Double-Fed Generator Control for Grid-Forming Torsional Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wind turbines operating as grid-forming assets face challenges in managing drivetrain damper oscillations during transient grid events, which can lead to undesirable torsional vibrations and power fluctuations, conflicting with the need to maintain grid frequency and voltage stability.
Innovation Solution
A method and system for a double-fed generator connected to a power grid, utilizing a controller with frequency and voltage modules to determine stator-frequency errors, separate torsional and stator components, and combine damping power commands with power output requirements to generate consolidated control commands, ensuring grid-forming voltage and frequency while damping torsional vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the wind turbine operates as a grid-forming asset to maintain grid voltage and frequency stability, then grid stability is improved, but drivetrain damper oscillations and torsional vibrations increase
Solution Approach 1:
The controller segments the frequency error into two distinct components: a stator frequency error component and a drivetrain damper oscillation component. This segmentation allows independent handling of each component - the stator frequency error is used for grid-forming control while the drivetrain damper oscillation component is used to generate damping torque commands, thereby resolving the conflict between grid stability and drivetrain vibrations
Solution Approach 2:
The controller acts as an intermediary by receiving both grid-forming torque commands and drivetrain damper torque commands, combining them through superposition to generate a unified generator torque command. This intermediary function allows both grid stability requirements and drivetrain vibration damping to be satisfied simultaneously without direct conflict
2Object-generated harmful factors
If damping torque commands are generated to reduce drivetrain oscillations, then torsional vibrations are reduced, but conflicts arise with grid-forming control commands
Solution Approach 1:
The controller merges the grid-forming torque command and the drivetrain damper torque command through superposition to create a consolidated generator torque command. This merging approach allows both control objectives (grid-forming and vibration damping) to be achieved simultaneously without requiring separate control systems or complex coordination mechanisms
Solution Approach 2:
The controller dynamically changes the torque command parameter by adding the damping torque component to the grid-forming torque component. This parameter modification allows the system to adapt to drivetrain oscillations while maintaining grid-forming functionality, effectively reducing torsional vibrations without compromising grid stability
Data Source
AI summary
The system and method described herein provide grid-forming control of a power generating asset having a double-fed generator connected to a power grid. Accordingly, a stator-frequency error is determined for the generator. The components of the stator frequency error are identified as a torsional component corresponding to a drivetrain torsional vibration frequency and a stator component. Based on the stator component, a power output requirement for the generator is determined. This power output requirement is combined with the damping power command to develop a consolidated power requirement for the generator. Based on the consolidated power requirement, at least one control command for the generator is determined and an operating state of the generator is altered.