被動式可變葉片裝置角機構之研製

Abstract

本研究設計一被動式可變葉片裝置角機構，令風力發電機能在額定轉速前先行葉片裝置角的調控，使系統之煞停機制啟動機率降低，藉此提升水平軸式風力發電機之發電效率。此被動式可變葉片裝置角機構主要將風力葉片於裝置滾珠軸承內，以此為中心連接至線性滑軌，並將一圓桿做為引導滾柱安裝在風力葉片上，使其接觸於前後具高低落差的引導軌道上，如此，當風力葉片受風開始轉動，便可利用轉動時產生的離心力使機構藉由線性滑軌保持順暢的平行移動，同時，引導滾柱受引導軌道的高低落差產生傾角，達到改變風力葉片裝置角的目的。本研究為匹配風力發電系統之煞停機制，因此設計在轉速到達110RPM時，機構能使葉片裝置角改變至10度，為了達到此目的且令機構更加穩定不晃動，另外加裝高強度之壓縮彈簧，使機構在低風速運轉時不隨意滑動，當裝置角改變使轉速下降後，再將機構推回、風力葉片恢復起始裝置角0度。本研究利用萬能材料試驗機進行設計的驗證，確認機構是否能正常運作並達到設計的運動狀態，經實驗驗證此機構可利用離心力達到改變葉片裝置角之目的。

In this thesis, a passive wind blade pitch control mechanism is designed to increase the power generation of horizontal-axis wind turbines. This mechanism is able to adjust the pitch angles of wind blades before rotor speed attains the rated rotor speed and the turbine activates the safety braking system. In the passive wind blade pitch control mechanism, the root of the wind blade is housed in the circular rail of a ball bearing which is connected to two linear guide rails. The centrifugal force generated by the rotating blade is able to make the blade move on the linear guide rails in the axial direction. A cylindrical rod passing through the wind blade root acts as a guiding roller which rests on a pair of linear guide rails with different heights. With the help of the height difference, the guiding roller is able to make the blade root tilt an angle which can thus change the pitch angle of the wind blade. To meet the restriction of the wind power safety braking system, the pitch control mechanism is designed to achieve a pitch angle of 10 degree when the rotor speed reaches 110RPM. A set of compression springs of high stiffness is used to stabilize the movement of the blade in the mechanism during operation. Moreover, the compression springs are also used to prevent the pitch angle of the blade from occurring when the turbine is operated at low wind speed and make the blade rotate from the maximum pitch angle back to it’s the original position when the wind speed decreases below the rated value. Finally, the pitch control mechanism was fabricated for experimental investigation. The material testing system (MTS) has been used to test the motion of the mechanism and the test results have validated the suitability of the design.