能源科學導論4-(編輯修改稿)
2025-08-28 15:20 本頁面
【文章內(nèi)容簡介】 The high speed shaft rotates with approximately. 1,500 revolutions per minute (RPM) and drives the electrical generator. It is equipped with an emergency mechanical disc brake. The mechanical brake is used in case of failure of the aerodynamic brake, or when the turbine is being serviced. The gearbox has the low speed shaft to the left. It makes the high speed shaft to the right turn approximately 50 times faster than the low speed shaft. The yaw mechanism uses electrical motors to turn the nacelle with the rotor against the wind. The yaw mechanism is operated by the electronic controller which senses the wind direction using the wind vane. The picture shows the turbine yawing. Normally, the turbine will yaw only a few degrees at a time, when the wind changes its direction. The electrical generator is usually a socalled induction generator or asynchronous generator. On a modern wind turbine the maximum electric power is usually between 600 and 3000 kilowatts (kW). The electronic controller contains a puter which continuously monitors the condition of the wind turbine and controls the yaw mechanism. In case of any malfunction, (. overheating of the gearbox or the generator), it automatically stops the wind turbine and calls the turbine operator39。s puter via a telephone modem link. The hydraulics system is used to reset the aerodynamic brakes of the wind turbine. The cooling unit contains an electric fan which is used to cool the electrical generator. In addition, it contains an oil cooling unit which is used to cool the oil in the gearbox. Some turbines have watercooled generators. The anemometer and the wind wane are used to measure the speed and the direction of the wind. The electronic signals from the anemometer are used by the wind turbine39。s electronic controller to start the wind turbine when the wind speed reaches approximately 5 metres per second (10 knots). The puters stops the wind turbine automatically if the wind speed exceeds 25 metres per second (50 knots) in order to protect the turbine and its surroundings. The wind vane signals are used by the wind turbine39。s electronic controller to turn the wind turbine against the wind, using the yaw mechanism. 2).What makes the rotor turn? The reason why an aeroplane can fly is that the air sliding along the upper surface of the wing will move faster than on the lower surface. This means that the pressure will be lowest on the upper surface. This creates the lift, . the force pulling upwards that enables the plane to fly. ? 3).Adding Wind Speeds and Directions (Wind Velocities) ? The wind which hits the rotor bla
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