At present, the bottleneck restricting the development of offshore wind energy worldwide remains offshore wind turbines. High reliability and ease of maintenance are the most important properties of offshore wind turbines. Wind turbines with gearboxes of 5 MW and above will be the next development direction of mainstream models.
The global market share of wind turbines with gearboxes is more than 80%. Most of the wind turbine manufacturers in the world, such as Vestas, GE Wind, Siemens, REpower, Sinovel Wind Power Company, etc., all use this technology
The drive method direct without gearbox is divided There are two forms: excitation direct drive and permanent magnet direct drive. The German company Enercon, which uses direct drive and excitation gearboxless systems, has a market share of around 10% sur international market and its single machine capacity has reached 6MW. However, no units have yet been put into the sea.
In order to withstand the strong wind load, seawater corrosion and wave impact at sea, the foundation of offshore wind turbines is much more complex, technically difficult and expensive. to build only terrestrial structures. The selection of foundations should comprehensively consider the influence of various factors, mainly water depth, seabed condition, load, construction difficulty and construction cost. At present, single pile steel structure foundations and concrete gravity foundations are mainly used in Europe. China's first demonstration offshore wind farm adopts the world's unique multi-pile concrete cover structure, which is a major innovation in wind power foundation design offshore.
The concept of semi-direct drive arose from problems encountered in the development of direct-drive, dual-fed wind turbinesas part of a process of large-scale development. .characteristics of both.
The difference between a semi-direct drive wind turbine and a direct drive wind turbine:
1. The principles of the two are different,
1. A direct drive wind turbine is a generator directly driven by the wind, also known as a gearless wind turbine. This generator is driven by a multi-pole motor directly connected to the turbine, eliminating the need for a traditional component such as a multi-pole motor. gearbox.
2. The semi-direct drive wind turbine adopts single-stage or double-stage speed-increasing gearbox, multi-pole synchronous generator and full-capacity converter. Furthermore, in order to reduire the weight of the engine room, semi-direct drive wind turbines are mostly compact designs, that is, the low-speed shaft is eliminated or the low-speed shaft length is eliminated. speed is reduced and power output is reduced. The shaft of the speed increase box is directly connected to the main shaft of the generator.
2. The advantages of both are different
1. The direct drive wind turbine has no gearbox, which reduces transmission losses and improves power generation efficiency, especially in low conditions. wind speed environments, the effect is more significant.
2. The semi-direct drive generator rotates at high speed. This characteristic determines that the semi-direct drive can on the one hand improve the reliability and service life of the gearbox, at the same time as the direct drive generators, it can take etake into account the corresponding design of the generator and improve the design and manufacturing conditions. of high power direct drive generators.
3. The structures of the two are different
1. The direct drive wind turbine uses a multi-pole motor and a turbine to connect directly to the drive, eliminating the problem. needThe gearbox is a traditional component. Since the gearbox is a component that is easily overloaded and has a high rate of premature damage in megawatt wind turbines, there is no direct drive wind turbine without a gearbox.
2. The concept of semi-direct drive arose from the problems encountered in the development of large-scale direct-drive and dual-fed wind turbines, taking into account the characteristics of both. Structurally speaking, semi-direct drive is similar to double-a drivepower supply and has the characteristics of various configuration forms. At the same time, the pinless structure under current research also has a similar appearance to the direct drive.
The above content refers to Baidu Encyclopedia - Semi-direct drive wind turbine
The above content refers to Baidu Encyclopedia - Direct drive wind turbine