2011年1月19日星期三
Hidden troubles of wind turbine quality 1
With China’s sustained economic development, huge demand for electricity power has spurred the rapid development of the entire energy industry, and our vast wind resource reserves have provided sufficient space for the large -scale development of wind turbine power industry. Based on the incomplete statistics, our wind turbine power equipment output of the first half of 2009 has reached 4.27 million kW, representing an increase of 135.7%. However, wind power projects of 12.3 million kW have been approved to construct at the same time within the country, which may be followed by production capacity Surplus. As showed in" 2009 –2012 lnvestment AnaIysis and Prospects Forecast of China's Wind Power lndustry" issued by China Investment ConsuIting Co., Ltd.: there are currently over 70 wind power machine manufacturing enterprises in total in Our country, more 50 fan manufacturing enterprises, up to 100 tower manufacturlnq enterprises, and about 30 flange manufacturing enterprises As calculated by enterpr1se production capacity, it has been far more than market capacity and wind turbine market has been transformed from seller’s market to buyer's market. Fierce vicious competition has been carried Out among manufactures in order to obtain orders, which brought considerabIe risks and hidden troubles for product quality.
2011年1月12日星期三
How does the wind turbine produce electricity?
1.The wind passes over the blades creating lift (just like an aircraft wing) which causes the rotor to turn.
2. The blades turn a low-speed shaft inside the nacelle: wind energy is converted into rotating, mechanical energy.
3. In most wind turbines, mechanical energy is channelled to a gearbox. The gears connect the low speed shaft of the rotor with a high speed shaft that drives the generator. Here the slow rotation speed of the blades is increased to the high speed of generator revolution (ratio: 1:100). Some wind turbines do not contain a gearbox and instead use a direct drive mechanism to produce power from the generator.
4. The rapidly spinning shaft drives the generator to produce electric energy.
5. Electricity from the generator (around 700 V) goes to a transformer which converts it to the right voltage for the distribution system (33,000 V).
6. The electricity is transmitted via the electricity network. The nacelle is rotated automatically to follow the changing direction of the wind so as much energy as possible is captured.
Wind turbines generate energy at wind speeds of 4-25 metres per second. When turbines are generating electricity, the rotor speed will be 9-19 revolutions per minute, depending on the wind speed and the turbine type. If the wind reaches speeds over 25 metres per second, which happens rarely, the wind turbine stops because such speeds place too much strain on the turbine’s components. In the early days of modern wind power, wind turbine rotors were 20 metres in diameter and had a capacity of 20-60 kW. Ten years later, the machines had a capacity of 500 kW, and today offshore turbines can reach up to 5 MW or more, spanning 120 metres – longer than a football field. The average size of onshore turbines being manufactured today is around 2.5-3 MW. One 2.5 MW onshore turbine produces power for over 1,500 EU households.The larger blade lengths capture more wind and therefore produce more electricity and reduce the cost of power generation.
2. The blades turn a low-speed shaft inside the nacelle: wind energy is converted into rotating, mechanical energy.
3. In most wind turbines, mechanical energy is channelled to a gearbox. The gears connect the low speed shaft of the rotor with a high speed shaft that drives the generator. Here the slow rotation speed of the blades is increased to the high speed of generator revolution (ratio: 1:100). Some wind turbines do not contain a gearbox and instead use a direct drive mechanism to produce power from the generator.
4. The rapidly spinning shaft drives the generator to produce electric energy.
5. Electricity from the generator (around 700 V) goes to a transformer which converts it to the right voltage for the distribution system (33,000 V).
6. The electricity is transmitted via the electricity network. The nacelle is rotated automatically to follow the changing direction of the wind so as much energy as possible is captured.
Wind turbines generate energy at wind speeds of 4-25 metres per second. When turbines are generating electricity, the rotor speed will be 9-19 revolutions per minute, depending on the wind speed and the turbine type. If the wind reaches speeds over 25 metres per second, which happens rarely, the wind turbine stops because such speeds place too much strain on the turbine’s components. In the early days of modern wind power, wind turbine rotors were 20 metres in diameter and had a capacity of 20-60 kW. Ten years later, the machines had a capacity of 500 kW, and today offshore turbines can reach up to 5 MW or more, spanning 120 metres – longer than a football field. The average size of onshore turbines being manufactured today is around 2.5-3 MW. One 2.5 MW onshore turbine produces power for over 1,500 EU households.The larger blade lengths capture more wind and therefore produce more electricity and reduce the cost of power generation.
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