Wind Turbine Ride-Through Control for Stable Grid Voltage Recovery
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Solution Overview
Problem
Existing wind turbine technologies lack effective methods for transitioning between high voltage ride-through and low voltage ride-through states, leading to inadequate active and reactive power support during voltage changes, which can result in grid voltage instability.
Innovation Solution
A method and system for controlling a permanent magnet direct-driven wind turbine to provide a gradually increasing active current and reactive current during the transition from high voltage ride-through to low voltage ride-through, with the reactive current adjusted based on the turbine's operation state before the high voltage ride-through, ensuring accurate reactive power support to the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only transient reactive power support is provided during voltage ride-through, then the control method is simple, but the grid voltage stability is insufficient during transition from high voltage ride-through to low voltage ride-through
Solution Approach 1:
The patent implements dynamic control by dividing the voltage ride-through process into distinct stages (high voltage ride-through, transition, and low voltage ride-through), with different active and reactive power control strategies for each stage. The control parameters are dynamically adjusted based on the current operating phase and grid voltage conditions, enabling adaptive response to changing grid conditions while maintaining systematic control structure.
Solution Approach 2:
The patent segments the voltage ride-through process into multiple distinct phases: high voltage ride-through state, transition state, and low voltage ride-through state. Each phase has specific control objectives and strategies, allowing the system to provide appropriate active and reactive power support for each stage, thereby improving overall grid voltage stability without requiring overly complex unified control.
2Speed
If active power is rapidly restored during transition from high voltage ride-through to low voltage ride-through, then the power recovery speed is high, but the grid voltage becomes unstable due to excessive active power increase
Solution Approach 1:
The patent implements dynamic control by dividing the voltage ride-through process into distinct stages (high voltage ride-through, transition, and low voltage ride-through), with different active and reactive power control strategies for each stage. The control parameters are dynamically adjusted based on the current operating phase and grid voltage conditions, enabling adaptive response to changing grid conditions while maintaining systematic control structure.
Solution Approach 2:
The patent applies preliminary action by establishing a planned transition strategy before the actual transition occurs. The control system pre-defines the active and reactive power adjustment rates for the transition phase, ensuring that when transition from high voltage ride-through to low voltage ride-through occurs, the power restoration follows a predetermined safe trajectory that maintains grid voltage stability.
3Reliability
If reactive current is not adjusted according to pre-ride-through operation state, then the control is simpler, but the reactive power support is insufficient or excessive leading to voltage instability
Solution Approach 1:
The patent implements feedback control by monitoring the wind turbine's operation state before high voltage ride-through (such as whether it was providing capacitive, inductive, or zero reactive power) and using this information to determine the appropriate reactive current during the transition phase. This feedback mechanism ensures that the reactive power support is accurately matched to the actual grid needs and turbine state, preventing both insufficient and excessive reactive power injection.
Solution Approach 2:
The patent applies local quality by tailoring the reactive current control strategy to the specific pre-ride-through operation state of the wind turbine. Different reactive current adjustment strategies are applied depending on whether the turbine was previously providing capacitive reactive power, inductive reactive power, or zero reactive power, ensuring that the control is optimally adapted to the local operating conditions.
Data Source
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AI summary
The present application provides a method and a system for controlling continuous high voltage ride-through and low voltage ride-through of a permanent magnet direct-driven wind turbine. The method includes: determining a transient time period during which the wind turbine is transitioned from a high voltage ride-through state to a low voltage ride-through state; controlling the wind turbine to provide, during the transient time period, a gradually increasing active current to the point of common coupling; and controlling the wind turbine to provide, during the transient time period, a reactive current to the point of common coupling according to an operation state of the wind turbine before the high voltage ride-through state. According to the embodiments of the present application, voltage of a power grid can be effectively supported.