Wind Park Current Control via Impedance Compensation
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Solution Overview
Problem
Wind farms face challenges in controlling current during grid faults, leading to potential voltage collapse and non-compliance with grid codes, especially in weak grid conditions, as existing solutions require complex feedback loops and do not account for impedance in current transmission.
Innovation Solution
A method that accounts for impedance between current generators and the point of common coupling to determine optimal reactive and active currents, allowing wind parks to stabilize the grid without complex feedback loops, using current generators like STATCOM and energy storage units to provide optimal current injection based on grid code requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wind turbines increase reactive current output during grid faults to stabilize the grid, then grid stability is improved, but the current injected into the grid does not reach the optimal value due to impedance in transmission lines
Solution Approach 1:
The controller pre-calculates the impedance of transmission lines and transformer before grid faults occur. This preliminary determination of impedance values enables the system to accurately compute the required current injection from individual wind turbines, ensuring that the injected current precisely achieves the optimal stabilization effect at the PCC without requiring complex real-time feedback adjustments
Solution Approach 2:
The controller acts as an intermediary that receives the optimal current reference at the PCC, calculates the required current from each wind turbine by compensating for transmission line and transformer impedance, and sends the adjusted current reference to individual turbines. This intermediary calculation ensures accurate current injection despite the presence of impedance in the transmission path
2Measurement precision
If complex feedback loops are used to control current injection during grid faults, then current control precision is improved, but system complexity increases
Solution Approach 1:
The system performs preliminary calculation of transmission line and transformer impedance before grid faults occur. By having these impedance values pre-determined, the controller can directly calculate the required current injection without needing complex real-time feedback loops, achieving precise current control through open-loop calculation based on pre-stored impedance data
Solution Approach 2:
The invention extracts and uses the impedance characteristics of transmission lines and transformer as separate, pre-determined parameters. By taking out these impedance values as known quantities for calculation, the system avoids the need for complex feedback mechanisms while maintaining accurate current control through straightforward impedance compensation calculations
Data Source
Figure 1
Figure 2a~2b
Figure 3a
AI summary
A method for controlling a current in a wind park is provided. The wind park comprises at least one wind turbine and at least one current generator. The method comprises detecting a grid irregularity, determining an optimal current to be provided at a predetermined location in the wind park during the grid irregularity and determining a corresponding current to be generated from the at least one current generator so as to provide the optimal current at the predetermined location. The corresponding current is determined based on at least an impedance value between the at least one current generator and the predetermined location.