Inverter-Based Drivetrain Resonance Decoupling From Grid Active Power
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Solution Overview
Problem
Conventional wind turbines face challenges in decoupling drivetrain-related power oscillations from active power injected into the electrical grid, especially as synchronous machines are retired, necessitating alternative solutions to manage power dynamics independently of external electrical system conditions.
Innovation Solution
An inverter-based resource system with a power converter, generator, and energy buffer, controlled by a processor to receive and filter voltage feedback signals, determine current or power commands, and adjust the power converter and energy buffer to reduce or eliminate drivetrain resonance mode oscillations, thereby decoupling mechanical drivetrain resonance from the external electrical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional current source control is used to inject specified current into the grid based on fundamental voltage waveforms, then the wind turbine can operate with simple control logic, but the drivetrain-related power oscillations cannot be decoupled from the active power injected into the grid
Solution Approach 1:
The patent segments the power injection control into two independent components: fundamental current injection for active power and oscillation current injection for drivetrain resonance damping. The controller separates these functions by generating different current components at different frequencies, allowing simple base control while adding oscillation decoupling capability through superposition of current vectors.
Solution Approach 2:
The patent introduces an intermediary oscillation current component that acts as a mediator between the drivetrain oscillations and the grid. This intermediate current, generated at the drivetrain resonance frequency, decouples the oscillations from the active power by providing a separate pathway for oscillation energy, preventing them from propagating into the grid while maintaining simple fundamental control.
2Adaptability or versatility
If grid-forming resources are abundantly available to accommodate active power changes, then wind turbines can freely change power into the grid for damping control functions, but as synchronous machines are retired, the ability to freely change power becomes constrained
Solution Approach 1:
The patent replaces the mechanical/synchronous grid-forming resources with an inverter-based control system. Instead of relying on synchronous machines to accommodate power changes, the invention uses power electronic converters with advanced control algorithms to generate oscillation-damping currents, substituting mechanical grid inertia with electronic control capability.
Solution Approach 2:
The patent changes the control parameters by injecting current at specific frequencies corresponding to drivetrain resonance modes. By modifying the current injection strategy from fundamental frequency only to include harmonic frequencies, the system achieves oscillation damping while adapting to grids with reduced synchronous machine presence.
3Reliability
If power oscillation components are injected at known frequencies dictated by wind turbine dimensions and physics, then drivetrain torsional oscillations can be damped, but the oscillations may be injected into the grid causing disturbances
Solution Approach 1:
The patent implements feedback by continuously monitoring grid voltage and current to detect drivetrain oscillation frequencies and amplitudes. The controller uses this feedback information to adjust the oscillation current injection in real-time, ensuring effective damping while adapting to changing grid conditions to minimize disturbance propagation.
Solution Approach 2:
The patent makes the control system dynamic by adjusting the oscillation current injection based on real-time detection of drivetrain resonance frequencies. Instead of fixed-frequency injection, the system dynamically adapts the injection frequency and amplitude to match the actual drivetrain oscillation characteristics, optimizing damping effectiveness while minimizing grid disturbances.
Data Source
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AI summary
A method for decoupling a mechanical drivetrain resonance mode of an inverter-based resource from the external electrical system includes receiving one or more voltage feedback signals at a node between the inverter-based resource and the external electrical system. The method also includes filtering the one or more voltage feedback signals to extract changes in a voltage at a frequency associated with the drivetrain resonance mode. Further, the method includes determining at least one current command or power command based on the filtered one or more voltage feedback signals. Moreover, the method includes controlling the power converter according to the at least one current command and controlling the energy buffer according to the power command so as to reduce or eliminate the changes in the voltage at the frequency associated with the drivetrain resonance mode.