Wind Turbine Blade Pitch Hydraulics for Accumulator Pressure Stability
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Solution Overview
Problem
In wind turbine pitch control systems, high fluid consumption can lead to hydraulic fluid pressure drops, triggering a safe mode and potentially causing wind turbine shutdown, especially when pumps are of fixed-displacement type or when fluid consumption is high.
Innovation Solution
A method and hydraulic system that determines a target outflow of pressurized hydraulic fluid to the pitch control cylinder and adjusts the pump displacement or number of pumps to meet this demand, ensuring continuous operation by maintaining hydraulic fluid pressure within thresholds, even below the lower threshold, using a variable or fixed-displacement pump configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump displacement is increased to meet high fluid consumption, then the hydraulic fluid pressure can be maintained, but the system complexity and energy consumption increase
Solution Approach 1:
The patent employs a variable-displacement pump that dynamically adjusts its pump rate based on real-time comparison between target outflow and predicted inflow to the accumulator. This dynamic adjustment allows the system to maintain hydraulic pressure without requiring oversized accumulators or complex pump arrays, resolving the contradiction between reliability and device complexity
Solution Approach 2:
The control device continuously monitors the hydraulic fluid pressure in the accumulator and adjusts the pump rate accordingly by comparing target outflow with predicted inflow. This feedback mechanism ensures pressure maintenance while optimizing pump operation, avoiding the need for increased system complexity
2Reliability
If oversized accumulators are used to prevent pressure drops, then the risk of safe mode triggering is reduced, but the system cost increases
Solution Approach 1:
Instead of using oversized accumulators to statically guarantee pressure maintenance, the patent uses a dynamically adjustable pump rate that adapts to actual fluid consumption patterns. The control device calculates the difference between target outflow and predicted inflow, adjusting pump operation in real-time to prevent pressure drops without requiring excessive accumulator capacity
Solution Approach 2:
The system changes the operational parameters of the pump (pump rate) based on real-time conditions rather than relying on fixed accumulator sizing. By monitoring hydraulic fluid pressure and adjusting pump rate dynamically, the system achieves safe mode prevention with optimally sized accumulators, reducing overall system cost
3Device complexity
If fixed-displacement pumps are used, then the system simplicity is maintained, but the ability to meet variable fluid demand is limited
Solution Approach 1:
The patent transitions from fixed-displacement to variable-displacement pumps that can dynamically adjust their output. The control device modulates the pump rate based on the difference between target outflow and predicted inflow, enabling the system to adapt to varying fluid demands while maintaining pressure within thresholds, thus resolving the contradiction between simplicity and adaptability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the risk of safe mode triggering, allowing continuous wind turbine operation and increased electricity production without the need for oversized accumulators, thereby reducing costs.
Implementation Method 1
The pressurized hydraulic fluid in the pitch control cylinder drives a piston to change the pitch angle of the blade
Implementation Method 2
at least one pump configured to supply the hydraulic fluid from the reservoir to at least one accumulator
Implementation Method 3
The accumulator is configured to store the pressurized hydraulic fluid supplied by the pump and to supply the pressurized hydraulic fluid to at least one pitch control cylinder
Data Source
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AI summary
It is described a method of controlling a pitch angle of at least one blade of a wind turbine by use of a hydraulic system, the hydraulic system comprising at least one reservoir configured to store a hydraulic fluid, and at least one pump configured to supply the hydraulic fluid from the reservoir to at least one accumulator, if a hydraulic fluid pressure in the accumulator falls below a lower threshold value and till the hydraulic fluid pressure in the accumulator exceeds an upper threshold value. The accumulator is configured to store the pressurized hydraulic fluid supplied by the pump and to supply the pressurized hydraulic fluid to at least one pitch control cylinder of the hydraulic system via at least one output valve of the hydraulic system. The pressurized hydraulic fluid in the pitch control cylinder drives at least one piston to change the pitch angle of the blade. The method comprises steps of determining a target outflow of the pressurized hydraulic fluid from the accumulator to the pitch control cylinder; determining a difference between the determined target outflow of the pressurized hydraulic fluid from the accumulator to the pitch control cylinder and a predetermined inflow of the hydraulic fluid from the reservoir to the accumulator; and supplying the hydraulic fluid from the reservoir to the accumulator by the pump regardless whether or not the hydraulic fluid pressure in the accumulator is fallen below the lower threshold value, if the determined target outflow is larger than the predetermined inflow.