永磁同步發電機之預測直接扭力控制與風力發電機之獨立葉片控制

Predictive Direct Torque Control of the PMSG and Individual Pitch Control of Wind Turbine

楊適宇(Shih-Yu Yang)

指導教授 ： 林輝政

國立臺灣大學/工學院/工程科學及海洋工程學研究所/博士(2016年)

https://doi.org/10.6342/NTU201610312

摘要

本論文推導出預測直接扭力控制法，主要應用於永磁同步發電機。普遍而言，永磁同步發電機的控制需要很高的取樣頻率以給予轉換器開關指令，然而若是用本論文推展出來的預測扭力控制，得以在取樣的當下計算出三個最佳的開關切換時間與合適的開關切換組合。與傳統的永磁同步機控制方法相比，利用此控制方法能有效減少永磁同步發電機的電機扭力漣波與定子磁通量的振幅，因此，使用本論文所提出的預測直接扭力控制法，可以有效降低取樣頻率。在永磁同步機系統中，背對背轉換器中間的電容需要維持固定電壓，此電壓能提供發電機側的轉換器順利運作，故本論文亦利用電網電壓方位向量控制法來穩定電容的電壓，該方法可決定電網側轉換器的開關切換，此外，該控制方法還可決定由電容流向電網實功與虛功。另一方面，葉片控制在現代風力發電機中是相當重要的議題，葉片控制的目的在於當風速過大時，要將風機轉速維持在額定轉速。由於風力發電機運行時，葉片會因位置不同受到風速與重力的影響，而承受到週期性負載，如此一來容易造成葉片的疲勞與損壞。本研究的葉片控制技術包含固定轉速與消除葉片的彎曲力矩振盪兩方面的結合：使用擾動建議控制法來調整風機轉速，再透過d-q 軸轉換，將葉片的彎曲力矩在d-q 座標中進行分析，由此發展出獨立葉片控制。

關鍵字

電網電壓方位向量控制 ； 獨立葉片控制 ； 永磁同步發電機 ； 預測直接扭力控制 ； 風力發電機

並列摘要

This thesis concerns the application of the predictive direct torque control (PDTC) method to a permanent magnet synchronous generator (PMSG). In classical methods for controlling a PMSG, the sampling frequency of the controller must be precisely determined. However, the use of PDTC in this study enables three optimal duty cycles to be predicted at the moment of sampling, significantly reducing the ripple of the electromagnetic torque and the amplitude of the stator flux below those caused by conventional control methods. Therefore, the new method allows a lower sampling frequency than the traditional method. To operate the machine side converter, the DC bus capacitor voltage must be maintained within an acceptable and stable range. Grid voltage oriented vector control was used to control the active power and the reactive power, which are delivered from the DC bus capacitor, as well as to control the voltage. On the other hand, for the modern wind turbine, the pitch control is an every important issue. The purpose of the pitch control is to maintain the rotor speed at the rated speed when the wind speed is above rated wind speed. The wind turbine’s blades are exerted the periodic loads from the wind and gravity, which may easy to let the wind turbine’s blade fatigue. The pitch control method that includes the speed regulation and reduction of bending moment’s oscillation is introduced in this thesis. The disturbance accommodating control handles the speed regulation problem. Moreover, by analysis the bending moment of the blade under the d-q transformation, the individual pitch control reduces the oscillation of bending moment.

並列關鍵字

Grid voltage oriented vector control ； individual pitch control ； permanent magnet synchronous generator ； predictive direct torque control ； wind turbine

參考文獻

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