Wind Power Converter Fault Detection With Current Limiting
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Solution Overview
Problem
Existing voltage-impressing and synchronous machine-emulating methods for converters in regenerative generating units are not designed to handle grid faults, such as voltage dips, sudden phase shifts, and frequency gradients, which can lead to unstable operation in the electrical power supply grid.
Innovation Solution
A closed-loop control method for converters in wind power installations that detects grid faults and limits the output current using current limitation, allowing the converter to operate as a virtual synchronous machine, with dynamic and steady-state current limitation mechanisms to manage sudden changes and maintain grid stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the converter operates in voltage-impressing mode to emulate a synchronous machine, then the converter can provide stable voltage and frequency support to the grid, but the converter becomes vulnerable to grid faults such as voltage dips and phase shifts that can cause unstable operation
Solution Approach 1:
The patent applies preliminary anti-action by implementing a fault detection mechanism that identifies grid faults before they can cause unstable operation. The controller continuously monitors grid conditions and detects faults such as voltage dips and phase shifts, enabling the converter to take preventive action by switching from voltage-impressing mode to current-impressing mode before instability occurs.
Solution Approach 2:
The patent implements dynamics by enabling the converter to dynamically switch between two operating modes: voltage-impressing mode for normal stable operation and current-impressing mode for fault conditions. This dynamic adaptability allows the converter to maintain reliability across varying grid conditions by adjusting its control strategy based on real-time grid status.
2Reliability
If the converter limits output current during grid faults, then excessive current injection is prevented and stable operation is maintained, but the converter cannot provide full power support to the grid during fault conditions
Solution Approach 1:
The patent applies dynamics by implementing a dynamic control mode switch that adapts the converter's behavior to grid conditions. During normal operation, the converter operates in voltage-impressing mode to provide maximum power support. Upon detecting a grid fault, it dynamically switches to current-impressing mode with current limiting to maintain stable operation, and can switch back to voltage-impressing mode when the fault is resolved, thus optimizing productivity across different operating conditions.
Solution Approach 2:
The patent applies partial action by implementing current limiting during fault conditions, where the converter provides partial power support rather than full power support. This partial action is sufficient to maintain stable operation during faults while preventing excessive current injection, and the converter can resume full power support when grid conditions return to normal.
Data Source
AI summary
The present disclosure relates to a method for operating a converter on a three-phase electrical power supply grid, comprising the following steps: operating the converter in a first operating mode by means of a control unit for generating an output current, wherein the converter in the first operating mode operates in such a way as to apply a voltage to the electrical power supply grid; detecting a grid fault on the electrical power supply grid by means of a detection means during the first operating mode; limiting the output current of the converter by means of current limitation when a grid fault on the electrical power supply grid has been detected during the first operating mode, in particular in such a way that the output current of the converter falls below a predetermined maximum current or substantially corresponds thereto.