Wind Turbine Current Control During Grid Faults
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Solution Overview
Problem
Existing wind turbine generators face challenges in accurately controlling rotor currents during abnormal power grid events, such as low-voltage ride through (LVRT), undervoltage ride through (UVRT), over-voltage ride through (OVRT), and high-voltage ride through (HVRT), which can lead to inadequate active and reactive power support.
Innovation Solution
A method and system that shifts the operation from power mode to current mode during abnormal events, utilizing closed control loops with active and reactive current regulators to accurately manage total active and reactive currents, ensuring the wind turbine generator remains connected and provides necessary power support by adjusting rotor voltage references and using software-controlled voltage sensors to detect grid voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If feed-forward implementation is used for current mode operation during abnormal grid events, then the control system responds to input signals in a pre-defined manner, but the rotor current reference accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual grid voltage during abnormal events and using this measured value to dynamically adjust the rotor current reference. The control system continuously monitors grid conditions and feeds this information back to the current reference calculation, ensuring accuracy adapts to real-time grid states rather than relying on pre-defined responses.
Solution Approach 2:
The patent dynamically changes the rotor current reference parameters based on measured grid voltage conditions. During abnormal grid events, the system adjusts current reference values in real-time according to actual voltage measurements, transforming static pre-defined parameters into dynamic adaptive parameters that maintain accuracy under varying grid conditions.
2Reliability
If wind turbine generator disconnects from power grid during abnormal events, then protection is provided, but active and reactive power support is lost
Solution Approach 1:
The patent uses the grid-side converter as an intermediary component that enables the wind turbine generator to remain connected to the power grid during abnormal events while providing active and reactive power support. The converter acts as a mediator that protects the generator from severe grid disturbances while maintaining the connection, allowing continuous power support without direct disconnection.
Solution Approach 2:
The patent implements protective measures beforehand by using the grid-side converter to cushion the generator against abnormal grid events. The converter is pre-configured to handle voltage sags and other abnormalities, providing a buffer that protects the generator while maintaining grid connection and power support capability throughout the abnormal event.
Data Source
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AI summary
Aspects of the present invention relate to a method for controlling an amount of power to be delivered from a wind turbine generator to a power grid during an abnormal power grid event, the method comprising the steps of detecting an abnormal power grid event; controlling an active current delivered to the power grid in response to a measured or determined total active current; and controlling a reactive current delivered to the power grid in response to a measured or determined total reactive current. Aspects of the present invention further relate to a computer program product for carrying out the method as well as a wind turbine generator being capable of carrying out embodiments of the invention.