With the gradual depletion of conventional energy such as coal and oil, mankind is paying more and more attention to the development and utilization of new energy (non-conventional energy). New energy refers to a variety of energy sources outside the traditional energy, such as solar energy, geothermal energy, wind energy, ocean energy, biomass and nuclear fusion energy. Which wind energy with its unique advantages and favored. Compared with other new energy sources, wind energy has three major advantages: first, large reserves, widely distributed; second, the availability of strong, relatively low cost; third, green energy, do not pollute the environment.
As a clean energy source using wind energy, wind power is playing an increasingly important role in today's increasingly important environmental protection. In recent years, the global wind energy market to more than 40% annual rate of rapid development, and China also by virtue of the rich wind resources and government support for new energy development, Europe and the United States after the world's most important wind energy market, which China wind Equipment manufacturing industry has brought development opportunities. China's wind energy is rich in resources, the theoretical reserves of 1.6 billion kilowatts, the actual utilization of 250 million kilowatts, with great potential for development. At the same time in the country's new energy development plan, the wind power as a key support industry, so that China's wind power industry has a broader development prospects.
So wind power has maintained a doubling in recent years, in 2008 the growth rate of wind turbines affected by GDP, but also more than 80%, the localization rate has more than 70%. Wind energy industry in order to healthy and sustained growth, we must complete the industrial system construction, industrial chain construction. Yike company seized the opportunity to develop a timely response to the needs of the product line and solutions, and was successfully applied to a number of wind farms.
Second, the horizontal axis of the wind turbine composition
Based on the higher efficiency of wind energy acquisition and utilization, the current wind power industry mainly uses horizontal axis wind turbine, its composition as shown on the right:
Rotor blade: capture wind energy and convert it to the rotational energy of the shaft;
Shaft: the kinetic energy of the rotating energy into the generator;
Gearbox: used to increase the rotor center and the shaft speed between the generator;
Generator: the use of rotating shaft rotation energy, through the electromagnetic principle of power generation;
Yaw controller (not shown): move the rotor to keep it in line with the wind direction;
Brake device: in the event of power overload or system failure to stop the rotation of the shaft;
Tower: support the rotor and the engine box, and the entire device location upgrade;
Third, the wind power control system
Wind power generation system as the core of the field of wind power generation, its technological innovation is essential. At present, the main use of constant speed constant frequency and variable speed constant frequency wind turbine system two categories. In wind power generation, when the wind turbine and the grid connected to the grid, the frequency of wind power and the frequency of the grid to maintain the same, that is, constant frequency. Constant speed constant frequency that is in the wind power generation process, to maintain the speed of the windmill (that is, the generator speed) unchanged, resulting in constant frequency of electricity. In the wind power generation process so that the speed of the windmill changes with the wind speed, and through other control methods to get constant frequency power method known as variable speed constant frequency.
As the wind and wind speed is proportional to the third power, when the wind speed in a certain range changes, if the windmill to allow variable speed movement, can achieve better use of wind energy purposes. The efficiency of the windmill's conversion of wind energy into mechanical energy can be expressed by the output power coefficient CP, where the CP reaches a maximum at a certain ratio of the wheel speed ratio λ (ratio of blade tip speed to wind speed). Constant speed constant frequency unit windmill speed remains unchanged, and wind speed is often changing, it is clear that CP can not remain at the best value. Variable speed constant frequency unit is characterized by windmill and generator speed can be changed in a wide range without affecting the output power frequency. As the speed of the windmill variable, can be properly controlled, so that the wind speed ratio or near the optimal value, so as to maximize the use of wind power. Therefore, the variable speed constant frequency wind power generation system with its high wind energy utilization factor, can absorb the wind caused by sudden changes in the energy fluctuations in order to avoid the spindle and transmission institutions to withstand excessive torque and stress, and can improve the system power factor and other prominent advantages in The wind power industry is becoming more and more popular.
Variable speed constant frequency control function is to ensure the quality of the Internet power, it must be measured on the generator speed and feedback to the controller to achieve closed-loop control. At present, the detection of generator speed is mainly used rotary encoder. At the same time because the generator power, will produce shaft current, if the encoder and the generator is not insulated, the shaft current will be introduced into the encoder, and then damage the encoder. Yike's EV88P series encoders use a unique mechanical design concept to ensure that the product's anti-vibration impact resistance, the use of advanced European electrical design technology to ensure that products in the -40 ~ 85 ℃ temperature conditions, reliable output, while the use of advanced Of the insulation treatment technology, effectively prevent the shaft current damage to the encoder. EV88P series of encoders, with its excellent performance characteristics and stable operation, has been a wind power equipment factory in North China has been successfully applied in the stable operation of the wind field has been recognized by customers.
Fourth, the variable pitch control system of wind power generation
In the development of wind power technology, wind turbine single capacity towards large-scale development, megawatt-class wind turbine has become the mainstream of wind power market products. At present, large-scale wind turbine generators use variable pitch control technology. Variable pitch control is controlled by rotating the blade along the longitudinal axis of the blade, adjusting the pitch angle at any time according to the change of the wind speed, controlling the energy absorption of the wind wheel and keeping the output power at a certain level. The advantage of variable pitch control is to ensure that the rated power of the high wind speed section is stable above the rated power point and has a high wind energy utilization factor at the rated point to improve the starting performance and braking performance of the wind turbine and improve the overall flexibility of the fan , Reduce the machine and the blade of the force situation. In the process of grid connection, pitch control can also achieve fast and no impact and network. Variable pitch control system and variable speed constant frequency technology to match, and ultimately improve the entire wind power generation system power generation efficiency and power quality.
There are two main actuators of the pitch control system, the hydraulic pitch actuator and the electric pitch actuator. Among them, the motor pitch actuator is the use of motor control of the blade, compact, flexible control, reliable action, there is no hydraulic actuator in the non-linear, oil, jam and other phenomena. The motor pitch control mechanism can be individually adjusted for each paddle using a servo motor. The servo motor controls the pitch angle of the blade directly by engaging the drive gear with the inner gear ring of the paddle wheel hub. The rotary encoder feeds the change of the pitch angle back to the controller, and then the closed loop PID negative feedback control of the motor.