Overspeed Prevention in Wind Turbines

Intelligent control for wind turbines to mitigate damage and improve power output in case of overspeed. The strategy involves predicting turbine loads and power using a model given the current state. Multiple control strategies are defined as shutdown, curtailment, or continue. The predicted loads and power for each strategy are compared. The one satisfying targets like load limits and max power are selected. This allows dynamically choosing the best response for an overspeed event instead of always shutting down.

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Controlling wind turbine operation to prevent overspeed and runaway in rapidly changing wind conditions. The method involves monitoring wind turbine parameters like generator speed and determining variance over short periods. If variance exceeds a threshold, indicating rapid wind changes, the turbine is curtailed to reduced speeds until variance decreases. This prevents overspeeding when the wind quickly shifts back.

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Wind turbine system with power split transmission coupling that enables efficient power generation and regeneration. The power split transmission coupling is a variable torque coupling that can divert hydraulic fluid to limit power to the generator when the rotor speed exceeds the generator's rating. The diverted fluid is stored under pressure. When the rotor speed drops below the generator rating, the stored fluid is used to boost generator power via a hydraulic motor. This allows generating the maximum potential power without exceeding the generator rating. The system can capture more power from varying wind speeds by using stored energy during lulls.

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Automatic emergency yaw control system for wind turbines to prevent overrun. It uses an emergency yaw control circuit that turns on the yaw braking circuit when turbine speed exceeds rated, then yaw drive after delay. This causes the turbine to yaw out of the wind to reduce speed. If yaw power is lost, backup power is provided to still yaw.

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Wind turbine braking system that provides accurate and adaptive braking control under different wind conditions. The system uses a power module, high-speed shaft brake module, and hydraulic locking pin module. It determines the optimal braking strategy based on the impeller speed. For fast speeds, it uses low-pressure braking. For slower speeds, it uses high-pressure braking. This improves adaptation and prevents over-braking. It also protects the locking pin by using low-pressure supply first, then high-pressure if needed.

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Wind turbine torque control method to quickly accelerate or decelerate the blade shaft when the wind speed changes between cut-in and rated speeds. The method involves determining if the blade shaft has an acceleration or deceleration trend based on real-time wind speed and blade shaft speed. If so, it calculates the optimal blade shaft speed and determines the blade shaft control torque to accelerate or decelerate the blades. This allows faster response to wind speed changes compared to traditional torque control methods.

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Preventing wind turbines from overspeeding during power outages by using a passive electromagnetic brake. The brake is connected to the pitch controller and an overspeed switch. When power is off, the brake is in the released state. If the pitch controller fails or the power grid goes down, the overspeed switch detects overspeed and activates the brake to prevent the turbine from overshooting. This provides backup braking to avoid overrun in case of power loss.

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A method to prevent wind turbines from getting stuck in an out-of-control state when the braking system fails. The method involves remotely restarting the turbine from a shutdown state to a standby state where the blades can feather. This is done by modifying the turbine's state machine when it is detected in shutdown. This prevents overspeeding and tower collapse when the turbine loses braking control.

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Wind turbine overspeed protection method that provides alternative means to stop the turbine if the primary protection fails. The method involves three steps: normal shutdown, torque control, and emergency yaw. If the main overspeed protection fails, the turbine initiates this auxiliary protection. First, it retracts and shuts down the blades using main power. Next, it increases the load torque using converter control to brake the turbine. Finally, it forces the turbine to yaw into crosswind using emergency power to further slow it down.

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Active braking system for wind turbines that allows controlled slowing of the rotor speed without separate brakes when wind speeds exceed safe operation limits. The system uses a two-section main shaft with a clutch between sections. At low wind speeds, the clutch connects the sections and power is transmitted directly. At high wind speeds, the clutch disconnects and the sections decouple. An active braking mechanism converts the rotation of the second section into linear motion to brake it. This reduces the overall shaft rotation. If speeds are still too high, mechanical brakes engage. The active braking allows controlled slowing without full braking when wind speeds exceed safe limits.

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A wind turbine controller that reduces rotor speed, like to a stop, during rapid wind direction changes to mitigate loadings and vibrations. The controller provides two shutdown modes. In the first mode, it gradually reduces generator torque and blade pitch to zero. In the second mode, it provides higher torque and faster blade pitch changes to quickly stop the rotor. The second mode exceeds torque limits and pitches blades fully to prevent negative thrust forces. This allows faster shutdowns during severe wind direction changes.

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Emergency yaw control system for wind turbines to prevent overspeeding and reduce risk of component failure when the pitch control system breaks down. The system starts emergency yawing when the rotor speed exceeds rated, using a contactor. A delay relay times the yawing and a first relay stops it. This prevents high wind speeds from causing vibrations. A second relay resets the yaw residual pressure valve after yawing stops.

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Identifying and protecting against complicated wind conditions to improve wind turbine safety and performance. The method involves analyzing wind resource and turbine operation data to identify instances of extreme gusts, wind direction changes, abnormal speed increases, or pitch changes that may indicate complex wind conditions. If the proportion of time with these conditions exceeds a threshold, the turbine is controlled to take protective actions like limiting power, pitch, or shutting down.

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A wind turbine control system reduces unnecessary shutdowns due to flutter by dynamically setting overspeed thresholds based on flutter speed and blade pitch, rather than using fixed thresholds. This allows operating closer to flutter limits without risking actual flutter. The system determines flutter speed based on pitch and wind speed inputs. It then sets an overspeed threshold below flutter speed. This prevents false positives from fixed thresholds while avoiding flutter. The system can use a lookup table to map pitch, wind speed, and existing thresholds to determine the final threshold.

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Avoiding wind turbine operation in a speed range prone to resonance to prevent vibration and damage. The method involves monitoring how often the generator speed enters the avoidance range. If it occurs too frequently, parameters like pitch angle and torque are adjusted to stabilize the speed control and keep it away from the problematic range. This avoids safety issues like resonant vibration and overloading.

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A method to prevent wind turbines from repeatedly operating in a rotational speed avoidance range that can cause vibration and load issues. The method involves monitoring the turbine to see if the generator speed frequently enters the avoidance range. If so, pitch control and torque control parameters are adjusted to keep the speed stable and avoid issues.

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Method and apparatus for improving rotational speed avoidance control in wind turbines to prevent issues like excessive vibration and overloading. The method involves identifying if the turbine repeatedly traverses the rotational speed avoidance range, where it's prone to resonance and problems. This is done by analyzing historical turbine data for metrics like the number of times the speed enters the range or the duration spent there. If excessive, parameters of the pitch control and torque control systems are adjusted to avoid staying in the range. This prevents issues like prolonged resonance and impacts.

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Controlling the yaw of a wind turbine to avoid overspeeding of the yaw drive motors. The method involves using a virtual master drive to balance the motor loads and prevent overspeeding. The virtual master drive calculates a mean motor speed reference based on all the motor speeds. If a motor speed exceeds a threshold, its torque is reduced to avoid overspeeding. The torque of the remaining motors is increased to compensate and maintain overall nacelle rotation. This allows the yaw system to coordinate and balance the motor speeds to avoid overspeeding.

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Operating wind turbines to avoid overloading the low voltage winding of the main transformer. If the sum of the generator rotor current and load current exceeds the transformer's current limit, it provides reduced current to the rotor and load when the turbine is sub-synchronous (below rated speed). This prevents exceeding the transformer's limit while still allowing full power output.

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Wind turbine drive system that can balance loads across multiple pitch and yaw drive units to prolong their life. The system uses load sensors on each drive unit to detect the load on the ring gear. A controller then adjusts the braking force of each drive unit to equalize the loads. This reduces the variation in load applied to each drive unit and prevents overloading of any one unit.

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