Sub-grid Reactive Power Control for Wind Farm Grid Stability
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Solution Overview
Problem
Large wind farms face inefficiencies in reactive power control due to differences in reactive power production among individual turbines, leading to inefficient operation and increased costs from long electrical connections and potential transformer stress.
Innovation Solution
A reactive power controller system that includes sub-grid measurement devices and controllers to measure and adjust reactive power components at each sub-grid, allowing for individual control of wind turbines to achieve a desired reactive power value and power factor, thereby optimizing wind farm operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large wind farm covers an increasing area to accommodate more wind turbines, then the power generation capacity increases, but the difference in reactive power production among individual turbines increases due to topology variations, making control less efficient
Solution Approach 1:
The wind farm is divided into multiple sub-grids, each with its own measurement device and controller. This segmentation allows reactive power to be controlled locally at the sub-grid level rather than requiring centralized control of all turbines, improving control efficiency despite the large overall farm size and topology variations.
Solution Approach 2:
Each sub-grid is equipped with dedicated measurement devices and controllers that adapt to the specific topology and reactive power characteristics of that local area. This local quality approach allows each sub-grid to be optimized independently, addressing the varying reactive power production caused by different positions and connections within the large wind farm.
2Device complexity
If identical or nearly identical commands are used for all wind turbines to compensate reactive power, then the control system is simplified, but the control efficiency decreases due to topology differences among turbines in large wind farms
Solution Approach 1:
The control system is segmented into multiple sub-grid controllers, each managing a specific sub-grid. This segmentation maintains relative simplicity at each control node while improving overall efficiency, as each controller only needs to manage local turbines rather than coordinating all turbines across the entire wind farm.
Solution Approach 2:
The control approach transitions from a single centralized control dimension to multiple distributed control dimensions (one per sub-grid). This dimensional change allows parallel control operations across sub-grids, improving compensation efficiency without proportionally increasing overall system complexity.
3Adaptability or versatility
If long electrical connections are used to connect individual wind turbines to the collector bar in large wind farms, then all turbines can be connected to the utility grid, but the cost increases and potential transformer stress occurs
Solution Approach 1:
The electrical connection system is segmented into multiple sub-grids, each with its own measurement and control infrastructure. This segmentation allows for more distributed and optimized electrical pathways, reducing the need for excessively long single-point connections to the collector bar and thereby reducing energy losses.
Solution Approach 2:
Sub-grids act as intermediary structures between individual wind turbines and the main collector bar/utility grid connection. These intermediaries allow for localized reactive power management and more efficient electrical distribution, reducing the stress on main transformers and minimizing energy losses in long connection cables.
Data Source
AI summary
A reactive power controller for controlling reactive power in a wind farm grid connected to a utility grid and including at least two sub-grids and a collector portion is provided. At least one wind turbine is connected to each sub-grid, wherein the at least two sub-grids are connected to the collector portion and wherein the collector portion establishes the connection to the utility grid. The reactive power controller includes a device for determining an actual reactive power value at the collector portion, and a wind farm controller operatively connected to the device for controlling at least one of said wind turbines on basis of the determined actual reactive power value such that a desired reactive power value is attained.