Wind Plant Capacitor Control for Reactive Power Transients
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Solution Overview
Problem
Wind power plants face challenges in meeting grid connection requirements for voltage regulation due to communication delays and limitations in reactive power compensation, particularly when wind turbines alone cannot fulfill the necessary reactive power demands, leading to the need for additional equipment like static compensators and mechanical switching capacitors/reactors.
Innovation Solution
A method for controlling capacitors or reactors in wind power plants that involves calculating reactive power needs and strategically connecting/disconnecting passive devices to minimize transients, using a centralized controller to allocate reactive power references to wind turbine generators and STATCOMs, and employing switchable capacitor banks to maintain reactive power within operational limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wind turbines alone are used for reactive power compensation, then device complexity is minimized, but reactive power compensation capability is insufficient to meet grid code requirements
Solution Approach 1:
The patent combines wind turbine reactive power capability with switchable capacitor banks and reactors to create a hybrid reactive power compensation system. This merging allows the system to meet grid code requirements while avoiding the need for expensive static compensators, thus resolving the contradiction between device complexity and voltage regulation capability.
2Reliability
If mechanical switching capacitors/reactors are added for steady state performance, then voltage regulation capability is improved, but device complexity and switching operations increase
Solution Approach 1:
The patent implements a dynamic control strategy that adjusts capacitor bank switching decisions based on real-time system conditions including transient state detection. The controller monitors reactive power requirements and voltage levels, dynamically determining when switching is necessary versus when wind turbine adjustment alone suffices, thereby reducing unnecessary switching operations and device complexity.
3Device complexity
If communication delays of hundreds of milliseconds are present, then coordination between plant control and turbine control is simplified, but voltage regulation response time deteriorates
Solution Approach 1:
The patent segments the voltage regulation function into two independent control loops: a fast inner loop at turbine level for reactive power control, and a slower outer loop at plant level for voltage control. This segmentation allows each loop to operate independently without being constrained by communication delays between levels, resolving the contradiction between coordination simplicity and response speed.
4Manufacturing precision
If excessive switching operations are performed to maintain voltage regulation, then voltage control precision is improved, but energy losses and device wear increase
Solution Approach 1:
The patent implements a transient state detection mechanism that identifies when full capacitor bank switching is necessary versus when partial adjustment through wind turbine reactive power modulation suffices. By applying partial action (turbine adjustment) instead of excessive action (full switching) when appropriate, the system maintains voltage control precision while minimizing switching operations and associated energy losses.
Data Source
AI summary
The present invention relates to a control system and an associated method for controlling an amount of reactive power delivered from a wind power plant to an associated power supply grid, the control system comprising a wind power plant controller and a number of wind turbine controllers each being in communication with said wind power plant controller, wherein the wind power plant controller is adapted to provide a grid voltage reference in response to a required total amount of reactive power to at least one wind turbine controller and operating a Switched Capacitor bank.