Wind Farm Reactive Power Control with Cluster-Level VAR Coordination
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Solution Overview
Problem
The management of reactive power in wind farms is complicated by the absence of impedance provided by three-winding transformers, making it difficult for wind turbines to regulate terminal voltage effectively, leading to reactive power oscillations and increased costs due to expensive transformer components.
Innovation Solution
Implementing a system with cluster-level controllers that receive reactive power commands from a system-level controller, generating cluster-level reactive current commands, and distributing them to turbine-level controllers, using a two-winding transformer configuration that eliminates the need for three-winding transformers and stabilizes voltage/VAR control at the cluster level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-winding transformers are used in wind turbine power systems, then voltage regulation capability is improved, but system cost and complexity increase
Solution Approach 1:
The patent divides the wind farm into multiple clusters, each with its own cluster-level controller. This segmentation allows distributed reactive power control at the cluster level, eliminating the need for complex three-winding transformers at each turbine while maintaining voltage regulation capability through coordinated cluster-level control.
Solution Approach 2:
The patent introduces cluster-level controllers as intermediary devices between individual turbines and the central system-level controller. These cluster-level controllers manage reactive power distribution within their clusters, providing the necessary voltage regulation function without requiring complex three-winding transformer configurations at each turbine.
2Reliability
If three-winding transformers are used for voltage regulation, then terminal voltage control is improved, but reactive power oscillations occur
Solution Approach 1:
The patent implements dynamic reactive power control at the cluster level, where cluster-level controllers continuously adjust reactive power commands based on real-time system conditions. This dynamic control approach prevents reactive power oscillations by coordinating the reactive power output of multiple turbines within each cluster, maintaining terminal voltage control without the instability issues associated with individual turbine control using three-winding transformers.
3Adaptability or versatility
If three-winding transformers are used in each wind turbine, then power conversion capability is improved, but system cost increases
Solution Approach 1:
The patent merges the transformer function to the cluster level rather than having individual three-winding transformers at each turbine. By combining multiple turbine outputs at the cluster level and using cluster-level controllers to manage reactive power, the system achieves the necessary power conversion capability while significantly reducing the quantity and cost of transformers required.
Solution Approach 2:
The cluster-level controllers perform multiple functions including reactive power management, voltage regulation, and coordination with the system-level controller. This multi-functionality eliminates the need for complex three-winding transformers at each turbine, as the cluster-level infrastructure provides the necessary power conversion and voltage regulation capabilities for the entire cluster.
4Ease of operation
If distributed reactive power control is implemented without cluster-level coordination, then individual turbine control is simplified, but voltage oscillations occur
Solution Approach 1:
The patent implements a hierarchical feedback control system where cluster-level controllers receive reactive power commands from the system-level controller and provide feedback on cluster performance. This feedback mechanism enables coordinated control across clusters, maintaining voltage stability while allowing individual turbines to operate with simplified control logic by following cluster-level directives rather than requiring complex autonomous control.
Data Source
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AI summary
A method for reactive power control of a wind farm having a plurality of clusters of wind turbines with a cluster transformer connecting each cluster of wind turbines to a power grid is provided. The method includes receiving, via a plurality of cluster-level controllers, a reactive power command from a farm-level controller. The method also includes generating, via the cluster-level controllers, a cluster-level reactive current command for each cluster of wind turbines based on the reactive power command. Further, the method includes distributing, via the cluster-level controllers, a turbine-level reactive current command to turbine-level controllers of the wind turbines based on the cluster-level reactive current command.