Wind Farm Reactive Power Control Without Three-Winding Transformers
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Solution Overview
Problem
The use of three-winding transformers in wind turbines is costly, and eliminating them while maintaining the ability to control reactive power is challenging due to the absence of impedance between wind turbines, leading to difficulties in regulating turbine terminal voltage.
Innovation Solution
Implementing a system with cluster-level controllers to manage reactive power generation, eliminating the need for three-winding transformers by distributing reactive power commands across clusters of wind turbines, and utilizing partial power transformers and bi-directional power converters to regulate voltage and reactive power at the cluster level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-winding transformers are used in wind turbines, then reactive power control capability is maintained, but system cost increases
Solution Approach 1:
The patent extracts the reactive power control function from the three-winding transformer and relocates it to cluster-level controllers. This eliminates the need for expensive three-winding transformers at each turbine while maintaining reactive power control capability through centralized control of power converters in each cluster.
Solution Approach 2:
The power converters in the cluster are designed to perform multiple functions: active power generation, reactive power compensation, and voltage regulation. This multi-functionality replaces the specialized three-winding transformer, reducing component count and system cost while maintaining control capability.
2Device complexity
If three-winding transformers are eliminated, then system cost decreases, but voltage regulation capability deteriorates due to absence of impedance between turbines
Solution Approach 1:
The patent introduces cluster-level controllers as intermediaries that manage reactive power distribution among turbines in a cluster. These controllers provide the necessary impedance control function that was previously provided by three-winding transformers, enabling voltage regulation without direct transformer connections between turbines.
Solution Approach 2:
The wind farm is segmented into multiple clusters, each with its own controller. This segmentation allows decentralized voltage regulation at the cluster level, maintaining control capability while eliminating the need for centralized three-winding transformers at each turbine location.
3Productivity
If cluster-level control is implemented, then reactive power optimization is improved, but control system complexity increases
Solution Approach 1:
The patent merges the reactive power control functions of multiple turbines into a single cluster-level controller. This consolidation simplifies the overall control architecture by reducing the number of independent control systems while maintaining optimization capability through coordinated control of power converters within each cluster.
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 enhances power system reliability, reduces costs, increases efficiency, and allows for higher annual energy production while eliminating transient voltage stability issues.
Implementation Method 1
a bi-directional power converter 38 that includes a rotor-side converter 40 joined to a line-side converter 42 via a regulated DC link 44. The rotor-side converter 40 converts the AC power provided from the rotor 30 into DC power and provides the DC power to the DC link 44. The line side converter 42 converts the DC power on the DC link 44 into AC output power suitable for the power grid.
Implementation Method 2
The converter power path includes a partial power transformer
Implementation Method 3
The rotor blades 20 capture kinetic energy of wind using known airfoil principles. As wind impacts the rotor blades 20, the blades 20 transform wind energy into a mechanical rotational torque
Implementation Method 4
The high-speed shaft 26 is generally rotatably coupled to a generator 28 so as to rotatably drive a generator rotor 30. As such, a rotating magnetic field may be induced by the generator rotor 30 and a voltage may be induced within a generator stator 32
Data Source
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AI summary
A method for optimizing reactive power generation of an electrical power system includes generating, via a plurality of cluster-level controllers, a cluster-level reactive power command for each cluster of electrical power subsystems based on a system-level reactive power command. The method also includes determining, via the cluster-level controllers, a subsystem-level reactive power command for each of the electrical power subsystems based on the cluster-level reactive power command. Further, the method includes evaluating, via a plurality of subsystem-level controllers, reactive power capability of a plurality of reactive power sources within each of the electrical power subsystems. Moreover, the method includes generating, via each of the subsystem-level controllers, an actual reactive power for each of the electrical power subsystems based on the evaluation by allocating a portion of the subsystem-level reactive power command to each of the plurality of reactive power sources.