As a key component of the pitch control system, the pitch servo valve plays a vital role in the wind power generation system. It not only directly affects the operating efficiency of wind turbines, but also concerns the safety and stability of wind turbines. In this paper, the function of pitch control system, the working principle of servo valve and its application and optimization in wind power system will be described in detail.
First, the basic function of pitch control system
The pitch system of wind turbine is mainly used to adjust the windward angle (i.e. pitch angle) of blades, so as to control the speed and output power of the wind turbine. When the wind speed changes, the wind turbine can be kept running stably at rated power by adjusting the pitch angle to avoid overload or shutdown. At the same time, in the case of emergency stop or low wind speed, the pitch control system can also turn the blades to the downwind direction to ensure the safety of the unit.
Second, the working principle of pitch servo valve
Servo valve is the core component of hydraulic servo control system, and its main function is to accurately adjust the flow and direction of hydraulic oil according to the control signal, so as to control the action of the actuator (such as hydraulic cylinder) and realize the accurate control of blade angle.
In the wind power pitch control system, servo valve, proportional amplifier and position sensor usually form a closed-loop control system. The controller calculates the required pitch angle according to the parameters such as wind speed, generator speed and power feedback, and sends the control signal to the servo valve. The servo valve adjusts the flow direction and flow rate of hydraulic oil according to the signal, and drives the hydraulic cylinder to push the blade to rotate to the target angle. The position sensor feeds back the blade angle in real time to realize closed-loop adjustment, ensuring fast response and high control accuracy.
Third, the application characteristics of servo valve in wind power
1. High reliability requirements: Because wind turbines are usually installed in remote areas or even at sea, the maintenance cost is high, so the servo valve must have high reliability and long service life.
2. High-precision control: pitch control requires the change of pitch angle to be extremely accurate to maintain the stability of power output, and the servo valve should have good linearity and response characteristics.
3. Strong anti-pollution ability: The hydraulic system is easy to be polluted by particulate matter during operation, which affects the performance of the servo valve, so the modern wind power servo valve mostly adopts anti-pollution design structure.
4. Strong high and low temperature resistance: it is suitable for stable operation under extreme weather conditions, and it is also one of the important performance indexes of wind power servo valve.
Fourth, the trend of technology development and optimization
With the development of large-scale and intelligent wind power industry, the traditional hydraulic pitch control system gradually transits to electric pitch control system, but hydraulic pitch control is still widely used in high-power wind turbines because of its advantages of fast response and large torque. As the core of hydraulic pitch control system, servo valve is constantly upgrading. For example, adopting digital servo valve, integrating pressure and flow control module, applying new materials and sealing structure are all the directions of current technology development.
In addition, in the aspect of intelligence, the servo valve has also begun to integrate the state monitoring function, collecting working parameters in real time through sensors, providing data support for predictive maintenance and improving the overall operation and maintenance efficiency of wind turbines.
V. Conclusion
To sum up, as the heart component of the hydraulic pitch control system of wind power, the performance of pitch control servo valve is directly related to the operation efficiency, safety and stability of the whole wind turbine. With the continuous progress of technology, servo valves are developing in the direction of high precision, high reliability and intelligence, providing solid technical support for the development of wind power industry. In the future, with the further improvement of efficiency and safety requirements of wind power system, the innovation and development of servo valves will continue to promote the technological upgrading of the whole industry.