Type-4 Wind Turbine Damping Control Across Variable Oscillation Frequencies
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Solution Overview
Problem
Existing oscillation suppression methods for grid-tied type-4 wind turbine generators are ineffective in varying frequency scenarios, as they can only suppress oscillations within a narrow frequency band, requiring complex re-optimization and adjustments, leading to poor applicability and efficiency.
Innovation Solution
An oscillation active damping control method and system that constructs energy feedback models based on stored and dissipated energy functions and interaction energies between subsystems, adjusting the current reference value of the q-axis current inner loop to decrease stored energy over time, effectively suppressing oscillations across sub-synchronous and super-synchronous frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency domain analysis methods with parameter optimization and supplementary control branches are used, then oscillation suppression is achieved within a specific frequency range, but the applicable frequency band is narrow and re-optimization is required when oscillation frequency changes
Solution Approach 1:
The patent transforms the static frequency domain analysis method into a dynamic time domain energy feedback method. By using time-domain differential equations to model energy storage and dissipation, the system can dynamically adapt to varying oscillation frequencies without requiring re-optimization, thus resolving the contradiction between suppression effectiveness and frequency band adaptability
Solution Approach 2:
The patent changes the fundamental parameters of the control approach by transitioning from frequency-based parameters (resonant frequency, damping ratio) to energy-based parameters (stored energy, dissipated energy, energy feedback gain). This parameter transformation enables the system to maintain effectiveness across a broad frequency band by controlling energy flow rather than targeting specific frequencies
2Reliability
If frequency domain analysis methods are used, then oscillation suppression is achieved at certain frequency points, but the method is complex and requires re-adjustment when oscillation frequency varies
Solution Approach 1:
The patent extracts the essential characteristic of oscillation (energy exchange between storage and dissipation) from the complex frequency domain analysis framework. By focusing solely on energy feedback control, the system eliminates the need for complex frequency scanning, parameter optimization, and supplementary control branches, significantly simplifying the control structure while maintaining suppression effectiveness
Solution Approach 2:
The patent implements a closed-loop energy feedback mechanism where the controller continuously monitors the oscillation state, calculates the required energy feedback amount based on stored and dissipated energy functions, and adjusts the damping force in real-time. This feedback approach replaces the open-loop frequency domain tuning method, reducing complexity while improving adaptability to frequency variations
3Reliability
If frequency domain analysis methods are used, then oscillation suppression is achieved within a narrow frequency band, but the efficiency is low when oscillation frequency changes
Solution Approach 1:
The patent ensures continuous energy feedback control by establishing real-time differential equations that continuously calculate the energy storage and dissipation rates. This continuous action allows the system to immediately respond to frequency changes without the interruption of re-optimization cycles, maintaining high suppression efficiency across varying oscillation frequencies
Data Source
AI summary
The application relates to an oscillation active damping control method and system for grid-tied type-4 wind turbine generator. The method comprises: based on an interconnection model of multiple subsystems, constructing a stored energy function and a dissipated energy function of a current inner loop control subsystem, and interaction energy functions between the current inner loop control subsystem and other subsystems are constructed, then establishing an energy feedback model of Type-4 wind turbine generator; when the oscillation occurs, obtaining instantaneous angular frequency of the PLL, and then based on the energy feedback model, adjusting the current reference value of the q-axis current inner loop generated by the reactive power outer loop control subsystem, to make the stored energy function decrease with time, so as to suppress the oscillation.