Wind Turbine Reactive Current Control for Overspeed Protection
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Solution Overview
Problem
Wind turbine generators experience frequent stops and reduced service life due to overspeeds caused by strong gusts and oscillations in offshore installations, leading to extreme and fatigue loads that limit their operational efficiency and lifespan.
Innovation Solution
A control method that adjusts the reactive current in wind turbine generators to extend their speed range by setting different reactive current set points based on rotational speed, reducing voltage at the converter terminals and limiting operation time above a speed threshold to prevent overspeeds and disconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pitch system is used to control rotational speed at rated power, then the wind turbine generator can maintain constant speed, but it cannot respond quickly enough to sudden wind gusts causing overspeed conditions
Solution Approach 1:
The control method prepares the blade pitch in advance by positioning it at an intermediate angle before gusts occur. When overspeed is detected, the pitch system is already near the feather position and can complete the speed limitation action faster, preventing extreme overspeed conditions while maintaining reliability.
Solution Approach 2:
The invention dynamically adjusts the blade pitch angle based on real-time rotational speed measurements. Instead of static pitch control, the system continuously modifies the pitch angle in response to changing wind conditions, enabling faster response to gusts and improving both speed control and overspeed protection.
2Reliability
If the wind turbine generator stops during overspeed events, then safety is maintained, but operational efficiency and service life are reduced due to frequent stops and restarts
Solution Approach 1:
The control method applies gradual pitch adjustment in advance to cushion against sudden overspeed events. By progressively increasing the pitch angle before critical speeds are reached, the system smooths out speed excursions and prevents the need for emergency stops, maintaining both safety and operational continuity.
Solution Approach 2:
The invention maintains continuous power generation by preventing complete shutdowns during gusts. Through proactive pitch control, the system keeps the turbine operating throughout gust events, eliminating stop-start cycles and maximizing energy capture while ensuring safety through controlled speed limitation.
3Productivity
If the blade pitch is positioned for maximum energy capture, then productivity is maximized, but the wind turbine generator becomes vulnerable to overspeeds when wind speed exceeds thresholds
Solution Approach 1:
The system dynamically transitions the blade pitch from fine pitch (maximum energy capture) to intermediate or feather positions in response to rotational speed measurements. This dynamic adjustment allows the turbine to operate at maximum efficiency during normal conditions while automatically reducing captured power when gusts approach, maintaining both productivity and overspeed resistance.
Solution Approach 2:
The control method uses feedback from rotational speed sensors to continuously adjust the blade pitch angle. When speed approaches overspeed thresholds, the feedback signal triggers pitch adjustment to reduce energy capture, creating a self-regulating system that balances productivity and safety based on real-time conditions.
Data Source
AI summary
The control method of a wind turbine generator increases the speed range of wind turbine generators, maximizing the operation and efficiency thereof, in addition to lengthening their service life, on minimizing the extreme and fatigue loads to which the wind turbine generators are subject, and which are due mainly to the stops and disconnections thereof as a result of strong gusts of wind. More specifically, the control method of the present invention stands out essentially for being based on the control of the reactive current circulating through the electric generator, said reactive current control being carried out in accordance with the rotational speed (ωg) for the purpose of reducing the voltage at the converter terminals on the generator side, or rotor voltage (VR), which ultimately allows a transitional increase in the speed range of the wind turbine generator.