Overspeeding Control Techniques for 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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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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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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Method to control the pitch angle of wind turbine blades to prevent overspeeding the rotor when the turbine is operating off-grid in a standby mode. The method compares the actual rotor speed with the target speed and applies a modified error value to the pitch control system. The modification factor is increased if the actual speed is beyond a certain range. This allows the blades to be pitched to regulate the speed even without grid power.

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Dynamic rotational speed control system for wind turbines that protects the turbine from unstable conditions. The system has a rotating stop assembly that limits the airfoil pitch angle. When the turbine exceeds a safe speed, centrifugal force makes the stop rotate and reduce the pitch angle. This decreases power output and slows the turbine back down. The stop only engages at high speeds to avoid reducing power when it's needed.

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Control system for wind turbines to protect against damage during anomalies by leveraging higher torque limits. When an abnormal event like overspeeding or blade failure occurs, the system enters an enhanced braking mode where the generator is operated with maximum available torque exceeding nominal limits. This accelerates rotor deceleration to reduce damage. Actual operating limits of electrical components are determined and used to set the enhanced torque level. This prevents damage while maximizing braking force.

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Fail-safe emergency shutdown system for wind turbines to enable safe shutdown of wind turbines during emergencies. The system provides independent control of the blade pitch motion during an emergency to reduce structural loading and prevent rotor overspeed. It uses redundant valves and sensors to detect emergencies and rotor acceleration. These signals open valves to allow hydraulic fluid flow at different rates through restriction nozzles to control pitch speed.

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Wind turbine control to improve frequency stability of power grids during frequency disturbance events. The method involves dynamically adjusting the power reference of the wind turbine to overproduce power when the grid frequency changes. This transfers kinetic energy from the turbine to stabilize the grid frequency. The overproduction is triggered by a change in grid frequency and uses an adaptive gain function tied to the frequency difference. The gain decreases with the turbine rotor speed to avoid excessive power release. The grid frequency is then regulated back to nominal levels using other generators.

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Controlling a wind turbine to improve performance by adapting operation in response to real-time measurements of turbulence and wind shear. The method involves measuring turbulence intensity and wind shear. Then operating the turbine in the partial load range at an operating point that differs from the point with maximum power, and setting the distance from the max power point according to turbulence intensity.

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Method for operating an electric machine like a wind turbine stably and optimally while avoiding overloading. The technique uses a dynamic capacity curve that continuously shifts towards a maximum allowed level based on evaluated active damping and stability criteria. This allows the machine to produce more power at low speeds where static limits are overly conservative while preventing instability or overheating at higher speeds. The dynamic curve balances power production with machine health by using damping as a measure of safe operation.

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Partial load control of wind turbines to enable operation at higher power ratings than the generator's nominal rating. The method involves monitoring the generator current and adjusting the turbine operation to balance the rotor-stator current levels. If approaching the rotor or stator current limits, the turbine controller modifies parameters like blade pitch or torque to slow or speed up the generator and shift the current balance. This prevents exceeding the current limits and allows operating at higher power ratings.

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A control system to prevent wind turbines from running away and potentially causing failures and accidents if the brake system fails. The system detects brake failure and initiates a controlled shutdown procedure. After brake failure, it calculates an initial crosswind nacelle position based on current wind direction. The yaw system then moves the nacelle to that position, reducing captured wind energy and rotor speed. If the wind direction suddenly changes during crosswind yawing, it recalculates a new crosswind position to avoid overshooting. The system also prevents conflicting yaw commands during the controlled shutdown.

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Method to limit power consumption when adjusting wind turbine rotor blades. The method adjusts rotor blades while taking into account their moment of inertia. This allows the acceleration of the blades to be limited based on their current deflection, wind speed, and other parameters. By not over-accelerating blades, power consumption and strain on the adjustment mechanism can be reduced.

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