Wind Turbine Dynamic Braking for Meshed Grid Fault Control
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Solution Overview
Problem
Offshore wind turbines connected via a meshed configuration face challenges in managing faults within the interconnection scheme, leading to potential power overload and instability in power transmission.
Innovation Solution
A control system is implemented to monitor AC phase angles and their rate of change between wind turbines and power converters. When thresholds are exceeded, the system activates the dynamic braking system (DBS) to reduce power output and maintains limited power through blade pitch control, ensuring stable power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wind turbine continues to transmit power through alternative paths during a fault, then power transmission continuity is maintained, but power overload and instability occur in the remaining healthy links
Solution Approach 1:
The control system applies preliminary anti-action by detecting phase angle changes that indicate fault conditions and preemptively reducing power output through dynamic braking before the system can enter an overloaded unstable state. This prevents the harmful effects of power overload by counteracting the tendency toward overload before it occurs.
Solution Approach 2:
The system employs feedback control by continuously monitoring AC phase angles and using this information to adjust power output in real-time. When phase angle changes indicate a fault condition, the feedback loop triggers dynamic braking to reduce power transmission, thereby preventing power overload while maintaining stable operation through closed-loop control.
2Object-affected harmful factors
If the dynamic braking system is activated to reduce instantaneous power output, then power overload is prevented, but steady-state power transmission is reduced
Solution Approach 1:
The system applies dynamics by using dynamic braking to create temporary, controlled resistance during fault conditions rather than permanent power reduction. The braking force is dynamically adjusted based on real-time phase angle monitoring, allowing the system to prevent power overload during transient fault conditions while minimizing impact on steady-state power transmission capability when the system returns to normal operation.
3Stability of the object's composition
If the system monitors and responds to phase angle changes to maintain stability, then power transmission stability is improved, but system complexity increases
Solution Approach 1:
The system applies parameter changes by monitoring the AC phase angle parameter and using changes in this parameter as the trigger for control actions. This approach maintains power transmission stability by detecting fault conditions through phase angle variations and responding with appropriate power reduction, while keeping the control logic relatively simple by focusing on a single key parameter rather than requiring complex multi-parameter analysis.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
There is provided a control system for controlling power transmission associated with a first wind turbine (200) in a power transmission system. The control system is configured to: monitor an alternating current, AC, phase angle associated with the first wind turbine and/or monitor a rate of change of the AC phase angle associated with the first wind turbine; determine whether there is a change in the AC phase angle which is above a first threshold value and/or determine whether the rate of change of the AC phase angle is above a second threshold value; and in response to determining that there is a change in the AC phase angle which is above the first threshold value and/or the rate of change of the AC phase angle is above the second threshold value, cause the first wind turbine to operate its dynamic braking system, DBS (250), to reduce an instantaneous power output of the first wind turbine.