雙饋式風力發電機之運行與控制

Abstract

在本論文內，我們將針對電網電壓驟降對雙饋感應發電機（DFIG）的影響作分析，暫態下的過電流在沒有適當的控制或保護的系統中會損壞電力電子元件，因此，有必要在系統中使用保護裝置並研究其控制，現今發電機系統通常使用Crowbars來避免過電流通過轉換器，雖然此方法在電壓驟降下確實能有效運作，但如果電壓波動頻繁，那麼過多的開關切換將會導致功率追蹤效率的低落與控制的困難 因此本論文的目的乃是改良輕微三相電壓驟降下的控制架構，當故障發生時，使系統可以保持與電網連接，模擬乃利用Matlab / Simulink建立所需的模型，並使用感應發電機和機械風機的數學模型，並針對不同的轉子速度下（次同步和超同步）三相電壓驟降分別進行測試，以觀察在故障時系統的響應，並且在最後分析其結果

In this thesis, we analysised the impact of grid voltage sags on Doubly-Fed Induction Generator(DFIG). The over current in transient state will cause damage to power electronic devices without proper control or protection. Therefore, it is necessary to use the protection units and study the control. Nowadays, the generator system usually use the Crowbars to avoid over current pass through converters. Although it can properly work during voltage dips, but, if voltage fluctuations are frequent, excessive switching will cause control difficulties and ineffieicney in power tracking. The purpose of the thesis is to improve control scheme under lightly three phase voltage dip. System can keep connected to grid during fault occurred. Simulation was buid in Matlab/Simulink, using an induction generator and mechanical turbine math model. Different rotor speed(sub-synchronous and super-synchronous) are tested to observe system responses in three phase voltage faults, and the result are analysed at last.