Wind Turbine Pitch Hydraulics With Pump-Accumulator Delay Bridging
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Solution Overview
Problem
Existing hydraulic systems for wind turbine rotor blade pitch angle adjustment suffer from inefficiencies due to the exclusive use of hydraulic accumulators, which require large and expensive rotary feedthroughs, generate excessive heat, and are complex to maintain, while variable displacement pumps are not suitable for direct control without significant delay.
Innovation Solution
A hydraulic system incorporating a variable displacement pump, hydraulic accumulator, control valve, and dynamic valve, arranged without rotary feedthroughs, allowing efficient pressure application and reduced heat generation, with a control unit managing the system to bridge the delay in quantity provided by the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed displacement pump is used to charge the hydraulic accumulator, then the accumulator can be charged with pressure, but rotary feedthroughs are required which are expensive, complex and maintenance-intensive
Solution Approach 1:
The invention extracts the pump from the rotating hub and relocates it to the stationary nacelle, eliminating the need for rotary feedthroughs. The pump is now positioned where it can charge the accumulator without requiring rotationally sealed connections.
Solution Approach 2:
The invention introduces a hydraulic line as an intermediary medium to transfer hydraulic fluid from the stationary pump in the nacelle to the rotating accumulator in the hub, replacing the need for direct rotary feedthrough connections.
2Power
If a fixed displacement pump is used, then the accumulator can be charged, but excessive heat is generated
Solution Approach 1:
The invention changes the operating parameters of the pump by using a variable displacement pump instead of a fixed displacement pump, allowing the pump to adjust its output to match actual system needs and reduce unnecessary energy conversion to heat.
Solution Approach 2:
The invention makes the pump displacement variable rather than fixed, allowing dynamic adjustment of the pump output based on system requirements, thereby reducing energy waste and heat generation during operation.
3Speed
If a variable displacement pump is used for direct control of the pitch cylinder, then response time is improved, but the pump requires significant delay after swinging out to provide desired quantity or pressure
Solution Approach 1:
The invention uses the hydraulic accumulator as a pre-charged energy reservoir that can immediately supply hydraulic fluid to the pitch cylinder when needed, eliminating the pump response delay. The pump only needs to recharge the accumulator at its own pace.
Solution Approach 2:
The hydraulic accumulator serves as a cushion or buffer that is pre-filled with hydraulic fluid under pressure, ready to provide immediate response for pitch adjustments without waiting for the pump to deliver fluid.
4Quantity of substance
If a large hydraulic accumulator is selected to provide necessary pressure and quantity, then the pitch cylinder can be supplied with sufficient pressure, but the system becomes more complex and expensive
Solution Approach 1:
The invention maintains continuous pressure supply to the pitch cylinder by having the variable displacement pump continuously recharge the hydraulic accumulator, ensuring the accumulator always contains sufficient pressurized fluid without needing to be oversized.
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
The system reduces heat generation, eliminates the need for rotary feedthroughs, and enables a smaller, more cost-effective accumulator, providing precise pressure application as needed, enhancing efficiency and reducing maintenance complexity.
Implementation Method 1
a variable displacement pump (12), a hydraulic accumulator (14), a dynamic valve (16), a control valve (18)
Implementation Method 2
The hydraulic accumulator and the dynamic valve are provided to bridge the design-related delay in the quantity provided by the variable displacement pump
Implementation Method 3
The control valve is preferably configured as a proportional valve, preferably as a spool valve
Implementation Method 4
The pitch cylinder is supplied with pressure via a hydraulic accumulator, whereby the hydraulic accumulator can be charged via a suitable and simply constructed unit arranged in the nacelle
Data Source
AI summary
A hydraulic system for the pitch angle adjustment of a rotor blade of a wind turbine) includes a variable displacement pump, a hydraulic accumulator, a dynamic valve, a control valve, a tank and a pitch cylinder. The variable displacement pump is connected to the control valve via a first connecting line and the control valve is connected to the tank via a second connecting line and to a piston side of the pitch cylinder via a third connecting line and to a rod side of the pitch cylinder via a fourth connecting line. In a first switching position, the first connecting line is connected to the third connecting line and in a second switching position, the first connecting line is connected to the fourth connecting line and the second connecting line is connected to the third connecting line.