PLL Power Angle Feedforward for Faster Wind Turbine Power Response
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Solution Overview
Problem
In wind turbine power systems, the response to power commands is sluggish in weak grids, leading to delays that can be detrimental to rapid power changes required for system stability, such as in drivetrain damper and fast power reduction functions.
Innovation Solution
The implementation of a power angle feedforward signal within a phase locked loop (PLL) of the power system, which estimates the power angle based on power commands and grid conditions, and uses this signal to control the power conversion assembly, reducing the need for closed-loop adjustments and thus minimizing delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional phase locked loop (PLL) is used for power conversion control, then the system structure is simple and reliable, but the response to power commands is sluggish with significant delay
Solution Approach 1:
The patent applies preliminary action by estimating the future power angle using a feedforward signal based on the power command and grid conditions. This estimated angle is provided in advance to the PLL, allowing the system to anticipate and prepare for upcoming power changes rather than merely reacting to them, thereby reducing the response delay.
2Productivity
If the power converter relies on closed-loop PLL adjustments to respond to power commands, then the control is stable, but the response is slow and cannot meet rapid power change requirements
Solution Approach 1:
The patent introduces a power angle feedforward signal as an intermediary element between the power command and the PLL controller. This feedforward signal acts as a mediator that provides the PLL with advance information about the required power angle, enabling faster response without compromising the stability provided by the closed-loop control.
3Reliability
If the wind turbine system uses conventional control without power angle feedforward, then the control system is simple, but the response to power commands is sluggish in weak grids
Solution Approach 1:
The power angle feedforward signal performs preliminary action by calculating and providing the anticipated power angle to the PLL before the actual power change occurs. This allows the control system to be proactive rather than reactive, significantly improving the response speed while maintaining system stability through the preserved closed-loop feedback mechanism.
Data Source
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AI summary
A method for reducing a delay between a power command and actual power of a power system includes receiving, via a power angle estimator, a power command of the power system. The method also includes receiving, via the power angle estimator, one or more grid conditions of the power grid. Further, the method includes estimating, via the power angle estimator, a power angle signal across the power system based on the power command and the one or more grid conditions. Moreover, the method includes receiving, via a phase locked loop (PLL), the estimated power angle signal. In addition, the method includes generating, via the PLL, a PLL phase angle signal based, at least in part, on the estimated power angle signal. Thus, the method further includes controlling, via a converter controller, a power conversion assembly of the power system based on the PLL phase angle signal.