Wind Turbine Grid Fault Control via Setpoint Freezing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wind energy installations face instability and power fluctuations during and after grid faults, leading to reduced power delivery and potential speed overshoots or undershoots, which can strain the system and cause undesirable power releases into the grid.
Innovation Solution
A method that detects grid faults by monitoring voltage and frequency changes, freezes the current power setpoint, and gradually adjusts the permissible power range to stabilize the wind turbine's speed, preventing sudden power releases by increasing the maximum permissible setpoint value over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power setpoint is rapidly adjusted after a grid fault to restore power delivery, then power delivery is improved, but speed stability deteriorates causing overshoots and undershoots
Solution Approach 1:
The patent applies preliminary action by detecting grid faults early through voltage and frequency monitoring, and by gradually increasing the maximum permissible setpoint value over time rather than making sudden adjustments. This gradual approach allows the system to adapt to post-fault conditions while maintaining speed stability, preventing overshoots and undershoots that would occur with rapid power restoration.
2Stability of the object's composition
If the blade pitch angle is adjusted to maintain nominal speed during grid faults, then speed stability is improved, but power delivery deteriorates to zero
Solution Approach 1:
The patent applies dynamics by making the power setpoint adaptable rather than fixed. During grid faults, the system dynamically adjusts the maximum permissible setpoint value over time, allowing power delivery to be reduced during the fault while enabling gradual restoration afterward. This dynamic approach replaces the static blade pitch angle adjustment with a time-varying power setpoint that balances speed stability and power delivery needs.
3Stability of the object's composition
If the power setpoint is frozen during grid faults to maintain stability, then speed stability is improved, but power delivery deteriorates and stored energy cannot be released
Solution Approach 1:
The patent applies preliminary action by preparing a gradual setpoint restoration strategy before the fault fully impacts the system. Instead of simply freezing the setpoint, the system begins gradually increasing the maximum permissible setpoint value during the fault condition, enabling controlled energy release while maintaining stability. This preliminary gradual adjustment prevents the complete power delivery loss associated with full setpoint freezing.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The method involves detecting actual value of a variable of a wind power plant. A hold setpoint is preset for the variable during a holding time, where holding reference value corresponds to the actual value of the variable. A maximum permissible setpoint for the variable is determined, where the maximum setpoint is increased when the hold time is elapsed. The plant is controlled with a reference preset that corresponds to a rotational speed. A presetting of the maximum setpoint is ended when rotational speed-dependent setpoint is lower than the maximum setpoint. An independent claim is also included for a wind power plant.