sampling position and a voltage value sampling position of the converter, to obtain a first disturbance current value, a first disturbance voltage value, a second disturbance current value, and a second disturbance voltage value; a first to-be-measured impedance value and a transfer function are determined based on the obtained values; further, a second to-be-measured impedance value and an initial impedance value are determined based on the first to-be-measured impedance value, the transfer function, a filter equivalent impedance value, and relevant parameters of the converter, and a final target impedance value of the converter is determined based on the initial impedance value and a decoupling coefficient.