Wind Turbine Hydraulic Pitch Control Under Pressure Drop
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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 due to high flow rates or long travel distances.
Innovation Solution
A hydraulic system that includes a reservoir, a pump, and an accumulator, where the pump supplies fluid to the accumulator if pressure falls below a threshold, and the system determines and adjusts the target outflow to the pitch control cylinder, ensuring continuous operation by maintaining hydraulic fluid pressure within thresholds, even if the pressure drops below the lower threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump displacement is increased to secure the required inflow of hydraulic fluid, then the hydraulic fluid pressure can be maintained, but the device complexity and cost increase
Solution Approach 1:
The pump displacement is made variable rather than fixed, allowing the pump to adjust its displacement dynamically based on the actual hydraulic fluid consumption. This enables the pump to provide sufficient inflow during high consumption periods while maintaining simpler operation during normal conditions, thus maintaining pressure reliability without permanently increasing device complexity
Solution Approach 2:
The pump displacement parameter is changed from a fixed value to a variable parameter that can be adjusted based on system needs. By monitoring hydraulic fluid consumption and pressure levels, the control system adjusts the pump displacement to match actual requirements, avoiding the need for oversized pumps while ensuring pressure maintenance capability
2Reliability
If additional pumps are started from a pump array to increase inflow, then the hydraulic fluid pressure can be maintained, but the device complexity and operational control difficulty increase
Solution Approach 1:
Instead of using multiple fixed-displacement pumps that require complex coordination and control logic, a single variable-displacement pump is used that can dynamically adjust its output. This simplifies the pump array management by replacing multiple controllable units with one adaptable unit, maintaining pressure reliability without increasing operational control difficulty
3Reliability
If the accumulator is scaled-up to satisfy worst-case scenarios, then the hydraulic fluid pressure can be maintained during high consumption, but the device complexity and cost increase
Solution Approach 1:
The system implements feedback control by monitoring hydraulic fluid consumption rates and pressure levels in real-time. Based on this feedback, the pump displacement is adjusted to match actual demand, allowing a smaller accumulator to suffice since the pump can respond dynamically to high consumption scenarios rather than relying on a large accumulator to handle all worst-case situations
4Device complexity
If the pump flow is controlled exclusively by upper and lower pressure thresholds, then the control system is simple, but the hydraulic fluid pressure may drop below thresholds during high consumption, triggering safe mode
Solution Approach 1:
The control parameter for pump operation is changed from solely pressure-based (upper and lower thresholds) to include consumption rate-based control. By monitoring the rate of hydraulic fluid consumption and adjusting pump displacement accordingly, the system maintains pressure within thresholds during high consumption periods, ensuring continuous operation while keeping the control logic relatively simple through the use of a single pump
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 scaling up the accumulator, thereby reducing costs.
Implementation Method 1
at least one pump configured to supply the hydraulic fluid from the reservoir to at least one accumulator
Implementation Method 2
The accumulator is configured to store the pressurized hydraulic fluid supplied by the pump
Implementation Method 3
The pressurized hydraulic fluid in the pitch control cylinder drives at least one piston to change the pitch angle of the blade
Data Source
AI summary
Provided is 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 including 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.