Wind energy is a rich, clean and renewable primary energy, to achieve reliable, efficient and economical "wind energy - mechanical energy - energy" transformation and transportation is an important issue in the current study. In view of the problem of wind power generation control, the status quo of related technology research at home and abroad is reviewed. The structure and principle of 1.5 MW direct drive permanent magnet wind turbine are analyzed, and the grid connection technology of generator set is expounded.
First, the wind power profile
Wind energy, like solar energy, is a kind of renewable resource, which is clean, rich and disposable. It has become a kind of energy which has been paid much attention in the process of social and economic development. The amount of wind energy is very large, the total amount of wind resources in the world is about 2.74 × 109 MW, the vast majority of these can be used by us, more than 10 times the water resources can be exploited There are three major wind power markets in the world, they are the United States, Germany, Spain, and China has a large reserves of wind energy, because China's vast land area, so the distribution of these energy is very broad, coupled with China's wind power in recent years The rapid development of industrial technology, China will become the world's fourth largest wind power market. In the present China, the wind power industry will have a very broad, full of vitality of the development prospects, and will be in a state of rapid development. Now the wind power installed in the country and the scale of the continuous realization of the wind power costs have been reduced, so the wind power industry will become the dream of some people to achieve the dream of investment goals.
The Xinjiang Uygur Autonomous Region in the western region accounts for 15% of the total land area, which can generate abundant power resources because of its unique geological conditions. In Xinjiang, the total area of the wind area that can be exploited and developed is more than 140,000 square kilometers, mainly distributed in Dabancheng, Lop Nur, Tacheng and the small steam and other places, these winds can be installed in the total amount of more than 7900 million The Xinjiang by virtue of the rich wind energy resources formed on domestic and foreign wind power enterprises have a strong attraction of the wind power market. The relevant departments to do a preliminary plan to achieve the total installed capacity of wind power in 2020 more than 10 million kilowatts of breakthroughs, to Xinjiang wind power can be large-scale outward delivery of the target.
Second, the composition and classification of wind turbine
Wind turbines are units that convert wind energy into electrical energy, consisting mainly of wind wheels, nacelles, towers, and the overall base base. The wind wheel part includes the blade and the hub, its working principle is that the blade itself becomes aerodynamic external form, when subjected to the impact of the air when it can form a certain force so that the wind wheel force began to turn, and finally the hub The torque is transmitted to the main drive system. The cabin part includes the chassis, the fairing and the cabin cover, and the other key components except the main control panel are mounted on the chassis. Through the role of the tower, the cabin can be raised to a pre-set position, the tower above there are other important parts, including the connection between the motor and the master line and personnel up and down the ladder and so on. The base is mainly built from the accumulation of reinforced concrete, it can the entire wind turbine set firmly on the ground, but also to take lightning and grounding device.
According to the different unit characteristics and application purpose, the main types of wind turbine and its control system are summarized as follows: According to the capacity, we can divide the generator into three types: the capacity is less than 10 kilowatts is a small generator; Capacity of more than 9 kilowatts, 99 kilowatts or less is the medium-sized generating units; capacity of more than 99 kilowatts is a large-scale generating units. The relationship between the spindle and the horizontal ground as a standard can be divided into horizontal and vertical axis of the two types of units. In the two sets of generators, the former is a successful group of generators, and the advantage is that the wind wheels can be placed high to avoid the effects of surface conditions on wind turbine operation. Horizontal axis The main components of the generator, such as generators, steering devices and spindles, are in the cabin of the generator.
The wind turbine is divided into the following categories: single blade wind turbine, double blade wind turbine, three blade wind turbine and multi-blade wind turbine. According to the location of the unit wind wheel can be divided into: upwind wind turbine, downwind wind turbine. According to the type of unit drive chain can be divided into: direct drive wind turbine, double-fed variable speed constant frequency wind turbine and hybrid wind turbine. Direct drive permanent magnet synchronous generator connected directly with the wind turbine, its speed is low, the number of poles, set, the rotor size, was flat structure, with a large inertia characteristics, is conducive to stabilize the wind instability caused by the potential Jump up and down. Direct-drive wind turbines are gearless gear variable pitch category, the wind wheel shaft does not connect with each other through other components and low-speed generators, direct-drive wind turbine to use full power converter. In the case of double-fed variable-speed constant-frequency type wind turbines, the pitch angle of the wind turbine blades is not fixed and can be adjusted according to the actual requirements, and this type of wind The generators are equipped with a doubly-fed generator, which is capable of speed regulation, while the transmitted electrical energy is also a constant frequency constant voltage. Hybrid wind turbines, hybrid wind turbines using single-stage gearbox and medium-speed generators, is a direct-drive wind turbine and conventional wind turbine generator mix. Although there are many types of wind power generating units, but now dominate the "three blades, horizontal axis, the wind direction, pitch, variable speed, constant frequency wind turbine."
Third, 1.5 MW direct drive permanent magnet wind turbine structure
The main components of the 1.5 MW unit include: blade, hub, pitch system, generator rotor, generator stator, yaw system, wind measurement system, lubrication system, base, tower, electronic control system and cooling system.
The entire blade within the wind turbine is the most important part of the wind energy absorption, which is equipped with a powerful lightning protection device. Through the pitch bearing to achieve the connection with the hub.
The main function of the hub is to firmly connect the various leaves together, at the same time bear all the load carried by the blade load, and then further transmitted to the generator shaft part. The hub is made up of three radially flared doors.
The generator is able to further convert the mechanical kinetic energy generated by the rotation of the impeller into electrical energy. The motor is equipped with multi-pole permanent magnet synchronous class, this motor has a simple structure, reliable operation, high efficiency, small size, etc., permanent magnet synchronous generator rated power of 1580 kW, rated speed 20.5rpm, speed The range is 9rpm ~ 17.3rpm, the number of poles is 88, the rated voltage is 690V.
The automatic yaw system automatically determines the direction of the wind turbine based on the signal provided by the weather vane. When the wind direction deflection, the control system according to the wind vane detection signal, control yaw drive device so that the yard yang the wind. The yaw system is damped at work and is optimized for yaw rotation in accordance with the optimized yaw rate. There are control cabinets, hoists, yaw systems, heat exchange systems, etc., there are wind outside the system, the cabin of the base of the impeller and the generator can be static and dynamic load to the tower.
The wind speed meter and the weather vane sensor are installed at the rear of the cabin. The wind direction signal reflects the deviation between the fan and the main wind direction. When the wind direction changes continuously, the controller controls the three yaw drives according to the wind vane signal. Main wind direction.
Brake system, which is equipped with three sets of independent blade blade pitch system, even if one of the pitch system problems can not feather, the other two leaves can also be independent of the pitch air brake to ensure that The unit can normally stop running. The hydraulic brake is carried inside the motor, and its key function is to maintain the unit at the set stop. The electrical control system has three functions: normal operation control, operation condition monitoring and safety protection.
Four, direct drive permanent magnet wind turbine variable speed constant frequency and network operation
With the development of power electronics technology, electric energy conversion device has been widely used in wind power generation and played an important role. In order to improve the efficiency of wind energy utilization, must achieve variable speed operation, that is, to achieve variable speed constant frequency wind power generation system. The use of permanent magnet synchronous generator as a wind turbine, the AC power into DC, and then the appropriate control of the inverter will be converted into constant frequency, constant voltage AC, and then by the step-up transformer access to the grid, to achieve grid And gradually change the inverter modulation signal so that the inverter output voltage phase ahead, so as to gradually increase the wind turbine to the power transmission network.
As the power electronic converter device can achieve voltage and frequency conversion, therefore, in the case of variable speed operation of the generator, regardless of the power of its issued by what kind of voltage and frequency, can be used to transform the converter device, and then network, The variable speed operation, the use of high efficiency wind energy, and after the converter device and network, making the electromechanical system decoupling, there is no synchronous motor power angle stability problem, the converter device also has a certain reactive power control capability, improved wind Power generation voltage problem. One of the important advantages of variable speed constant frequency wind power generation systems is that the wind turbine can operate in the best condition in the windy area.
Direct drive permanent magnet generator in the variable speed constant frequency grid running process does not occur in the current impact, making the power generation system can be normal operation, the reason is because the use of frequency conversion device to regulate the output of the current. Because the synchronous generator and the power grid in the operation does not exist in the working flat on the link, so the wind wheel and the generator can run at different times when the speed, while avoiding the grid in the operation of any mistakes. It is possible to control the load capacity of the output power by using the impedance matching and the power tracking in the wind power operation system. This ensures that the wind turbine can continue to operate in the best condition and transport the maximum amount of electricity to the grid The
Fifth, the development direction of wind power control technology
Now the development of science and technology to promote the field of wind power to enhance the level of rapid upgrading of wind power facilities and equipment, from the current situation, the main direction of development of wind power is reflected in the transmission technology from the structural design to the compact, flexible , The development of light and other aspects of the geographical area from the land gradually turned to the sea, due to the vast territory of China's territorial waters, the extension of the coastline is considerable, can be applied in the field of wind power resources sufficient, so the offshore wind farm will be the future of China's wind power important Development project. Large-scale, high concentration of long-distance large-scale development of wind power costs continue to decline, gradually close to conventional energy. Application of energy storage system in wind power grid connection and optimization of wind power economy with energy storage system. Wind power base of the wind farm interconnection - multi-terminal DC system, can achieve independent active and reactive power control, better control, through the multi-terminal DC system interconnection, can increase the reliability of wind farm power transmission and flexibility. It has important theoretical and practical value to improve the reliability of large-scale wind farm and the flexibility of transmission and improve the quality of AC power.
This paper summarizes the current situation and development prospects of wind energy at home and abroad, the composition of wind turbine system and the characteristics of various generating units. Combined with the localization process of large wind turbine in China, the structure and function of 1.5 MW direct drive permanent magnet wind turbine are analyzed. Finally, the grid connection technology of wind turbine is expounded. And prospects for the future development of wind power control technology several trends.
Article from NdFeB Industry Network