DFIG Rotor Control for Series-Compensated Wind Oscillation Damping
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Solution Overview
Problem
Conventional methods for suppressing sub-synchronous oscillation in wind power plants with series compensation are complex, requiring detection of multiple frequency information and are not adaptable to weak power grids with varying series compensation degrees, leading to unstable operation and control failures.
Innovation Solution
A method involving a filter to extract dynamic small signals, a PID negative feedback controller, and a power oscillation damping (POD) controller to feed forward terms into rotor voltage and current controllers, along with phase and amplitude compensations, to suppress oscillations in a doubly-fed generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods for suppressing sub-synchronous oscillation are used, then oscillation suppression is attempted, but the control structure becomes complex and requires detection of multiple frequency information
Solution Approach 1:
The patent extracts only the necessary oscillation components from the complex multi-frequency signal using selective filtering. Instead of detecting all frequency components, the method extracts specific sub-synchronous oscillation components that need suppression, simplifying the control structure while maintaining effectiveness.
Solution Approach 2:
The control method segments the oscillation suppression task into distinct frequency components. By separating sub-synchronous oscillation from other signal components through filtering, the patent enables independent control of each oscillation mode, reducing overall system complexity.
2Reliability
If conventional methods detect and identify all sub-synchronous voltage and current frequencies, then comprehensive oscillation control is achieved, but the detection and identification process becomes complex and difficult
Solution Approach 1:
The patent extracts only the critical sub-synchronous oscillation components from the full spectrum of voltage and current signals. By using band-pass filters tuned to specific sub-synchronous frequencies, the method obtains the necessary frequency information without performing complex full-spectrum analysis.
Solution Approach 2:
Instead of detecting and controlling all possible frequency components, the patent applies partial action by focusing only on the dominant sub-synchronous oscillation frequencies that pose the greatest threat to system stability. This selective approach reduces detection complexity while maintaining sufficient control effectiveness.
3Reliability
If a comprehensive sub-synchronous controller is designed to handle all oscillation modes, then all oscillation frequencies can be controlled, but the control parameter design becomes complex
Solution Approach 1:
The patent segments the control problem into separate frequency-specific control loops. Each sub-synchronous oscillation mode is controlled independently with its own simplified controller parameters, avoiding the need to design complex parameters for a unified multi-frequency controller.
Solution Approach 2:
The patent changes the control parameters dynamically based on the detected oscillation frequency. By adjusting controller gains and parameters according to the specific sub-synchronous mode present, the system achieves effective control across multiple frequencies while keeping individual parameter designs simple.
4Ease of operation
If conventional control methods are applied to weak power grids with different series compensation degrees, then standard control is maintained, but adaptability to varying grid conditions is poor
Solution Approach 1:
The patent implements dynamic adaptation by continuously monitoring the series compensation degree and grid conditions. The controller parameters and filter frequencies are dynamically adjusted based on the detected oscillation characteristics, enabling the system to adapt to varying grid conditions while maintaining ease of operation through automated tuning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method stabilizes power grid operation by effectively damping oscillations, improving control performance and adaptability to weak power grids with varying series compensation, ensuring stable operation of wind power plants.
Implementation Method 1
extracting, by a filter, a first dynamic small signal from first relevant parameters causing power oscillation
Implementation Method 2
inputting the first dynamic small signal to a proportional-integral-differential (PID) negative feedback controller
Implementation Method 3
performing phase and amplitude compensations on the third dynamic small signal
Implementation Method 4
performing phase and amplitude compensations on the third dynamic small signal
Implementation Method 5
The method stabilizes power grid operation by effectively damping oscillations
Data Source
AI summary
A method, an apparatus, a device and a system for controlling an oscillation damping caused by a series compensation for a wind power plant are provided. The method includes: extracting, a first dynamic small signal from first relevant parameters causing power oscillation, inputting the first dynamic small signal to a PID controller, and feeding an output control parameter from the PID to a rotor voltage controller as a first feedforward term; obtaining, according to second relevant parameters causing sub-synchronous oscillation, a virtual voltage, and feeding into a rotor voltage controller as a second feedforward term; and extracting a third dynamic small signal from third relevant parameters causing the oscillation of a rotor current loop and then performing phase and amplitude compensations on the third dynamic small signal, and feeding the output of the POD controller into the given position of a rotor current controller as a third feedforward term.