The trial production process, put forward the future work direction of f. 1 Overview Due to the global energy crisis and environmental degradation, people have been seeking the use of clean renewable energy. As a clean renewable energy source, wind energy is becoming more and more competitive with the gradual maturity of its technology. The investment ratio of wind power is close to that of thermal power and hydropower. It is estimated that the R energy resources on the earth are about 200 trillion kWh. If you can use 1% of them, you can meet the human energy needs / Germany, Denmark, Netherlands, and the United States. The development and utilization of wind energy is at the forefront of the world. The wind energy resources that can be developed and utilized in China are extremely rich. In recent years, the annual installed capacity of new installed capacity is 100~200MW. Among them, Xinjiang and Inner Mongolia are the provinces with the largest installed capacity and fastest development of wind power. The rapid development of wind power has made the market demand for wind turbines increasingly strong. According to the needs of the market, Shanghai Electric Machinery Co., Ltd. organized the research and development of wind turbines and successfully developed the YFF series of wind turbines. Among them, the YFF355-6 6600/125kW4/6P690V generator has been put into mass production after successful trial operation. The design features of the 2 series wind turbines in the series design, fully consider the particularity of the operating conditions of the wind turbine operating environment, while taking into account high performance and reliability. To sum up, the series of generators have the following characteristics: “The wind turbines operate at outdoor high altitudes. Although the generators are installed in the machine bay, the environment is often harsh, so the protection requirements for the generators are high. The design protection level is IP54. Wind turbines are often operated in parallel with small power grids, which are susceptible to grid voltage and frequency fluctuations. The design overload capacity of generators is generally poor, to avoid the impact of generator voltage and frequency fluctuations. Stable operation With the wind power of the wind farm, the output power of the generator has also been changing. According to statistics, the wind turbine works below the rated power in 97% of the time. In order to improve economic efficiency, it is desirable that the generator also has high efficiency at light loads. This requires constant loss of the generator, that is, the sum of the iron loss and the mechanical consumption must be controlled at a low level. At the time of design, measures were taken to minimize the iron loss and the loss of the cooling fan. Taking a 600/125 kW wind turbine as an example, the sum of its iron consumption and mechanical consumption is lower than that of imported similar motors. The excitation of an asynchronous generator is provided by the reactive power of the grid. Too low a power factor of the generator will affect the field rate factor of the grid. Therefore, this series of wind turbines have a high power factor. In the case of both motor efficiency and motor temperature rise, the rated slip ratio of the generator is controlled at a higher value. During the operation of the wind turbine, its power has been fluctuating with the change of the wind, and the corresponding generator current also fluctuates. In order to reduce current fluctuations, buffer the impact on the system, and improve the life and reliability of the unit, the generator is often required to have softer characteristics. Under the same power fluctuation, the generator speed with large rated slip rate changes greatly, and the fan blade, gear box and generator rotor speed change will have an energy release or absorption process, and this part absorbs or releases the energy pair. The fluctuation of the generator power acts as a compensation. This greatly reduces the rate of current change between the generator and the grid, increasing the stability of the system. The greater the rated slip ratio of the generator, the softer its characteristics, and the greater the range of speed variation, the greater the compensation effect. The rated slip ratio of this series of asynchronous generators is about twice that of the general asynchronous motor. The wind turbine is installed in a high-altitude machine bay with a limited volume. This limits the size of the generator, which is designed as a surface-cooled compact motor with a greatly reduced volume. 3 Development of a series of wind turbines to solve several problems Although asynchronous generators and asynchronous motors are provided with excitation current by the grid, comparing the vector diagrams of the two can be seen as follows: the voltage of the asynchronous motor f / than its internal potential It is much bigger, and the f/s of the asynchronous generator is smaller. In the design of general asynchronous motor generators, if the induction potential calculation method of the motor is still used, the induced potential and the calculated magnetic flux density are both low, which may cause the magnetic flux to pass through during the actual operation of the generator. The angle a of the asynchronous motor / with the fifth is smaller, while the angle a of the asynchronous generator is larger. However, some of the calculation formulas in the asynchronous motor design program are derived based on the small angle a. If the design of the generator is applied to the design formula that only applies to the motor, it will cause a large error. To get more accurate results, these calculation formulas for asynchronous generators must use a slightly more complicated formula. If the angle between the stator voltage of the motor and the stator current is less than 901 and the angle of the generator is greater than 90%, the sign of some items in the motor design program must be changed, otherwise a large error will be caused. For asynchronous generators with a power of less than 1 kW, many users operate directly as generators using general-purpose asynchronous motors. However, this approach is not suitable for larger capacity wind turbines, especially for wind farms of a certain size. According to the vector diagram of the asynchronous generator, we have specially programmed a computer program for the electromagnetic design of the asynchronous generator to ensure the accuracy of the calculation. The accuracy of the calculation program is further verified by comparing the design values ​​of the generator parameters with the experimental values. Surface Cooling Asynchronous Motor Temperature Rise Calculation For a fully enclosed air-to-air cooling motor, there are generally two types of construction: one with a separate cooler and the other for the surface cooling method used by the generator series we developed. In contrast, the temperature rise calculation of a surface-cooled motor is particularly important. Because of the cooling method with the cooler, if the temperature rise of the generator is too high during the test, it can be improved by adjusting the cooling capacity of the cooler. For a surface-cooled motor, once the temperature rise of the motor is found to be too high, the room for improvement will be small. If the temperature rise calculation of the surface cooling motor is not performed, the motor design parameters cannot be accurately controlled, which will greatly increase the development risk. We have developed a temperature rise calculation program for surface-cooled motors, which has played an important role in the successful development of the wind turbine series. Wind turbines require high efficiency at light loads, which requires the fan losses of the motor to be as low as possible. To this end, we have worked with universities to develop low-loss cooling fans. On the basis of meeting the cooling requirements of the generator, the wind friction of the motor is reduced to a lower value. This has greatly improved the efficiency of the wind turbine and greatly reduced the noise of the motor. In the trial production process of wind turbines, the prototype machine base is rounded and welded, and the outer round welding has u-shaped cooling ribs for cooling air holes. The stator contains two independent 4-pole and 6-pole windings, Class F insulation. The stator windings are vacuum-pressured and solvent-free. The motor has two inner and outer air passages, the inner air passage passes through the stator and rotor air gaps and the axial air venting holes of the rotor, and the inner end of the coil and the inner air hole of the U-shaped cooling rib form a loop; the air volume of the outer air passage mainly flows through the U shape. The outer surface of the cooling rib. At the beginning of the trial production, the rotor was made of cast aluminum. In order to reduce the actual stray loss and iron consumption of the motor to further improve the efficiency of the motor and reduce the temperature rise of the motor, it was finally changed to a copper row structure. After the trial production was completed, the test analysis was carried out. In addition to the efficiency, other indicators of the generator were in line with the user's requirements. The test report shows that the motor's wind friction consumption is 7.2 kW. Excessive motor wind friction is the main factor affecting efficiency. To further improve the motor efficiency, the cooling fan must be optimized. We use the heating calculation program to analyze the influence of the air volume of the inner and outer wind passages on the temperature rise of the generator, determine the minimum air volume required by the motor, and calculate the wind resistance of the inner and outer wind paths of the generator. Preliminary wind pressure and air volume parameters of the inner and outer wind paths. The fan uses a highly efficient rear-tilt blade type, and the optimized goal is to control wind friction below 4.5 kW. The final test results show that the generator wind consumption is only 3.9 kW, and all the indicators of the generator meet the user requirements. After the successful prototype production, the test results of the generator were analyzed in detail, and the generator structure was further improved to meet the needs of batch production. When the prototype is prototyped, the generator base is made of steel plate welded structure. Because the use of cast iron stands, the cost of casting wood molds is very expensive, which is obviously a matter of consideration when there are many uncertain factors in the trial production stage. However, comparing the temperature rise calculation and test results of the generator, it can be found that the calculated temperature rise is 78K, and the actual sample temperature rises to 92.5K, which is quite different. The main reasons for the analysis are as follows: (a) The welding machine frame is easily deformed (especially in the case of a short cycle), which may cause the inner circle of the machine frame to have a certain roundness, which affects the cooperation between the outer circumference of the stator core and the base. Affects the heat dissipation of the motor; (b) The contact area between the heat dissipation rib and the machine wall directly affects the heat transfer capability. The ideal state is considered in the calculation, and it is difficult to ensure the connection of the heat dissipation ribs to the 100% area of ​​the machine frame during actual welding. The above two cases can be avoided by using a cast iron base. Considering that the use of cast iron stands during batch production can greatly shorten the cost and production cycle, and finally decide to maintain the design unchanged, the base is changed from welded structure to cast iron stand. After changing to a cast iron base, the calculated temperature rise is 67.6K. The test temperature rise is 68.5K, which is lower than the original 92.5K. The final test value of the 14K 600/125kW generator and the user's specified value and the original German motor parameters are as follows. 1: The user of the table requires the German company to import the motor on the power plant product efficiency power factor rated speed temperature rise. From the above comparison, it can be seen that the parameters of the generator have met the requirements, especially the efficiency and power factor values ​​have exceeded the specified value. Since the wind consumption of the motor is controlled at a low level through optimized design, the iron consumption of the generator is only 3.62 kW (about 6 kW for the same capacity motor), and the generator also obtains high efficiency at light load. The rate factor-load curve is shown in the following figure: It can be seen from the curve that the generator is particularly suitable for light load operation with light load operation. 5 The final design of the series of wind turbine design parameters (see Table 2) 6 future research directions mentioned earlier, in order to make the generator output power fluctuations less, the characteristics of the generator need to be relatively soft, which requires power generation The rated slip rate of the machine is much larger than that of a normal motor. For the squirrel cage asynchronous generator, to increase the slip rate, only the resistance of the rotor copper row can be increased, and the copper loss of the rotor is also increased, so that the total loss of the generator is greatly increased. Due to the limitation of rotor heating and stator winding temperature rise, the rated slip ratio of the generator must be controlled within a certain range. According to the information of domestic and foreign asynchronous generators, the rated slip ratio of squirrel-cage asynchronous generators above 250kW is basically no more than 2%. 11 Table 2YFF series wind turbine technical data model rated power (kW) rated Voltage (volts) stator current (A) rated speed (rev / min) efficiency power factor (cos command) maximum torque rated torque blocked torque rated torque blocked current rated current insulation level / temperature rise level weight (kg The winding type asynchronous generator is used, and the rotor circuit is connected in series with an external resistor, which solves the problem of heat generation inside the generator. The wound rotor asynchronous wind turbine produced by Vestas of Denmark adjusts the coaxial external rotor resistance of the string by electronic switching components, which can adjust the slip rate within 1% ~ 10%. This has greatly changed the performance of the generator set. Another advantage of this type of wind turbine is that the loss of the rotor circuit is mostly outside the motor, and the motor will not be overheated. The winding asynchronous wind turbine with doubly-fed speed regulation can also adjust the range of the generator. Expand to a larger scope. In addition, if there are low-speed generators without gearboxes, these newer types of wind turbines have already begun research in this area in China. Our next step will be to develop winding or other new wind turbines to better meet the needs of the market. : Department of Electrical and Computer Engineering, Jiaotong University. He has been engaged in the design of AC and DC motors for a long time. He is currently the deputy chief engineer of Shanghai Electric Machinery Factory and the director of the Technology Development Center.
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YFF series asynchronous wind turbine development