字幕列表 影片播放 列印所有字幕 列印翻譯字幕 列印英文字幕 Windmills have been assisting mankind to convert the energy contained in wind to 過去兩千年來 風車一直在幫助人類將風中所含的能量 轉化成許多其他有用的形式 many other useful forms for the last two thousand years. 今天的風力發電機能夠將大量的風能轉化成電力 Today's wind turbines are capable of converting a great amount of energy in 歸功於使用最先進的空氣動力學分析 和其他性能提升設備所開發出的葉片 the wind into electricity. 在這部影片中，我們將以簡單而科學的方式 探索這些不同的技術 This is due to the blades which are developed using state-of-the-art 首先讓我們進入最基本的運作 aerodynamic analysis and the other performance-enhancing equipment. 如果吹拂的風可以轉動機翼 我們將從附著在其上的發電機接收電力。 In this video we will explore these different set of technology in a simple 然而吹拂的風是如何轉動機翼的? yet scientific way. 讓我們仔細地看葉片 First, let's get into its basic working 葉片從底部到尖端 由許多不同尺寸和形狀的橫截面所組成 If the blowing wind can turn the wing, we will receive electricity from the 簡易的機翼技術使得風力渦輪機葉片轉動 generator that is attached to it. 這意味著當流體在葉片上移動時產生上升力。 However, how does the blowing wind turn the wing ? 這樣子風機實現了我們常看到的基本旋轉。 Let's have a close look at the blade. 正如你在一列移動火車所上體驗到的東西 移動中的風機也相對地體驗到風 The Blade has a lot of airfoil cross-sections consisting of different 對於移動中的葉片 相對的風速如圖所示 sizes and shapes from the root to tip. 因此風力渦輪機葉片以傾斜的方式定位 以便與相對風速對準 The simple airfoil technology makes the wind turbine blade turn. 當葉片速度增加到尖端時 相對風速朝向尖端變得更傾斜 That means that a lift force is produced when a fluid moves 這表示葉片從根部到尖端都是連續的扭轉。 over an airfoil. 然而這種旋轉不能直連結到發電機。 This way the wind turbine achieves the basic rotation 因為由於噪音以及機械強度的問題 風力渦輪機葉片通常以非常低的轉速轉動 we are accustomed to seeing. 考慮到這種低速旋轉 不能從發電機中產生任何有意義的電力頻率。 Just as in a moving train 因此在連接發電機之前 速度會在齒輪箱中增加 you experience things relatively, the moving wind turbine blade also 齒輪箱採用行星齒輪組裝置來實現高轉速比。 experiences the wind relatively. 制動器也裝在機艙中 For the moving blade the relative wind velocity is 制動器的功能是在風過大的條件下阻止葉片旋轉 as shown. 因此通過電纜的電力 將朝向升壓變壓器所在的基座。 Therefore the wind turbine blade is positioned in a tilted manner 為了進行最大功率提取 風力發電機正常應該面向風力 in order to align with the relative wind speed. 但是風的方向會隨時改變 As the blade velocity increases to the tip the relative wind speed becomes more 在機艙頂部的速度傳感器 會測量風速和風向 inclined towards the tip. 風向的偏差被發送到電子控制器 This means that a continuous twist is given to the blade from the root to tip. 電子控制器又向偏航機構發送適當的信號以校正誤差 However this rotation cannot be directly coupled to a generator. 可以看到偏航馬達如何轉動機艙 Because the wind turbine blades typically turn at a very low rate of rpm 因此風力渦輪機將始終與風向對齊 due to the issues of the noise and mechanical strength. 根據風速 風的相對速度角也會發生變化。 Considering this low-speed rotation we cannot produce 葉片傾斜機構使葉片傾斜 並確保葉片與相對速度有適當對準 any meaningful electricity frequency from a generator. 因此葉片總是處於與相對風流向是最佳角度。 So before connecting to the generator the speed is increased in a gearbox. 風力發電機的效率是非常有趣的主題 The gearbox uses a planetary gear set arrangement 為了更好地了解風力發電機的效率 to achieve the high speed ratio. 假設你正在測量風力發電機 順風和逆風的風速 A break also sits in the nacelle. 可以注意到 逆風的風速遠遠小於順風的風速。 The function of the brake is to arrest wind blade rotation 這是因為葉片從風中吸收了一些動能 during excessively windy conditions 同大小的能量被轉換為風力渦輪機的機械能 Consequently the electricity that is 有趣的是 風力渦輪機吸收了100％的可用動能 passed through the cables towards the base 只有當逆風的風速變為零時 where a step-up transformer is situated. 然而逆風的零風速 在物理上是不可能的 The wind turbine should face the wind 這個卡通動畫清楚地描繪了這一事實 normally for maximum power extraction. 零逆風速度簡單來說 整個流體是卡住的 But the wind direction can change at any time. 實際物理上的流體需要一定的出風速度 A velocity sensor 這也就意味著 有一個理論最大效率可以被達到 on the top of the nacelle measures the wind speed and direction. 此極限又稱為貝茲極限 The deviation in the wind's direction 基本上這表示世界上沒有風力發電機 可以超過59.3％的效率限制 is sent to an electronic controller which in turn sends an appropriate signal to the 希望你現在對風力發電機的操作 有了很棒的看法 yawing mechanism to correct the error. 謝謝收看 You can see how the yaw motors turn the nacelle. Thus the wind turbine will always be aligned with the wind direction: According to the wind speed the relative velocity anggle of the wind also changes. A blade tilting mechanism tilts the blades and guarantees a proper alignment of the blade with the relative velocity. Thus the blades are always at the optimum angle of attack with the relative wind flow. Efficiency of the wind turbine is the really interesting topic. To gain a good insight into wind turbine efficiency assume that you are measuring wind speed at upstream and downstream over wind turbine. You can note that the wind speed at the downstream is much smaller than the upstream. This is because the blades absorb some kinetic energy from the wind. The same amount of energy is converted as mechanical power of the wind turbine. It is interesting to note that a wind turbine absorbs 100 percent of the available kinetic energy only if the downstream wind speech becomes zero. However zero wind speed at downstream is a physically impossible condition. This cartoon animation clearly depicts this fact. Zero downstream speed simply means the whole flow is stock. This physical reality of the flow demands a certain amount of exit wind speed. That means that there is a theoretically maximum efficiency a wind turbine can achieve. This limit is known as Betz's limit. Essentially it means that no wind turbine in the world can ever cross the efficiency limit of 59.3 percent. We hope you have now developed a good inside of the operation a wind turbines. Thank You !