Wind Turbine Power Controller With Series DC Link Grid Integration
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Solution Overview
Problem
Current technologies lack a straightforward and simple method to jointly connect multiple small-scale wind turbines to the grid, making it difficult for households, businesses, and industries to efficiently supply wind-power-based electricity in a scalable manner.
Innovation Solution
A power controller system comprising a rectifier unit, direct-current output interface, processing unit, and DC-to-DC converter, which converts alternating current from wind turbines to stable direct current and allows multiple wind turbines to be connected to a common inverter unit, enabling scalable integration into the grid, with features like emergency braking and self-sufficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple small-scale wind turbines are connected to the grid using conventional technologies, then grid integration is achieved, but the system becomes complex and difficult to scale
Solution Approach 1:
The system divides the wind turbine integration into modular power controller units, where each unit independently processes AC to DC conversion for one or more wind turbines. These modular units can be easily added or removed to scale the system capacity without redesigning the entire connection architecture.
Solution Approach 2:
Multiple power controller units connect their DC outputs in parallel to a common inverter unit, which then feeds the grid. This merging approach allows multiple small-scale wind turbines to be collectively integrated into the grid through a unified interface, simplifying the overall connection while maintaining scalability.
2Reliability
If wind power is converted directly to grid frequency, then grid synchronization is achieved, but frequency instability occurs due to wind fluctuations
Solution Approach 1:
The system introduces a DC link as an intermediary between the variable-frequency AC output of wind turbines and the fixed-frequency AC grid. The rectifier converts AC to DC, stabilizing the energy form, and the inverter then converts DC to grid-synchronized AC, effectively decoupling the wind turbine's variable frequency from the grid's fixed frequency requirements.
Solution Approach 2:
The rectifier and inverter units dynamically adjust their conversion parameters to optimize power transfer. The rectifier controls DC voltage levels, and the inverter adjusts output frequency and phase to match grid requirements, allowing efficient power conversion while maintaining grid stability despite wind speed variations.
3Reliability
If power controllers are added for each wind turbine, then conversion stability is improved, but system cost and complexity increase
Solution Approach 1:
The power controller units are designed as universal modules that can handle multiple wind turbines. Each unit contains a rectifier and inverter that can process power from one or more turbines, reducing the total number of controllers needed while maintaining stable conversion for each turbine connection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates the convenient and scalable connection of multiple wind turbines to the grid, allowing for easy adjustment of capacity and ensuring stable energy output, while minimizing conversion losses and maintaining grid stability.
Implementation Method 1
The rectifier unit is configured to receive alternating electric current from the wind turbine generator and based thereon provide basic electric energy in the form of a base direct-current voltage
Implementation Method 2
an inverter unit, which, in turn, is arranged to produce output alternating power to the alternating current network based on the output direct-current voltages
Data Source
Figure 1~2
Figure 3
AI summary
A power controller (130a) controls an amount of electric output power from a wind turbine generator (121a) to an alternating current network. The power controller (130a) includes a rectifier unit receiving alternating electric current from the wind turbine generator (121a) and provides basic electric energy in the form of a base direct-current voltage. A direct-current output interface in the controller delivers an output direct-current voltage (DC+) based on the base direct-current voltage. The direct-current output interface is configured to be connected in series with the direct-current output interface of at least one additional power controller (130b, 130c) to an input interface (141) of an inverter unit (140) arranged to produce output alternating power (ACG) to the alternating current network based on the output direct-current voltages (DC+) from said in-series connected direct-current output interfaces.