Wind Turbine Power Control Using Phase-Angle Dynamic Braking
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Solution Overview
Problem
Existing offshore wind turbine power transmission systems in meshed configurations face challenges in handling faults, leading to potential overloading of power converters due to sudden increases in power flow when one HVDC line fails, exceeding their capacity.
Innovation Solution
A control system that monitors AC phase angles and their rates of change, triggering dynamic braking systems to reduce power output and adjust phase angles to manage power flow, using blade pitch control and impedance to maintain stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a meshed configuration interconnection scheme is used for offshore wind turbine power transmission, then power transmission capability and system reliability are improved, but the risk of power converter overload during faults increases
Solution Approach 1:
The control system continuously monitors AC phase angles and their rates of change before faults occur, enabling early detection of abnormal conditions. When threshold violations are detected, the system proactively activates dynamic braking and adjusts power converter phase angles to prevent overload conditions from developing, rather than reacting after overload occurs.
Solution Approach 2:
The system implements closed-loop feedback by continuously monitoring AC phase angles and their rates of change, comparing them against predefined thresholds, and automatically adjusting power converter output and dynamic braking activation based on real-time conditions. This feedback mechanism enables the system to adapt to changing grid conditions and prevent overload during faults.
2Reliability
If dynamic braking system is activated to reduce instantaneous power output during faults, then power converter overload is prevented, but power transmission efficiency decreases
Solution Approach 1:
The system dynamically adjusts the activation and modulation of dynamic braking based on real-time AC phase angle monitoring. Rather than static braking activation, the control system modulates braking intensity according to the severity and duration of fault conditions, optimizing the balance between protecting power converters and maintaining power transmission efficiency during transient disturbances.
Solution Approach 2:
The control system employs periodic monitoring of AC phase angles and implements intermittent dynamic braking activation based on threshold violations. This periodic control approach allows the system to maintain normal operation during healthy conditions and only activate braking when necessary, minimizing efficiency losses while ensuring converter protection during faults.
3Stability of the object's composition
If phase angle adjustment is used to manage power flow during faults, then power distribution stability is improved, but control system complexity increases
Solution Approach 1:
The system manages power flow by dynamically adjusting the phase angle parameter of power converters based on monitored AC phase angle deviations. This parameter-based control approach simplifies the complexity by focusing on a single key parameter (phase angle) rather than controlling multiple variables simultaneously, while still achieving effective power flow management and stability during faults.
Data Source
AI summary
There is provided a control system for controlling power transmission associated with a first wind turbine. 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, to reduce an instantaneous power output of the first wind turbine.