Grid-Forming VSM Control With Damper Winding Emulation
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Solution Overview
Problem
Wind turbines operating in grid-forming mode as virtual synchronous machines experience power oscillations during extreme grid events, leading to increased drivetrain loads and potential non-compliance with grid codes, which can result in turbine trip and failure to ride through faults.
Innovation Solution
Implementing a power angle compensation method akin to damper winding compensation, where an additional power angle is introduced to the inertial power regulator to dampen power oscillations and reduce drivetrain loads, derived from the error between power command and feedback inputs, and further adjusted using torsion-induced damping torque to mitigate hunting oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wind turbines operate in grid-forming mode as virtual synchronous machines, then the ability to support grid voltage and frequency is improved, but power oscillations during extreme grid events increase leading to higher drivetrain loads
Solution Approach 1:
The patent introduces a power angle compensation mechanism that acts as an intermediary between the inertial power regulator and the converter control. This compensation mechanism processes the power angle information and applies corrective actions to dampen oscillations, effectively mediating between the grid-forming control function and the power oscillation issue.
Solution Approach 2:
The patent implements a feedback loop where the power angle is continuously monitored and fed back to the power angle compensation mechanism. This feedback enables the system to detect oscillations and apply appropriate compensation to dampen them, creating a closed-loop control system that actively manages power oscillations while maintaining grid-forming capability.
2Strength
If power angle compensation is applied to dampen oscillations, then drivetrain loads are reduced, but control system complexity increases
Solution Approach 1:
The power angle compensation mechanism is designed to perform multiple functions: it dampens power oscillations, reduces drivetrain loads, and maintains grid-forming capability. By consolidating these functions into a single control mechanism, the patent avoids the need for separate complex control systems for each function.
Solution Approach 2:
The patent merges the power angle compensation function with the existing inertial power regulator and converter control systems. Rather than adding entirely separate control mechanisms, the compensation is integrated into the existing control architecture, sharing computational resources and control pathways to minimize overall system complexity.
Data Source
AI summary
A method and associated system provide grid-forming mode (GFM) control of an inverter-based renewable energy source having an asynchronous machine connected to a power grid. The method includes deriving a power error signal (PER) between a real power output (PB) from the renewable energy source and a power reference (PREF) representing a desired power output of the renewable energy source. With an inertial power regulator, a phase shift angle (δIT) is generated from the power error signal (PER) to provide virtual synchronous machine (VSM) control functionality to the GFM control of the renewable energy source. A power angle compensation (Δδ) is applied to the phase shift angle (δIT) from the inertial power regulator to dampen power oscillations and load fluctuations during transient power events.