Wind Turbine Transformer Compensation for Reactive Power Range
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Solution Overview
Problem
Wind power plants face challenges in efficiently providing reactive power to the electrical power system due to limitations in wind turbine power converter headroom and transformer turns ratio, which restricts voltage control and increases losses.
Innovation Solution
A method involving the use of passive devices connected to a transformer to dynamically control reactive power, allowing the power converter to operate within optimal voltage ranges by ramping reactive power and adjusting the reactive contribution of the passive devices, thereby optimizing reactive power transmission between wind turbines and the power system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the nominal voltage at the secondary side of the transformer is decreased to increase reactive power capability, then the reactive power export capability is improved, but the converter current increases which increases losses and requires more current headroom
Solution Approach 1:
The patent applies dynamics by making the transformer turns ratio adjustable rather than fixed. The controller dynamically selects between different turns ratios (first and second turns ratios) based on operating conditions. When reactive power export is needed, the controller switches to the first turns ratio configuration which provides the necessary voltage boost without requiring excessive current, thereby reducing converter losses while maintaining reactive power capability.
Solution Approach 2:
The patent changes the electrical parameters of the transformer by providing at least two different turns ratios. This parameter change allows the system to optimize between voltage and current requirements. By switching between different turns ratio configurations, the system can achieve the required reactive power export capability while maintaining efficient operating conditions and minimizing losses.
2Power
If the maximum achievable PWM voltage is limited by technology or standards, then the nominal voltage selection is constrained, but this limits the reactive power provision capability
Solution Approach 1:
The patent introduces the transformer with adjustable turns ratios as an intermediary device between the power converter and the grid. This intermediary allows voltage transformation that enables the converter to operate within its maximum achievable PWM voltage limits while still providing the required reactive power to the grid. The transformer acts as a mediator that decouples the converter's voltage constraints from the grid's voltage requirements.
Solution Approach 2:
By making the transformer turns ratio dynamic and adjustable, the system gains adaptability to different operating conditions. The controller can select appropriate turns ratios based on the required reactive power level, enabling the system to adapt to varying grid requirements while respecting the converter's maximum PWM voltage capabilities defined by technology and standards.
3Adaptability or versatility
If the wind turbine power converter headroom is fixed, then the design is simplified, but it cannot easily adapt to changing reactive power range requirements
Solution Approach 1:
The patent implements dynamics by providing a controller that can switch between different transformer connections and turns ratios based on reactive power requirements. This dynamic reconfiguration capability allows the system to adapt to changing reactive power range requirements without requiring an oversized fixed-capacity converter, thereby achieving adaptability with moderate additional complexity in the control system.
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
This approach enables efficient dynamic control of reactive power, minimizing losses and enhancing voltage control capabilities within the power system, while allowing for flexible operation within defined reactive power ranges.
Implementation Method 1
a transformer connected between the at least one wind turbine and the power system
Implementation Method 2
connecting at least one passive device to the transformer
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Passive reactive compensation for a wind power plant It is provided a method of transmitting reactive power between a at least one wind turbine (10) and a power system (200) through a transformer (110) connected between the at least one wind turbine (10) and the power system (200), the wind turbine (10) including a power converter (20). The method includes a second step (302) of connecting at least one passive device (120, 130) to the transformer (110) and reducing or increasing a reactive power (194) of the power converter (20) of an amount corresponding to the reactive contribution from the passive device (120, 130).