風力-感應發電機系統之電壓及頻率調整器設計

本論文之主要目的在研究風力-感應發電機系統之電壓調整器及頻率調整器。研究的方向著重於風力發電系統中的靜態同步補償器及葉片旋角的控制策略探討與控制器設計。在以靜態同步補償器及葉片旋角調整感應發電機端電壓及機械功率時，本文除採用輸出迴授型線性二次式控制理論來進行控制器之設計外，亦以極點指定的方法來重新修正線性二次式之加權矩陣，以改善閉迴路系統的阻尼特性。此外，本論文亦提出一個雙座標軸轉換方法，將原來在耦合平面上的靜態同步補償器電流轉換至解耦合平面，以獲得靜態同步補償器實功及虛功的解耦合控制。再者，為了解決輸出迴授控制器穩態誤差的問題，本文將發電機匯流排電壓的偏移量及靜態同步補償器直流電壓的偏移量分別予以積分，並當作新的狀態變數。在頻率控制方面，本論文由獨立運轉的感應發電機穩態分析結果得到一個重要的結論：在固定發電機端電壓時，發電機的定子頻率與轉速成正比。此結論將有助於使用調速機來精確控制發電機的輸出頻率。在本論文中，另外一個頻率控制策略採用發電機端電壓之相對相位角的變化率來觀察發電機輸出頻率的偏移量，進而達到頻率控制之目的。為了進一步證明所提方法的有效性，除了以電腦模擬分析外，並以實體製作所獲得的實驗結果與模擬結果進行比較。在不同的干擾方式下，由系統的動態響應結果發現本文所提出的電壓及頻率調整器確實可以有效控制感應發電機之端電壓及頻率。

關鍵字

葉片旋角；頻率調整器；感應發電機；靜態同步補償器；電壓調整器；風力發電系統

並列摘要

Voltage regulator and frequency regulator are designed for a wind turbine-induction generator system. Much effort has been placed on control strategy exploration and controller design of the static synchronous compensator (STATCOM) and the variable blade pitch in a wind energy conversion system (WECS). An output feedback linear quadratic controller is designed for the STATCOM and the variable blade pitch in order to reach the voltage and mechanical power control. Then a systematic approach based on pole assignment technique is used to refine the weighting matrix for the linear quadratic controller such that satisfactory damping characteristic can be achieved for the closed-loop system. To attain the decoupled real and reactive power control loops for the output feedback controller, a two-reference-frame transformation is proposed to convert the STATCOM currents from the coupled d-q plane to another decoupled d-q plane. In addition, to ensure zero steady-state voltage errors for the output feedback controller, the integrals of generator bus voltage deviation and DC capacitor voltage deviation are employed as the additional state variables. An important conclusion obtained from steady-state analysis results for an isolated induction generator is that the stator frequency is proportional to the rotating speed at constant stator voltage. The advantage is that, through the action of the speed governor, the stator frequency can be regulated precisely. Besides, in another frequency control strategy, the relative rotating speed measured by the rate of change of voltage phase angle at generator terminal, is used to estimate stator frequency. To demonstrate the effectiveness of the proposed approaches, both time domain simulations and experiments are conducted. Dynamic response curves for the system subjected to various disturbances are presented. It is found that the proposed approaches can provide effective voltage and frequency control for induction generators.

並列關鍵字

Blade pitch angle ； frequency regulator ； induction generator ； static synchronous compensator (STATCOM) ； voltage regulator ； wind energy conversion system (WECS).

參考文獻

[2] 台灣經濟研究院，「台灣地區應用分散型電力可行性研究期中報告」， 2002年7月。

[4] G.L. Johnson, Wind Energy System, NJ, Prentice Hall International, 1985.

[5] Åke Larsson, “Flicker emission of wind turbines during continuous operation,” IEEE Trans. on Energy Conversion, vol. 17, no. 1, pp. 114-118, 2002.

[6] Åke Larsson, “Flicker emission of wind turbines caused by switching operations,” IEEE Trans. on Energy Conversion, vol. 17, no. 1, pp. 119-123, 2002.

[7] T. Thiringer, T. Petru and C. Liljegren, “Power quality impact of a sea located hybrid wind park,” IEEE Trans. on Energy Conversion, vol. 16, no. 2, pp. 123-127, 2001.

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風力-感應發電機系統之電壓及頻率調整器設計

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