Wind Turbine Control System Using Split Power Reference Signals
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Solution Overview
Problem
Modern wind turbines face limitations in controlling power output due to the need to avoid passing power fluctuations to the electrical grid, and the requirement to emulate a synchronous generator can disrupt turbine control systems.
Innovation Solution
A method involving the generation of two distinct control reference signals - a turbine control reference signal and a grid control reference signal - allows for decoupling of the wind turbine's energy generation from the grid's energy transfer, enabling more effective damping and power control without disrupting the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power reference signal is used to control both turbine power generation and grid power transfer, then the control system is simple, but the turbine cannot apply large power variations for damping without passing fluctuations to the grid
Solution Approach 1:
The single power reference signal is segmented into two separate reference signals: a turbine control reference signal for the machine side converter and a grid control reference signal for the grid side converter. This segmentation allows independent optimization of each control objective, enabling the turbine to apply larger power variations for damping while the grid side converter compensates to maintain stable grid power transfer.
2Reliability
If the turbine control system applies large power variations for damping, then damping effectiveness improves, but power fluctuations are passed to the electrical grid
Solution Approach 1:
The grid side converter acts as an intermediary between the turbine and the electrical grid. It receives the grid control reference signal that compensates for power variations applied by the turbine, and adjusts the power transferred to the grid accordingly. This intermediary function allows the turbine to apply large power variations for damping while the grid side converter absorbs or compensates for these fluctuations, preventing them from being passed to the grid.
3Reliability
If a virtual synchronous machine concept is implemented, then grid disturbance smoothing is improved, but the turbine control system is disrupted
Solution Approach 1:
The control system is segmented into two independent control loops: one for turbine control and one for grid control. This segmentation allows the virtual synchronous machine concept to be implemented in the grid control loop without disrupting the turbine control loop, enabling grid disturbance smoothing while maintaining stable turbine operation.
4Speed
If pitch control is used to limit rotor speed during high winds, then rotor speed control is achieved, but pitch activity increases and drivetrain loads increase
Solution Approach 1:
The patent replaces mechanical pitch control with electrical torque control. Instead of using the pitch system to limit rotor speed during high winds, the machine side converter applies electromagnetic torque to the rotor to control its speed. This substitution reduces pitch activity and the associated mechanical loads on the drivetrain, while achieving the same rotor speed control objective.
Data Source
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AI summary
A method of controlling a wind turbine connected to an electrical grid is provided. The method comprises generating a turbine control reference signal and a grid control reference signal. The turbine control reference signal is provided to a machine side unit of a power or torque control system of the turbine to control the amount of energy generated by the turbine. The grid control reference signal is provided to a line side unit of the power or torque control system to control the amount of energy transferred to the electrical grid based on the grid control reference signal.